vdpau: report DRI2 VDPAU driver name as 'sunxi'

Try to load the sunxi cedar kernel module. And if it loads successfully,
then report the DRI2 VDPAU name as 'sunxi'. This allows to use
libvdpau-sunxi without setting the VDPAU_DRIVER environment variable.
Signed-off-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>

src/sunxi_mali_ump_dri2.c

@@ -1074,21 +1074,36 @@ static unsigned long ump_get_size_from_secure_id(ump_secure_id secure_id)
     return size;
 }
 
+static const char *driverNames[1] = {
+    "lima" /* DRI2DriverDRI */
+};
+
+static const char *driverNamesWithVDPAU[2] = {
+    "lima", /* DRI2DriverDRI */
+    "sunxi" /* DRI2DriverVDPAU */
+};
+
 SunxiMaliDRI2 *SunxiMaliDRI2_Init(ScreenPtr pScreen,
                                   Bool      bUseOverlay,
                                   Bool      bSwapbuffersWait)
 {
     int drm_fd;
-    DRI2InfoRec info;
+    DRI2InfoRec info = { 0 };
     SunxiMaliDRI2 *mali;
     ScrnInfoPtr pScrn = xf86Screens[pScreen->myNum];
     sunxi_disp_t *disp = SUNXI_DISP(pScrn);
+    Bool have_sunxi_cedar = TRUE;
 
     if (!xf86LoadKernelModule("mali"))
         xf86DrvMsg(pScreen->myNum, X_INFO, "can't load 'mali' kernel module\n");
     if (!xf86LoadKernelModule("mali_drm"))
         xf86DrvMsg(pScreen->myNum, X_INFO, "can't load 'mali_drm' kernel module\n");
 
+    if (!xf86LoadKernelModule("sunxi_cedar_mod")) {
+        xf86DrvMsg(pScreen->myNum, X_INFO, "can't load 'sunxi_cedar_mod' kernel module\n");
+        have_sunxi_cedar = FALSE;
+    }
+
     if (!xf86LoadSubModule(xf86Screens[pScreen->myNum], "dri2"))
         return NULL;
 
@@ -1174,9 +1189,18 @@ SunxiMaliDRI2 *SunxiMaliDRI2_Init(ScreenPtr pScreen,
     xf86DrvMsg(pScreen->myNum, X_INFO, "Wait on SwapBuffers? %s\n",
                bSwapbuffersWait ? "enabled" : "disabled");
 
-    info.version = 3;
+    info.version = 4;
 
-    info.driverName = "lima";
+    if (have_sunxi_cedar) {
+        info.numDrivers = ARRAY_SIZE(driverNamesWithVDPAU);
+        info.driverName = driverNamesWithVDPAU[0];
+        info.driverNames = driverNamesWithVDPAU;
+    }
+    else {
+        info.numDrivers = ARRAY_SIZE(driverNames);
+        info.driverName = driverNames[0];
+        info.driverNames = driverNames;
+    }
     info.deviceName = drmGetDeviceNameFromFd(drm_fd);
     info.fd = drm_fd;