[PATCH V3] drm/loongson: Error out if no VRAM detected

[Huacai Chen]

If there is no VRAM (it can be true if there is a discreted card, this
is probably a hardware configuration issue in BIOS but it is observed in
GDC-1401 laptop, L71 laptop and some Loongson-3C5000L based servers), we
get such an error and Xorg fails to start:

[  136.401131] loongson 0000:00:06.1: [drm] *ERROR* Requesting(0MiB) failed
[  137.444342] loongson 0000:00:06.1: [drm] *ERROR* Requesting(0MiB) failed
[  138.871166] loongson 0000:00:06.1: [drm] *ERROR* Requesting(0MiB) failed
[  140.444078] loongson 0000:00:06.1: [drm] *ERROR* Requesting(0MiB) failed
[  142.403993] loongson 0000:00:06.1: [drm] *ERROR* Requesting(0MiB) failed
[  143.970625] loongson 0000:00:06.1: [drm] *ERROR* Requesting(0MiB) failed
[  145.862013] loongson 0000:00:06.1: [drm] *ERROR* Requesting(0MiB) failed

So in lsdc_get_dedicated_vram() we error out if no VRAM (or VRAM is less
than 1MB which is also an unusable case) detected.

Tested-by: Xiaotian Wu <wuxiaotian at loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai at loongson.cn>
---
V2: Update commit message.
V3: Return -ENOSPC rather than -ENODEV.

 drivers/gpu/drm/loongson/lsdc_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/loongson/lsdc_drv.c b/drivers/gpu/drm/loongson/lsdc_drv.c
index 89ccc0c43169..d8ff60b46abe 100644
--- a/drivers/gpu/drm/loongson/lsdc_drv.c
+++ b/drivers/gpu/drm/loongson/lsdc_drv.c
@@ -184,7 +184,7 @@ static int lsdc_get_dedicated_vram(struct lsdc_device *ldev,
 	drm_info(ddev, "Dedicated vram start: 0x%llx, size: %uMiB\n",
 		 (u64)base, (u32)(size >> 20));
 
-	return 0;
+	return (size > SZ_1M) ? 0 : -ENOSPC;
 }
 
 static struct lsdc_device *
-- 
2.43.0