Re: [PATCH] drm/ttm: ioremap buffer according to TTM mem caching setting

["Bhardwaj, Rajneesh" <rajneesh.bhardwaj@amd.com>]

I was wondering if a managed version of such API exists but looks like 
none. We only have devm_ioremap_wc but that is valid only for 
PAGE_CACHE_MODE_WC whereas ioremap_cache uses _WB. One more small 
comment below.


Acked-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>

On 3/4/2021 11:04 AM, Oak Zeng wrote:
> If tbo.mem.bus.caching is cached, buffer is intended to be mapped
> as cached from CPU. Map it with ioremap_cache.
>
> This wasn't necessary before as device memory was never mapped
> as cached from CPU side. It becomes necessary for aldebaran as
> device memory is mapped cached from CPU.
>
> Signed-off-by: Oak Zeng <Oak.Zeng@amd.com>
> Reviewed-by: Christian Konig <Christian.Koenig@amd.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo_util.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index 031e581..7429464 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -91,6 +91,10 @@ static int ttm_resource_ioremap(struct ttm_device *bdev,
>   
>   		if (mem->bus.caching == ttm_write_combined)
>   			addr = ioremap_wc(mem->bus.offset, bus_size);
> +#ifdef CONFIG_X86


Please use #if defined (CONFIG_X86)

> +		else if (mem->bus.caching == ttm_cached)
> +			addr = ioremap_cache(mem->bus.offset, bus_size);
> +#endif
>   		else
>   			addr = ioremap(mem->bus.offset, bus_size);
>   		if (!addr) {
> @@ -372,6 +376,11 @@ static int ttm_bo_ioremap(struct ttm_buffer_object *bo,
>   		if (mem->bus.caching == ttm_write_combined)
>   			map->virtual = ioremap_wc(bo->mem.bus.offset + offset,
>   						  size);
> +#ifdef CONFIG_X86
> +		else if (mem->bus.caching == ttm_cached)
> +			map->virtual = ioremap_cache(bo->mem.bus.offset + offset,
> +						  size);
> +#endif
>   		else
>   			map->virtual = ioremap(bo->mem.bus.offset + offset,
>   					       size);
> @@ -490,6 +499,11 @@ int ttm_bo_vmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
>   		else if (mem->bus.caching == ttm_write_combined)
>   			vaddr_iomem = ioremap_wc(mem->bus.offset,
>   						 bo->base.size);
> +		else if (mem->bus.caching == ttm_cached)
> +#ifdef CONFIG_X86
> +			vaddr_iomem = ioremap_cache(mem->bus.offset,
> +						  bo->base.size);
> +#endif
>   		else
>   			vaddr_iomem = ioremap(mem->bus.offset, bo->base.size);
>   
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