[PATCH libdrm 1/2] xf86drm: fallback to MODALIAS for OF less platform devices

[Emil Velikov]

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

Some devices can lack OF data or it may not be available in the uevent
file. Fallback to the MODALIAS data in those cases.

We strip any leading "MODALIAS=.*:" thus the resulting information is
compatible with existing code in Mesa.

Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
---
 xf86drm.c | 55 ++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 42 insertions(+), 13 deletions(-)

diff --git a/xf86drm.c b/xf86drm.c
index 10df682b..374734eb 100644
--- a/xf86drm.c
+++ b/xf86drm.c
@@ -3511,15 +3511,28 @@ free_device:
 static int drmParsePlatformBusInfo(int maj, int min, drmPlatformBusInfoPtr info)
 {
 #ifdef __linux__
-    char path[PATH_MAX + 1], *name;
+    char path[PATH_MAX + 1], *name, *foo;
 
     snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device", maj, min);
 
     name = sysfs_uevent_get(path, "OF_FULLNAME");
-    if (!name)
-        return -ENOENT;
+    foo = name;
+    if (!name) {
+        /* If the device lacks OF data, pick the MODALIAS info */
+        name = sysfs_uevent_get(path, "MODALIAS");
+        if (!name)
+            return -ENOENT;
+
+        /* .. and strip the MODALIAS=[platform,usb...]: part. */
+        foo = strrchr(name, ':');
+        if (!foo) {
+            free(name);
+            return -ENOENT;
+        }
+        foo++;
+    }
 
-    strncpy(info->fullname, name, DRM_PLATFORM_DEVICE_NAME_LEN);
+    strncpy(info->fullname, foo, DRM_PLATFORM_DEVICE_NAME_LEN);
     info->fullname[DRM_PLATFORM_DEVICE_NAME_LEN - 1] = '\0';
     free(name);
 
@@ -3534,18 +3547,20 @@ static int drmParsePlatformDeviceInfo(int maj, int min,
                                       drmPlatformDeviceInfoPtr info)
 {
 #ifdef __linux__
-    char path[PATH_MAX + 1], *value;
+    char path[PATH_MAX + 1], *value, *foo;
     unsigned int count, i;
     int err;
 
     snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device", maj, min);
 
     value = sysfs_uevent_get(path, "OF_COMPATIBLE_N");
-    if (!value)
-        return -ENOENT;
-
-    sscanf(value, "%u", &count);
-    free(value);
+    if (value) {
+        sscanf(value, "%u", &count);
+        free(value);
+    } else {
+        /* Assume one entry if the device lack OF data */
+        count = 1;
+    }
 
     info->compatible = calloc(count + 1, sizeof(*info->compatible));
     if (!info->compatible)
@@ -3553,12 +3568,26 @@ static int drmParsePlatformDeviceInfo(int maj, int min,
 
     for (i = 0; i < count; i++) {
         value = sysfs_uevent_get(path, "OF_COMPATIBLE_%u", i);
+        foo = value;
         if (!value) {
-            err = -ENOENT;
-            goto free;
+            /* If the device lacks OF data, pick the MODALIAS info */
+            value = sysfs_uevent_get(path, "MODALIAS");
+            if (!value) {
+                err = -ENOENT;
+                goto free;
+            }
+
+            /* .. and strip the MODALIAS=[platform,usb...]: part. */
+            foo = strrchr(value, ':');
+            if (!foo) {
+                free(value);
+                return -ENOENT;
+            }
+            foo = strdup(foo + 1);
+            free(value);
         }
 
-        info->compatible[i] = value;
+        info->compatible[i] = foo;
     }
 
     return 0;
-- 
2.20.1