[Mesa-dev] [PATCH] loader: Add support for platform and host1x busses

[Thierry Reding]

From: Thierry Reding <treding at nvidia.com>

ARM SoCs usually have their DRM/KMS devices on the platform bus, so add
support for this bus in order to allow use of the DRI_PRIME environment
variable with those devices.

While at it, also support the host1x bus, which is effectively the same
but uses an additional layer in the bus hierarchy.

Note that it isn't enough to support the bus that has the rendering GPU
because the loader code will also try to construct an ID path tag for a
scanout-only device if it is the default that is being opened.

The ID path tag for a device can be obtained by running udevadm info on
the device node:

	$ udevadm info /dev/dri/card0

and looking up the ID_PATH_TAG entry in the output.

Signed-off-by: Thierry Reding <treding at nvidia.com>
---
 src/loader/loader.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/src/loader/loader.c b/src/loader/loader.c
index 92b4c5204b19..ca578b8cd232 100644
--- a/src/loader/loader.c
+++ b/src/loader/loader.c
@@ -120,6 +120,33 @@ static char *drm_construct_id_path_tag(drmDevicePtr device)
                    device->businfo.pci->func) < 0) {
          return NULL;
       }
+   } else if (device->bustype == DRM_BUS_PLATFORM ||
+              device->bustype == DRM_BUS_HOST1X) {
+      char *fullname, *name, *address;
+
+      if (device->bustype == DRM_BUS_PLATFORM)
+         fullname = device->businfo.platform->fullname;
+      else
+         fullname = device->businfo.host1x->fullname;
+
+      name = strrchr(fullname, '/');
+      if (!name)
+         name = strdup(fullname);
+      else
+         name = strdup(++name);
+
+      address = strchr(name, '@');
+      if (address) {
+         *address++ = '\0';
+
+         if (asprintf(&tag, "platform-%s_%s", address, name) < 0)
+            tag = NULL;
+      } else {
+         if (asprintf(&tag, "platform-%s", name) < 0)
+            tag = NULL;
+      }
+
+      free(name);
    }
    return tag;
 }
-- 
2.16.2