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gbm: Load backend based on DRM device driver name 

After attempting to use the GBM backend specified by the user
via an environment variable, if any, but before falling back
to the built-in GBM backends, attempt to dlopen
libg<DRM driver name>_gbm.so in the GBM backend library search
path (Defaults to "$libdir/gbm") and initialize a device using
it. This enables automatic backend discovery for devices that
do not provide a DRI driver.

Signed-off-by: James Jones <jajones@nvidia.com>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9902>
This commit is contained in:
James Jones 2021-03-18 15:36:07 -07:00 committed by Marge Bot
parent 68902822d6
commit 21ce1ca846
1 changed files with 29 additions and 1 deletions
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30
src/gbm/main/backend.c
View File

@ -34,6 +34,7 @@
#include <limits.h>
#include <assert.h>
#include <dlfcn.h>
#include <xf86drm.h>
#include "loader.h"
#include "backend.h"
@ -53,6 +54,7 @@ static const struct gbm_backend_desc builtin_backends[] = {
{ "dri", &gbm_dri_backend },
};
#define BACKEND_LIB_SUFFIX "_gbm"
static const char *backend_search_path_vars[] = {
"GBM_BACKENDS_PATH",
NULL
@ -161,7 +163,7 @@ find_backend(const char *name, int fd)
}
if (name && !dev) {
lib = loader_open_driver_lib(name, "_gbm",
lib = loader_open_driver_lib(name, BACKEND_LIB_SUFFIX,
backend_search_path_vars,
DEFAULT_BACKENDS_PATH,
true);
@ -186,6 +188,29 @@ override_backend(int fd)
return dev;
}
static struct gbm_device *
backend_from_driver_name(int fd)
{
struct gbm_device *dev = NULL;
drmVersionPtr v = drmGetVersion(fd);
void *lib;
if (!v)
return NULL;
lib = loader_open_driver_lib(v->name, BACKEND_LIB_SUFFIX,
backend_search_path_vars,
DEFAULT_BACKENDS_PATH,
false);
if (lib)
dev = load_backend(lib, fd, v->name);
drmFreeVersion(v);
return dev;
}
struct gbm_device *
_gbm_create_device(int fd)
{
@ -193,6 +218,9 @@ _gbm_create_device(int fd)
dev = override_backend(fd);
if (!dev)
dev = backend_from_driver_name(fd);
if (!dev)
dev = find_backend(NULL, fd);