drm/msm: Add proper checks for GPU LLCC support

Domain attribute setting for LLCC is guarded by !IS_ERR
check which works fine only when CONFIG_QCOM_LLCC=y but
when it is disabled, the LLCC apis return NULL and that
is not handled by IS_ERR check. Due to this, domain attribute
for LLCC will be set even on GPUs which do not support it
and cause issues, so correct this by using IS_ERR_OR_NULL
checks appropriately. Meanwhile also cleanup comment block
and remove unwanted blank line.

Fixes: 00fd44a1 ("drm/msm: Only enable A6xx LLCC code on A6xx")
Fixes: 474dadb8 ("drm/msm/a6xx: Add support for using system cache(LLC)")
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/a6xx_gpu.c

@@ -1118,7 +1118,7 @@ static void a6xx_llc_slices_init(struct platform_device *pdev,
 	a6xx_gpu->llc_slice = llcc_slice_getd(LLCC_GPU);
 	a6xx_gpu->htw_llc_slice = llcc_slice_getd(LLCC_GPUHTW);
 
-	if (IS_ERR(a6xx_gpu->llc_slice) && IS_ERR(a6xx_gpu->htw_llc_slice))
+	if (IS_ERR_OR_NULL(a6xx_gpu->llc_slice) && IS_ERR_OR_NULL(a6xx_gpu->htw_llc_slice))
 		a6xx_gpu->llc_mmio = ERR_PTR(-EINVAL);
 }
 

drivers/gpu/drm/msm/adreno/adreno_gpu.c

@@ -200,15 +200,15 @@ adreno_iommu_create_address_space(struct msm_gpu *gpu,
 	if (!iommu)
 		return NULL;
 
-
 	if (adreno_is_a6xx(adreno_gpu)) {
 		struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 		struct io_pgtable_domain_attr pgtbl_cfg;
+
 		/*
 		 * This allows GPU to set the bus attributes required to use system
 		 * cache on behalf of the iommu page table walker.
 		 */
-		if (!IS_ERR(a6xx_gpu->htw_llc_slice)) {
+		if (!IS_ERR_OR_NULL(a6xx_gpu->htw_llc_slice)) {
 			pgtbl_cfg.quirks = IO_PGTABLE_QUIRK_ARM_OUTER_WBWA;
 			iommu_domain_set_attr(iommu, DOMAIN_ATTR_IO_PGTABLE_CFG, &pgtbl_cfg);
 		}