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From 9ce172053169bbfd27ef8c18eb50ebac348f5bc2 Mon Sep 17 00:00:00 2001
From: Damian Hobson-Garcia <dhobsong@igel.co.jp>
Date: Mon, 11 Apr 2022 18:50:45 +0900
Subject: [PATCH 1/3] backend-drm: Add method to import DRM fd
Allow the compositor to provide a file descriptor for a
DRM device.
This allows the compositor to bypass the launcher backends
and to get a DRM file descriptor from an external
resource manager, such as one that can create DRM leases,
and pass it to the DRM backend for use.
Having the DRM device management in the compositor allows for
integrating a platform specific resource manager without having
to add extra dependencies to the generic libweston code.
%% original patch: 0001-backend-drm-Add-method-to-import-DRM-fd.patch
---
include/libweston/backend-drm.h | 7 +++
libweston/backend-drm/drm.c | 75 ++++++++++++++++++++++++---------
2 files changed, 63 insertions(+), 19 deletions(-)
diff --git a/include/libweston/backend-drm.h b/include/libweston/backend-drm.h
index af2da4a..2c12b17 100644
--- a/include/libweston/backend-drm.h
+++ b/include/libweston/backend-drm.h
@@ -223,6 +223,13 @@ struct weston_drm_backend_config {
/** Use shadow buffer if using Pixman-renderer. */
bool use_pixman_shadow;
+
+ /** DRM device file descriptor to use
+ *
+ * An openeded DRM device file descriptor. If <0, open a DRM
+ * device in the backend using `specific_device` or heuristics.
+ */
+ int device_fd;
};
#ifdef __cplusplus
diff --git a/libweston/backend-drm/drm.c b/libweston/backend-drm/drm.c
index 4278770..0707db7 100644
--- a/libweston/backend-drm/drm.c
+++ b/libweston/backend-drm/drm.c
@@ -40,6 +40,7 @@
#include <linux/vt.h>
#include <assert.h>
#include <sys/mman.h>
+#include <sys/stat.h>
#include <time.h>
#include <xf86drm.h>
@@ -2670,29 +2671,22 @@ drm_device_changed(struct weston_compositor *compositor,
wl_signal_emit(&compositor->session_signal, compositor);
}
-/**
- * Determines whether or not a device is capable of modesetting. If successful,
- * sets b->drm.fd and b->drm.filename to the opened device.
- */
static bool
-drm_device_is_kms(struct drm_backend *b, struct udev_device *device)
+drm_backend_update_kms_device(struct drm_backend *b, struct udev_device *device,
+ const char *name, int drm_fd)
{
- const char *filename = udev_device_get_devnode(device);
const char *sysnum = udev_device_get_sysnum(device);
dev_t devnum = udev_device_get_devnum(device);
drmModeRes *res;
- int id = -1, fd;
+ int id = -1;
- if (!filename)
+ if (!name)
return false;
- fd = weston_launcher_open(b->compositor->launcher, filename, O_RDWR);
- if (fd < 0)
- return false;
- res = drmModeGetResources(fd);
+ res = drmModeGetResources(drm_fd);
if (!res)
- goto out_fd;
+ return false;
if (res->count_crtcs <= 0 || res->count_connectors <= 0 ||
res->count_encoders <= 0)
@@ -2701,7 +2695,7 @@ drm_device_is_kms(struct drm_backend *b, struct udev_device *device)
if (sysnum)
id = atoi(sysnum);
if (!sysnum || id < 0) {
- weston_log("couldn't get sysnum for device %s\n", filename);
+ weston_log("couldn't get sysnum for device %s\n", name);
goto out_res;
}
@@ -2711,9 +2705,9 @@ drm_device_is_kms(struct drm_backend *b, struct udev_device *device)
weston_launcher_close(b->compositor->launcher, b->drm.fd);
free(b->drm.filename);
- b->drm.fd = fd;
+ b->drm.fd = drm_fd;
b->drm.id = id;
- b->drm.filename = strdup(filename);
+ b->drm.filename = strdup(name);
b->drm.devnum = devnum;
drmModeFreeResources(res);
@@ -2722,11 +2716,33 @@ drm_device_is_kms(struct drm_backend *b, struct udev_device *device)
out_res:
drmModeFreeResources(res);
-out_fd:
- weston_launcher_close(b->compositor->launcher, fd);
return false;
}
+/**
+ * Determines whether or not a device is capable of modesetting. If successful,
+ * sets b->drm.fd and b->drm.filename to the opened device.
+ */
+static bool
+drm_device_is_kms(struct drm_backend *b, struct udev_device *device)
+{
+ int fd;
+ const char *filename = udev_device_get_devnode(device);
+ if (!filename)
+ return false;
+
+ fd = weston_launcher_open(b->compositor->launcher, filename, O_RDWR);
+ if (fd < 0)
+ return false;
+
+ if (!drm_backend_update_kms_device(b, device, filename, fd)) {
+ weston_launcher_close(b->compositor->launcher, fd);
+ return false;
+ }
+
+ return true;
+}
+
/*
* Find primary GPU
* Some systems may have multiple DRM devices attached to a single seat. This
@@ -2814,6 +2830,25 @@ find_primary_gpu(struct drm_backend *b, const char *seat)
return drm_device;
}
+static struct udev_device *
+import_drm_device_fd(struct drm_backend *b, int fd)
+{
+ struct udev_device *device;
+ struct stat s;
+
+ if (fstat(fd, &s) < 0 || !S_ISCHR(s.st_mode))
+ return NULL;
+
+ device = udev_device_new_from_devnum(b->udev, 'c', s.st_rdev);
+ if (!device)
+ return NULL;
+
+ if (!drm_backend_update_kms_device(b, device, "imported DRM device fd", fd))
+ return NULL;
+
+ return device;
+}
+
static struct udev_device *
open_specific_drm_device(struct drm_backend *b, const char *name)
{
@@ -3038,7 +3073,9 @@ drm_backend_create(struct weston_compositor *compositor,
b->session_listener.notify = session_notify;
wl_signal_add(&compositor->session_signal, &b->session_listener);
- if (config->specific_device)
+ if (config->device_fd > 0)
+ drm_device = import_drm_device_fd(b, config->device_fd);
+ else if (config->specific_device)
drm_device = open_specific_drm_device(b, config->specific_device);
else
drm_device = find_primary_gpu(b, seat_id);
--
2.17.1
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