drm: implement vaGetDriverNames

v2: Add WSL case

v3: Drop sentinel, use ARRAY_SIZE

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

Author: evelikov

va/drm/va_drm.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2012 Intel Corporation. All Rights Reserved.
+ * Copyright (c) 2023 Emil Velikov
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the
@@ -94,6 +95,21 @@ va_DisplayContextGetDriverNameByIndex(
     return VA_DRM_GetDriverName(ctx, driver_name_ptr, candidate_index);
 }
 
+static VAStatus
+va_DisplayContextGetDriverNames(
+    VADisplayContextP pDisplayContext,
+    char            **drivers,
+    unsigned         *num_drivers
+)
+{
+    VADriverContextP const ctx = pDisplayContext->pDriverContext;
+    VAStatus status = va_DisplayContextConnect(pDisplayContext);
+    if (status != VA_STATUS_SUCCESS)
+        return status;
+
+    return VA_DRM_GetDriverNames(ctx, drivers, num_drivers);
+}
+
 VADisplay
 vaGetDisplayDRM(int fd)
 {
@@ -119,6 +135,7 @@ vaGetDisplayDRM(int fd)
     pDisplayContext->vaDestroy       = va_DisplayContextDestroy;
     pDisplayContext->vaGetNumCandidates = va_DisplayContextGetNumCandidates;
     pDisplayContext->vaGetDriverNameByIndex = va_DisplayContextGetDriverNameByIndex;
+    pDisplayContext->vaGetDriverNames = va_DisplayContextGetDriverNames;
 
     pDriverContext = va_newDriverContext(pDisplayContext);
     if (!pDriverContext)

va/drm/va_drm_utils.c

@@ -2,6 +2,7 @@
  * va_drm_utils.c - VA/DRM Utilities
  *
  * Copyright (c) 2012 Intel Corporation. All Rights Reserved.
+ * Copyright (c) 2023 Emil Velikov
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the
@@ -31,6 +32,8 @@
 #include "va_drm_utils.h"
 #include "va_drmcommon.h"
 
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+
 struct driver_name_map {
     const char *key;
     const char *name;
@@ -148,3 +151,65 @@ VA_DRM_GetDriverName(VADriverContextP ctx, char **driver_name_ptr, int candidate
 
     return VA_STATUS_SUCCESS;
 }
+
+/* Returns the VA driver names and how many they are, for the active display */
+VAStatus
+VA_DRM_GetDriverNames(VADriverContextP ctx, char **drivers, unsigned *num_drivers)
+{
+#define MAX_NAMES 2 // Adjust if needed
+
+    static const struct {
+        const char * const drm_driver;
+        const char * const va_driver[MAX_NAMES];
+    } map[] = {
+        { "i915",       { "iHD", "i965"      } }, // Intel Media and OTC GenX
+        { "pvrsrvkm",   { "pvr"              } }, // Intel UMG PVR
+        { "radeon",     { "r600", "radeonsi" } }, // Mesa Gallium
+        { "amdgpu",     { "radeonsi"         } }, // Mesa Gallium
+        { "WSL",        { "d3d12"            } }, // Mesa Gallium
+        { "nvidia-drm", { "nvidia"           } }, // Unofficial NVIDIA
+    };
+
+    const struct drm_state * const drm_state = ctx->drm_state;
+    char *drm_driver;
+    unsigned count = 0;
+
+    drm_driver = va_DRM_GetDrmDriverName(drm_state->fd);
+    if (!drm_driver)
+        return VA_STATUS_ERROR_UNKNOWN;
+
+    /* Map vgem to WSL2 for Windows subsystem for linux */
+    struct utsname sysinfo = {};
+    if (!strncmp(drm_driver, "vgem", 4) && uname(&sysinfo) >= 0 &&
+        strstr(sysinfo.release, "WSL")) {
+        free(drm_driver);
+        drm_driver = strdup("WSL");
+        if (!drm_driver)
+            return VA_STATUS_ERROR_UNKNOWN;
+    }
+
+    for (unsigned i = 0; i < ARRAY_SIZE(map); i++) {
+        if (strcmp(map[i].drm_driver, drm_driver) == 0) {
+            const char * const *va_drivers = map[i].va_driver;
+
+            while (va_drivers[count]) {
+                if (count < MAX_NAMES && count < *num_drivers)
+                    drivers[count] = strdup(va_drivers[count]);
+                count++;
+            }
+            break;
+        }
+    }
+
+    /* Fallback to the drm driver, if there's no va equivalent in the map. */
+    if (!count) {
+        drivers[count] = drm_driver;
+        count++;
+    } else {
+        free(drm_driver);
+    }
+
+    *num_drivers = count;
+
+    return VA_STATUS_SUCCESS;
+}

va/drm/va_drm_utils.h

@@ -41,9 +41,11 @@
 #ifdef __cplusplus
 extern "C" {
 #endif
+
 DLL_HIDDEN
 VAStatus
 VA_DRM_GetNumCandidates(VADriverContextP ctx, int * num_candidates);
+
 /**
  * \brief Returns the VA driver name for the active display.
  *
@@ -66,6 +68,10 @@ DLL_HIDDEN
 VAStatus
 VA_DRM_GetDriverName(VADriverContextP ctx, char **driver_name_ptr, int candidate_index);
 
+DLL_HIDDEN
+VAStatus
+VA_DRM_GetDriverNames(VADriverContextP ctx, char **drivers, unsigned *num_drivers);
+
 /**@}*/
 
 #ifdef __cplusplus