[Mesa-dev] [PATCH v2] loader: use drmDeviceUseRevisionFile to prevent waking up the GPUs

[Emil Velikov]

From: Emil Velikov <emil.velikov at collabora.com>

Currently the drmGetDevice[s] API parses the config sysfs file to
retrieve the revision field.

That is required since there's no separate file (nor a libudev call
afaict) that can be used. At the same time doing so causes the device to
be awaken, so if an application creates/destroys a GL context multiple
times they can observe noticeable delays. 2-3s in the case of
firefox/thunderbird/chromium + radeon module.

There's a kernel patch on the PCI mailing list, but until then we can
use drmDeviceUseRevisionFile() which will use separate sysfs files and
default to 0 if the revision one is missing.

Since we don't care about the revision id, we can use that.

v2: Add second invocation deep within loader_get_user_preferred_fd()

Cc: "13.0" <mesa-stable at lists.freedesktop.org>
Cc: Mauro Santos <registo.mailling at gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98502
Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
---
Just because some platforms use loader_get_user_preferred_fd while
others do not. That in itself happens prior to any other loader_get_*
call
---
 configure.ac        | 2 +-
 src/loader/loader.c | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index d215b63..f529f2cf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -68,7 +68,7 @@ OPENCL_VERSION=1
 AC_SUBST([OPENCL_VERSION])
 
 dnl Versions for external dependencies
-LIBDRM_REQUIRED=2.4.66
+LIBDRM_REQUIRED=2.4.72
 LIBDRM_RADEON_REQUIRED=2.4.56
 LIBDRM_AMDGPU_REQUIRED=2.4.63
 LIBDRM_INTEL_REQUIRED=2.4.61
diff --git a/src/loader/loader.c b/src/loader/loader.c
index fe90307..a69d583 100644
--- a/src/loader/loader.c
+++ b/src/loader/loader.c
@@ -145,6 +145,7 @@ static char *drm_get_id_path_tag_for_fd(int fd)
    drmDevicePtr device;
    char *tag;
 
+   drmDeviceUseRevisionFile();
    if (drmGetDevice(fd, &device) != 0)
        return NULL;
 
@@ -275,6 +276,7 @@ drm_get_pci_id_for_fd(int fd, int *vendor_id, int *chip_id)
    drmDevicePtr device;
    int ret;
 
+   drmDeviceUseRevisionFile();
    if (drmGetDevice(fd, &device) == 0) {
       if (device->bustype == DRM_BUS_PCI) {
          *vendor_id = device->deviceinfo.pci->vendor_id;
-- 
2.10.2