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Diffstat (limited to 'meta-agl-drm-lease/recipes-core/psplash/files/0011-Import-drm-howto-modeset.c-as-psplash-drm.c.patch')
| -rw-r--r-- | meta-agl-drm-lease/recipes-core/psplash/files/0011-Import-drm-howto-modeset.c-as-psplash-drm.c.patch | 764 |
1 files changed, 764 insertions, 0 deletions
diff --git a/meta-agl-drm-lease/recipes-core/psplash/files/0011-Import-drm-howto-modeset.c-as-psplash-drm.c.patch b/meta-agl-drm-lease/recipes-core/psplash/files/0011-Import-drm-howto-modeset.c-as-psplash-drm.c.patch new file mode 100644 index 00000000..767dbf4b --- /dev/null +++ b/meta-agl-drm-lease/recipes-core/psplash/files/0011-Import-drm-howto-modeset.c-as-psplash-drm.c.patch @@ -0,0 +1,764 @@ +From d5a9fb5cd8505c16d4d75c695af1e64597d36c86 Mon Sep 17 00:00:00 2001 +From: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com> +Date: Mon, 25 Apr 2022 10:59:50 +0300 +Subject: [PATCH 11/17] Import drm-howto modeset.c as psplash-drm.c + +Imported as is from +repo: https://github.com/dvdhrm/docs.git +branch: master +commit: fc5c63f +path: drm-howto/modeset.c + +drm-backend backport from: +https://patchwork.yoctoproject.org/project/yocto/cover/20220425075954.10427-1-vasyl.vavrychuk@opensynergy.com/ + +Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com> +--- + psplash-drm.c | 735 ++++++++++++++++++++++++++++++++++++++++++++++++++ + 1 file changed, 735 insertions(+) + create mode 100644 psplash-drm.c + +diff --git a/psplash-drm.c b/psplash-drm.c +new file mode 100644 +index 0000000..c9a9f5c +--- /dev/null ++++ b/psplash-drm.c +@@ -0,0 +1,735 @@ ++/* ++ * modeset - DRM Modesetting Example ++ * ++ * Written 2012 by David Rheinsberg <david.rheinsberg@gmail.com> ++ * Dedicated to the Public Domain. ++ */ ++ ++/* ++ * DRM Modesetting Howto ++ * This document describes the DRM modesetting API. Before we can use the DRM ++ * API, we have to include xf86drm.h and xf86drmMode.h. Both are provided by ++ * libdrm which every major distribution ships by default. It has no other ++ * dependencies and is pretty small. ++ * ++ * Please ignore all forward-declarations of functions which are used later. I ++ * reordered the functions so you can read this document from top to bottom. If ++ * you reimplement it, you would probably reorder the functions to avoid all the ++ * nasty forward declarations. ++ * ++ * For easier reading, we ignore all memory-allocation errors of malloc() and ++ * friends here. However, we try to correctly handle all other kinds of errors ++ * that may occur. ++ * ++ * All functions and global variables are prefixed with "modeset_*" in this ++ * file. So it should be clear whether a function is a local helper or if it is ++ * provided by some external library. ++ */ ++ ++#define _GNU_SOURCE ++#include <errno.h> ++#include <fcntl.h> ++#include <stdbool.h> ++#include <stdint.h> ++#include <stdio.h> ++#include <stdlib.h> ++#include <string.h> ++#include <sys/mman.h> ++#include <time.h> ++#include <unistd.h> ++#include <xf86drm.h> ++#include <xf86drmMode.h> ++ ++struct modeset_dev; ++static int modeset_find_crtc(int fd, drmModeRes *res, drmModeConnector *conn, ++ struct modeset_dev *dev); ++static int modeset_create_fb(int fd, struct modeset_dev *dev); ++static int modeset_setup_dev(int fd, drmModeRes *res, drmModeConnector *conn, ++ struct modeset_dev *dev); ++static int modeset_open(int *out, const char *node); ++static int modeset_prepare(int fd); ++static void modeset_draw(void); ++static void modeset_cleanup(int fd); ++ ++/* ++ * When the linux kernel detects a graphics-card on your machine, it loads the ++ * correct device driver (located in kernel-tree at ./drivers/gpu/drm/<xy>) and ++ * provides two character-devices to control it. Udev (or whatever hotplugging ++ * application you use) will create them as: ++ * /dev/dri/card0 ++ * /dev/dri/controlID64 ++ * We only need the first one. You can hard-code this path into your application ++ * like we do here, but it is recommended to use libudev with real hotplugging ++ * and multi-seat support. However, this is beyond the scope of this document. ++ * Also note that if you have multiple graphics-cards, there may also be ++ * /dev/dri/card1, /dev/dri/card2, ... ++ * ++ * We simply use /dev/dri/card0 here but the user can specify another path on ++ * the command line. ++ * ++ * modeset_open(out, node): This small helper function opens the DRM device ++ * which is given as @node. The new fd is stored in @out on success. On failure, ++ * a negative error code is returned. ++ * After opening the file, we also check for the DRM_CAP_DUMB_BUFFER capability. ++ * If the driver supports this capability, we can create simple memory-mapped ++ * buffers without any driver-dependent code. As we want to avoid any radeon, ++ * nvidia, intel, etc. specific code, we depend on DUMB_BUFFERs here. ++ */ ++ ++static int modeset_open(int *out, const char *node) ++{ ++ int fd, ret; ++ uint64_t has_dumb; ++ ++ fd = open(node, O_RDWR | O_CLOEXEC); ++ if (fd < 0) { ++ ret = -errno; ++ fprintf(stderr, "cannot open '%s': %m\n", node); ++ return ret; ++ } ++ ++ if (drmGetCap(fd, DRM_CAP_DUMB_BUFFER, &has_dumb) < 0 || ++ !has_dumb) { ++ fprintf(stderr, "drm device '%s' does not support dumb buffers\n", ++ node); ++ close(fd); ++ return -EOPNOTSUPP; ++ } ++ ++ *out = fd; ++ return 0; ++} ++ ++/* ++ * As a next step we need to find our available display devices. libdrm provides ++ * a drmModeRes structure that contains all the needed information. We can ++ * retrieve it via drmModeGetResources(fd) and free it via ++ * drmModeFreeResources(res) again. ++ * ++ * A physical connector on your graphics card is called a "connector". You can ++ * plug a monitor into it and control what is displayed. We are definitely ++ * interested in what connectors are currently used, so we simply iterate ++ * through the list of connectors and try to display a test-picture on each ++ * available monitor. ++ * However, this isn't as easy as it sounds. First, we need to check whether the ++ * connector is actually used (a monitor is plugged in and turned on). Then we ++ * need to find a CRTC that can control this connector. CRTCs are described ++ * later on. After that we create a framebuffer object. If we have all this, we ++ * can mmap() the framebuffer and draw a test-picture into it. Then we can tell ++ * the DRM device to show the framebuffer on the given CRTC with the selected ++ * connector. ++ * ++ * As we want to draw moving pictures on the framebuffer, we actually have to ++ * remember all these settings. Therefore, we create one "struct modeset_dev" ++ * object for each connector+crtc+framebuffer pair that we successfully ++ * initialized and push it into the global device-list. ++ * ++ * Each field of this structure is described when it is first used. But as a ++ * summary: ++ * "struct modeset_dev" contains: { ++ * - @next: points to the next device in the single-linked list ++ * ++ * - @width: width of our buffer object ++ * - @height: height of our buffer object ++ * - @stride: stride value of our buffer object ++ * - @size: size of the memory mapped buffer ++ * - @handle: a DRM handle to the buffer object that we can draw into ++ * - @map: pointer to the memory mapped buffer ++ * ++ * - @mode: the display mode that we want to use ++ * - @fb: a framebuffer handle with our buffer object as scanout buffer ++ * - @conn: the connector ID that we want to use with this buffer ++ * - @crtc: the crtc ID that we want to use with this connector ++ * - @saved_crtc: the configuration of the crtc before we changed it. We use it ++ * so we can restore the same mode when we exit. ++ * } ++ */ ++ ++struct modeset_dev { ++ struct modeset_dev *next; ++ ++ uint32_t width; ++ uint32_t height; ++ uint32_t stride; ++ uint32_t size; ++ uint32_t handle; ++ uint8_t *map; ++ ++ drmModeModeInfo mode; ++ uint32_t fb; ++ uint32_t conn; ++ uint32_t crtc; ++ drmModeCrtc *saved_crtc; ++}; ++ ++static struct modeset_dev *modeset_list = NULL; ++ ++/* ++ * So as next step we need to actually prepare all connectors that we find. We ++ * do this in this little helper function: ++ * ++ * modeset_prepare(fd): This helper function takes the DRM fd as argument and ++ * then simply retrieves the resource-info from the device. It then iterates ++ * through all connectors and calls other helper functions to initialize this ++ * connector (described later on). ++ * If the initialization was successful, we simply add this object as new device ++ * into the global modeset device list. ++ * ++ * The resource-structure contains a list of all connector-IDs. We use the ++ * helper function drmModeGetConnector() to retrieve more information on each ++ * connector. After we are done with it, we free it again with ++ * drmModeFreeConnector(). ++ * Our helper modeset_setup_dev() returns -ENOENT if the connector is currently ++ * unused and no monitor is plugged in. So we can ignore this connector. ++ */ ++ ++static int modeset_prepare(int fd) ++{ ++ drmModeRes *res; ++ drmModeConnector *conn; ++ unsigned int i; ++ struct modeset_dev *dev; ++ int ret; ++ ++ /* retrieve resources */ ++ res = drmModeGetResources(fd); ++ if (!res) { ++ fprintf(stderr, "cannot retrieve DRM resources (%d): %m\n", ++ errno); ++ return -errno; ++ } ++ ++ /* iterate all connectors */ ++ for (i = 0; i < res->count_connectors; ++i) { ++ /* get information for each connector */ ++ conn = drmModeGetConnector(fd, res->connectors[i]); ++ if (!conn) { ++ fprintf(stderr, "cannot retrieve DRM connector %u:%u (%d): %m\n", ++ i, res->connectors[i], errno); ++ continue; ++ } ++ ++ /* create a device structure */ ++ dev = malloc(sizeof(*dev)); ++ memset(dev, 0, sizeof(*dev)); ++ dev->conn = conn->connector_id; ++ ++ /* call helper function to prepare this connector */ ++ ret = modeset_setup_dev(fd, res, conn, dev); ++ if (ret) { ++ if (ret != -ENOENT) { ++ errno = -ret; ++ fprintf(stderr, "cannot setup device for connector %u:%u (%d): %m\n", ++ i, res->connectors[i], errno); ++ } ++ free(dev); ++ drmModeFreeConnector(conn); ++ continue; ++ } ++ ++ /* free connector data and link device into global list */ ++ drmModeFreeConnector(conn); ++ dev->next = modeset_list; ++ modeset_list = dev; ++ } ++ ++ /* free resources again */ ++ drmModeFreeResources(res); ++ return 0; ++} ++ ++/* ++ * Now we dig deeper into setting up a single connector. As described earlier, ++ * we need to check several things first: ++ * * If the connector is currently unused, that is, no monitor is plugged in, ++ * then we can ignore it. ++ * * We have to find a suitable resolution and refresh-rate. All this is ++ * available in drmModeModeInfo structures saved for each crtc. We simply ++ * use the first mode that is available. This is always the mode with the ++ * highest resolution. ++ * A more sophisticated mode-selection should be done in real applications, ++ * though. ++ * * Then we need to find an CRTC that can drive this connector. A CRTC is an ++ * internal resource of each graphics-card. The number of CRTCs controls how ++ * many connectors can be controlled indepedently. That is, a graphics-cards ++ * may have more connectors than CRTCs, which means, not all monitors can be ++ * controlled independently. ++ * There is actually the possibility to control multiple connectors via a ++ * single CRTC if the monitors should display the same content. However, we ++ * do not make use of this here. ++ * So think of connectors as pipelines to the connected monitors and the ++ * CRTCs are the controllers that manage which data goes to which pipeline. ++ * If there are more pipelines than CRTCs, then we cannot control all of ++ * them at the same time. ++ * * We need to create a framebuffer for this connector. A framebuffer is a ++ * memory buffer that we can write XRGB32 data into. So we use this to ++ * render our graphics and then the CRTC can scan-out this data from the ++ * framebuffer onto the monitor. ++ */ ++ ++static int modeset_setup_dev(int fd, drmModeRes *res, drmModeConnector *conn, ++ struct modeset_dev *dev) ++{ ++ int ret; ++ ++ /* check if a monitor is connected */ ++ if (conn->connection != DRM_MODE_CONNECTED) { ++ fprintf(stderr, "ignoring unused connector %u\n", ++ conn->connector_id); ++ return -ENOENT; ++ } ++ ++ /* check if there is at least one valid mode */ ++ if (conn->count_modes == 0) { ++ fprintf(stderr, "no valid mode for connector %u\n", ++ conn->connector_id); ++ return -EFAULT; ++ } ++ ++ /* copy the mode information into our device structure */ ++ memcpy(&dev->mode, &conn->modes[0], sizeof(dev->mode)); ++ dev->width = conn->modes[0].hdisplay; ++ dev->height = conn->modes[0].vdisplay; ++ fprintf(stderr, "mode for connector %u is %ux%u\n", ++ conn->connector_id, dev->width, dev->height); ++ ++ /* find a crtc for this connector */ ++ ret = modeset_find_crtc(fd, res, conn, dev); ++ if (ret) { ++ fprintf(stderr, "no valid crtc for connector %u\n", ++ conn->connector_id); ++ return ret; ++ } ++ ++ /* create a framebuffer for this CRTC */ ++ ret = modeset_create_fb(fd, dev); ++ if (ret) { ++ fprintf(stderr, "cannot create framebuffer for connector %u\n", ++ conn->connector_id); ++ return ret; ++ } ++ ++ return 0; ++} ++ ++/* ++ * modeset_find_crtc(fd, res, conn, dev): This small helper tries to find a ++ * suitable CRTC for the given connector. We have actually have to introduce one ++ * more DRM object to make this more clear: Encoders. ++ * Encoders help the CRTC to convert data from a framebuffer into the right ++ * format that can be used for the chosen connector. We do not have to ++ * understand any more of these conversions to make use of it. However, you must ++ * know that each connector has a limited list of encoders that it can use. And ++ * each encoder can only work with a limited list of CRTCs. So what we do is ++ * trying each encoder that is available and looking for a CRTC that this ++ * encoder can work with. If we find the first working combination, we are happy ++ * and write it into the @dev structure. ++ * But before iterating all available encoders, we first try the currently ++ * active encoder+crtc on a connector to avoid a full modeset. ++ * ++ * However, before we can use a CRTC we must make sure that no other device, ++ * that we setup previously, is already using this CRTC. Remember, we can only ++ * drive one connector per CRTC! So we simply iterate through the "modeset_list" ++ * of previously setup devices and check that this CRTC wasn't used before. ++ * Otherwise, we continue with the next CRTC/Encoder combination. ++ */ ++ ++static int modeset_find_crtc(int fd, drmModeRes *res, drmModeConnector *conn, ++ struct modeset_dev *dev) ++{ ++ drmModeEncoder *enc; ++ unsigned int i, j; ++ int32_t crtc; ++ struct modeset_dev *iter; ++ ++ /* first try the currently conected encoder+crtc */ ++ if (conn->encoder_id) ++ enc = drmModeGetEncoder(fd, conn->encoder_id); ++ else ++ enc = NULL; ++ ++ if (enc) { ++ if (enc->crtc_id) { ++ crtc = enc->crtc_id; ++ for (iter = modeset_list; iter; iter = iter->next) { ++ if (iter->crtc == crtc) { ++ crtc = -1; ++ break; ++ } ++ } ++ ++ if (crtc >= 0) { ++ drmModeFreeEncoder(enc); ++ dev->crtc = crtc; ++ return 0; ++ } ++ } ++ ++ drmModeFreeEncoder(enc); ++ } ++ ++ /* If the connector is not currently bound to an encoder or if the ++ * encoder+crtc is already used by another connector (actually unlikely ++ * but lets be safe), iterate all other available encoders to find a ++ * matching CRTC. */ ++ for (i = 0; i < conn->count_encoders; ++i) { ++ enc = drmModeGetEncoder(fd, conn->encoders[i]); ++ if (!enc) { ++ fprintf(stderr, "cannot retrieve encoder %u:%u (%d): %m\n", ++ i, conn->encoders[i], errno); ++ continue; ++ } ++ ++ /* iterate all global CRTCs */ ++ for (j = 0; j < res->count_crtcs; ++j) { ++ /* check whether this CRTC works with the encoder */ ++ if (!(enc->possible_crtcs & (1 << j))) ++ continue; ++ ++ /* check that no other device already uses this CRTC */ ++ crtc = res->crtcs[j]; ++ for (iter = modeset_list; iter; iter = iter->next) { ++ if (iter->crtc == crtc) { ++ crtc = -1; ++ break; ++ } ++ } ++ ++ /* we have found a CRTC, so save it and return */ ++ if (crtc >= 0) { ++ drmModeFreeEncoder(enc); ++ dev->crtc = crtc; ++ return 0; ++ } ++ } ++ ++ drmModeFreeEncoder(enc); ++ } ++ ++ fprintf(stderr, "cannot find suitable CRTC for connector %u\n", ++ conn->connector_id); ++ return -ENOENT; ++} ++ ++/* ++ * modeset_create_fb(fd, dev): After we have found a crtc+connector+mode ++ * combination, we need to actually create a suitable framebuffer that we can ++ * use with it. There are actually two ways to do that: ++ * * We can create a so called "dumb buffer". This is a buffer that we can ++ * memory-map via mmap() and every driver supports this. We can use it for ++ * unaccelerated software rendering on the CPU. ++ * * We can use libgbm to create buffers available for hardware-acceleration. ++ * libgbm is an abstraction layer that creates these buffers for each ++ * available DRM driver. As there is no generic API for this, each driver ++ * provides its own way to create these buffers. ++ * We can then use such buffers to create OpenGL contexts with the mesa3D ++ * library. ++ * We use the first solution here as it is much simpler and doesn't require any ++ * external libraries. However, if you want to use hardware-acceleration via ++ * OpenGL, it is actually pretty easy to create such buffers with libgbm and ++ * libEGL. But this is beyond the scope of this document. ++ * ++ * So what we do is requesting a new dumb-buffer from the driver. We specify the ++ * same size as the current mode that we selected for the connector. ++ * Then we request the driver to prepare this buffer for memory mapping. After ++ * that we perform the actual mmap() call. So we can now access the framebuffer ++ * memory directly via the dev->map memory map. ++ */ ++ ++static int modeset_create_fb(int fd, struct modeset_dev *dev) ++{ ++ struct drm_mode_create_dumb creq; ++ struct drm_mode_destroy_dumb dreq; ++ struct drm_mode_map_dumb mreq; ++ int ret; ++ ++ /* create dumb buffer */ ++ memset(&creq, 0, sizeof(creq)); ++ creq.width = dev->width; ++ creq.height = dev->height; ++ creq.bpp = 32; ++ ret = drmIoctl(fd, DRM_IOCTL_MODE_CREATE_DUMB, &creq); ++ if (ret < 0) { ++ fprintf(stderr, "cannot create dumb buffer (%d): %m\n", ++ errno); ++ return -errno; ++ } ++ dev->stride = creq.pitch; ++ dev->size = creq.size; ++ dev->handle = creq.handle; ++ ++ /* create framebuffer object for the dumb-buffer */ ++ ret = drmModeAddFB(fd, dev->width, dev->height, 24, 32, dev->stride, ++ dev->handle, &dev->fb); ++ if (ret) { ++ fprintf(stderr, "cannot create framebuffer (%d): %m\n", ++ errno); ++ ret = -errno; ++ goto err_destroy; ++ } ++ ++ /* prepare buffer for memory mapping */ ++ memset(&mreq, 0, sizeof(mreq)); ++ mreq.handle = dev->handle; ++ ret = drmIoctl(fd, DRM_IOCTL_MODE_MAP_DUMB, &mreq); ++ if (ret) { ++ fprintf(stderr, "cannot map dumb buffer (%d): %m\n", ++ errno); ++ ret = -errno; ++ goto err_fb; ++ } ++ ++ /* perform actual memory mapping */ ++ dev->map = mmap(0, dev->size, PROT_READ | PROT_WRITE, MAP_SHARED, ++ fd, mreq.offset); ++ if (dev->map == MAP_FAILED) { ++ fprintf(stderr, "cannot mmap dumb buffer (%d): %m\n", ++ errno); ++ ret = -errno; ++ goto err_fb; ++ } ++ ++ /* clear the framebuffer to 0 */ ++ memset(dev->map, 0, dev->size); ++ ++ return 0; ++ ++err_fb: ++ drmModeRmFB(fd, dev->fb); ++err_destroy: ++ memset(&dreq, 0, sizeof(dreq)); ++ dreq.handle = dev->handle; ++ drmIoctl(fd, DRM_IOCTL_MODE_DESTROY_DUMB, &dreq); ++ return ret; ++} ++ ++/* ++ * Finally! We have a connector with a suitable CRTC. We know which mode we want ++ * to use and we have a framebuffer of the correct size that we can write to. ++ * There is nothing special left to do. We only have to program the CRTC to ++ * connect each new framebuffer to each selected connector for each combination ++ * that we saved in the global modeset_list. ++ * This is done with a call to drmModeSetCrtc(). ++ * ++ * So we are ready for our main() function. First we check whether the user ++ * specified a DRM device on the command line, otherwise we use the default ++ * /dev/dri/card0. Then we open the device via modeset_open(). modeset_prepare() ++ * prepares all connectors and we can loop over "modeset_list" and call ++ * drmModeSetCrtc() on every CRTC/connector combination. ++ * ++ * But printing empty black pages is boring so we have another helper function ++ * modeset_draw() that draws some colors into the framebuffer for 5 seconds and ++ * then returns. And then we have all the cleanup functions which correctly free ++ * all devices again after we used them. All these functions are described below ++ * the main() function. ++ * ++ * As a side note: drmModeSetCrtc() actually takes a list of connectors that we ++ * want to control with this CRTC. We pass only one connector, though. As ++ * explained earlier, if we used multiple connectors, then all connectors would ++ * have the same controlling framebuffer so the output would be cloned. This is ++ * most often not what you want so we avoid explaining this feature here. ++ * Furthermore, all connectors will have to run with the same mode, which is ++ * also often not guaranteed. So instead, we only use one connector per CRTC. ++ * ++ * Before calling drmModeSetCrtc() we also save the current CRTC configuration. ++ * This is used in modeset_cleanup() to restore the CRTC to the same mode as was ++ * before we changed it. ++ * If we don't do this, the screen will stay blank after we exit until another ++ * application performs modesetting itself. ++ */ ++ ++int main(int argc, char **argv) ++{ ++ int ret, fd; ++ const char *card; ++ struct modeset_dev *iter; ++ ++ /* check which DRM device to open */ ++ if (argc > 1) ++ card = argv[1]; ++ else ++ card = "/dev/dri/card0"; ++ ++ fprintf(stderr, "using card '%s'\n", card); ++ ++ /* open the DRM device */ ++ ret = modeset_open(&fd, card); ++ if (ret) ++ goto out_return; ++ ++ /* prepare all connectors and CRTCs */ ++ ret = modeset_prepare(fd); ++ if (ret) ++ goto out_close; ++ ++ /* perform actual modesetting on each found connector+CRTC */ ++ for (iter = modeset_list; iter; iter = iter->next) { ++ iter->saved_crtc = drmModeGetCrtc(fd, iter->crtc); ++ ret = drmModeSetCrtc(fd, iter->crtc, iter->fb, 0, 0, ++ &iter->conn, 1, &iter->mode); ++ if (ret) ++ fprintf(stderr, "cannot set CRTC for connector %u (%d): %m\n", ++ iter->conn, errno); ++ } ++ ++ /* draw some colors for 5seconds */ ++ modeset_draw(); ++ ++ /* cleanup everything */ ++ modeset_cleanup(fd); ++ ++ ret = 0; ++ ++out_close: ++ close(fd); ++out_return: ++ if (ret) { ++ errno = -ret; ++ fprintf(stderr, "modeset failed with error %d: %m\n", errno); ++ } else { ++ fprintf(stderr, "exiting\n"); ++ } ++ return ret; ++} ++ ++/* ++ * A short helper function to compute a changing color value. No need to ++ * understand it. ++ */ ++ ++static uint8_t next_color(bool *up, uint8_t cur, unsigned int mod) ++{ ++ uint8_t next; ++ ++ next = cur + (*up ? 1 : -1) * (rand() % mod); ++ if ((*up && next < cur) || (!*up && next > cur)) { ++ *up = !*up; ++ next = cur; ++ } ++ ++ return next; ++} ++ ++/* ++ * modeset_draw(): This draws a solid color into all configured framebuffers. ++ * Every 100ms the color changes to a slightly different color so we get some ++ * kind of smoothly changing color-gradient. ++ * ++ * The color calculation can be ignored as it is pretty boring. So the ++ * interesting stuff is iterating over "modeset_list" and then through all lines ++ * and width. We then set each pixel individually to the current color. ++ * ++ * We do this 50 times as we sleep 100ms after each redraw round. This makes ++ * 50*100ms = 5000ms = 5s so it takes about 5seconds to finish this loop. ++ * ++ * Please note that we draw directly into the framebuffer. This means that you ++ * will see flickering as the monitor might refresh while we redraw the screen. ++ * To avoid this you would need to use two framebuffers and a call to ++ * drmModeSetCrtc() to switch between both buffers. ++ * You can also use drmModePageFlip() to do a vsync'ed pageflip. But this is ++ * beyond the scope of this document. ++ */ ++ ++static void modeset_draw(void) ++{ ++ uint8_t r, g, b; ++ bool r_up, g_up, b_up; ++ unsigned int i, j, k, off; ++ struct modeset_dev *iter; ++ ++ srand(time(NULL)); ++ r = rand() % 0xff; ++ g = rand() % 0xff; ++ b = rand() % 0xff; ++ r_up = g_up = b_up = true; ++ ++ for (i = 0; i < 50; ++i) { ++ r = next_color(&r_up, r, 20); ++ g = next_color(&g_up, g, 10); ++ b = next_color(&b_up, b, 5); ++ ++ for (iter = modeset_list; iter; iter = iter->next) { ++ for (j = 0; j < iter->height; ++j) { ++ for (k = 0; k < iter->width; ++k) { ++ off = iter->stride * j + k * 4; ++ *(uint32_t*)&iter->map[off] = ++ (r << 16) | (g << 8) | b; ++ } ++ } ++ } ++ ++ usleep(100000); ++ } ++} ++ ++/* ++ * modeset_cleanup(fd): This cleans up all the devices we created during ++ * modeset_prepare(). It resets the CRTCs to their saved states and deallocates ++ * all memory. ++ * It should be pretty obvious how all of this works. ++ */ ++ ++static void modeset_cleanup(int fd) ++{ ++ struct modeset_dev *iter; ++ struct drm_mode_destroy_dumb dreq; ++ ++ while (modeset_list) { ++ /* remove from global list */ ++ iter = modeset_list; ++ modeset_list = iter->next; ++ ++ /* restore saved CRTC configuration */ ++ drmModeSetCrtc(fd, ++ iter->saved_crtc->crtc_id, ++ iter->saved_crtc->buffer_id, ++ iter->saved_crtc->x, ++ iter->saved_crtc->y, ++ &iter->conn, ++ 1, ++ &iter->saved_crtc->mode); ++ drmModeFreeCrtc(iter->saved_crtc); ++ ++ /* unmap buffer */ ++ munmap(iter->map, iter->size); ++ ++ /* delete framebuffer */ ++ drmModeRmFB(fd, iter->fb); ++ ++ /* delete dumb buffer */ ++ memset(&dreq, 0, sizeof(dreq)); ++ dreq.handle = iter->handle; ++ drmIoctl(fd, DRM_IOCTL_MODE_DESTROY_DUMB, &dreq); ++ ++ /* free allocated memory */ ++ free(iter); ++ } ++} ++ ++/* ++ * I hope this was a short but easy overview of the DRM modesetting API. The DRM ++ * API offers much more capabilities including: ++ * - double-buffering or tripple-buffering (or whatever you want) ++ * - vsync'ed page-flips ++ * - hardware-accelerated rendering (for example via OpenGL) ++ * - output cloning ++ * - graphics-clients plus authentication ++ * - DRM planes/overlays/sprites ++ * - ... ++ * If you are interested in these topics, I can currently only redirect you to ++ * existing implementations, including: ++ * - plymouth (which uses dumb-buffers like this example; very easy to understand) ++ * - kmscon (which uses libuterm to do this) ++ * - wayland (very sophisticated DRM renderer; hard to understand fully as it ++ * uses more complicated techniques like DRM planes) ++ * - xserver (very hard to understand as it is split across many files/projects) ++ * ++ * But understanding how modesetting (as described in this document) works, is ++ * essential to understand all further DRM topics. ++ * ++ * Any feedback is welcome. Feel free to use this code freely for your own ++ * documentation or projects. ++ * ++ * - Hosted on http://github.com/dvdhrm/docs ++ * - Written by David Rheinsberg <david.rheinsberg@gmail.com> ++ */ +-- +2.25.1 + |