From: jsg <jsg@openbsd.org>
Date: Thu, 27 Jan 2022 23:10:02 +0000 (+0000)
Subject: drm/amdgpu: fixup bad vram size on gmc v8
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=8f5eade93abdfc513ba9a9bcd18f48a997104bae;p=openbsd

drm/amdgpu: fixup bad vram size on gmc v8

From Zongmin Zhou
493b87970061f044c5cf795cfd1d679d114844ed in linux 5.15.y/5.15.17
11544d77e3974924c5a9c8a8320b996a3e9b2f8b in mainline linux
---

diff --git a/sys/dev/pci/drm/amd/amdgpu/gmc_v8_0.c b/sys/dev/pci/drm/amd/amdgpu/gmc_v8_0.c
index 339ffd9b691..587206dd388 100644
--- a/sys/dev/pci/drm/amd/amdgpu/gmc_v8_0.c
+++ b/sys/dev/pci/drm/amd/amdgpu/gmc_v8_0.c
@@ -515,10 +515,10 @@ static void gmc_v8_0_mc_program(struct amdgpu_device *adev)
 static int gmc_v8_0_mc_init(struct amdgpu_device *adev)
 {
 	int r;
+	u32 tmp;
 
 	adev->gmc.vram_width = amdgpu_atombios_get_vram_width(adev);
 	if (!adev->gmc.vram_width) {
-		u32 tmp;
 		int chansize, numchan;
 
 		/* Get VRAM informations */
@@ -562,8 +562,15 @@ static int gmc_v8_0_mc_init(struct amdgpu_device *adev)
 		adev->gmc.vram_width = numchan * chansize;
 	}
 	/* size in MB on si */
-	adev->gmc.mc_vram_size = RREG32(mmCONFIG_MEMSIZE) * 1024ULL * 1024ULL;
-	adev->gmc.real_vram_size = RREG32(mmCONFIG_MEMSIZE) * 1024ULL * 1024ULL;
+	tmp = RREG32(mmCONFIG_MEMSIZE);
+	/* some boards may have garbage in the upper 16 bits */
+	if (tmp & 0xffff0000) {
+		DRM_INFO("Probable bad vram size: 0x%08x\n", tmp);
+		if (tmp & 0xffff)
+			tmp &= 0xffff;
+	}
+	adev->gmc.mc_vram_size = tmp * 1024ULL * 1024ULL;
+	adev->gmc.real_vram_size = adev->gmc.mc_vram_size;
 
 	if (!(adev->flags & AMD_IS_APU)) {
 		r = amdgpu_device_resize_fb_bar(adev);