linux-kernel - Re: [PATCH v3] drm/etnaviv: Request pages from DMA32 zone on addressing

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Message-ID: <b0c651c1-acd6-4ca0-8791-f6bc16821a1e@linux.dev>
Date: Wed, 11 Sep 2024 17:37:02 +0800
From: Sui Jingfeng <sui.jingfeng@...ux.dev>
To: Xiaolei Wang <xiaolei.wang@...driver.com>, l.stach@...gutronix.de,
 linux+etnaviv@...linux.org.uk, christian.gmeiner@...il.com,
 airlied@...il.com, daniel@...ll.ch
Cc: etnaviv@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] drm/etnaviv: Request pages from DMA32 zone on
 addressing_limited

Humble ping ?

On 9/3/24 10:08, Xiaolei Wang wrote:
> Remove __GFP_HIGHMEM when requesting a page from DMA32 zone,
> and since all vivante GPUs in the system will share the same
> DMA constraints, move the check of whether to get a page from
> DMA32 to etnaviv_bind().
> 
> Fixes: b72af445cd38 ("drm/etnaviv: request pages from DMA32 zone when needed")
> Suggested-by: Sui Jingfeng <sui.jingfeng@...ux.dev>
> Signed-off-by: Xiaolei Wang <xiaolei.wang@...driver.com>
> ---
> 
> change log
> 
> v1:
>    https://patchwork.kernel.org/project/dri-devel/patch/20240806104733.2018783-1-xiaolei.wang@windriver.com/
> 
> v2:
>    Modify the issue of not retaining GFP_USER in v1 and update the commit log.
> 
> v3:
>    Use "priv->shm_gfp_mask = GFP_USER | __GFP_RETRY_MAYFAIL | __GFP_NOWARN;"
> instead of
>    "priv->shm_gfp_mask = GFP_HIGHUSER | __GFP_RETRY_MAYFAIL | __GFP_NOWARN;"
> and move the check of whether to get a page from DMA32 to etnaviv_bind().
> 
>   drivers/gpu/drm/etnaviv/etnaviv_drv.c | 10 +++++++++-
>   drivers/gpu/drm/etnaviv/etnaviv_gpu.c |  8 --------
>   2 files changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> index 6500f3999c5f..8cb2c3ec8e5d 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> @@ -536,7 +536,15 @@ static int etnaviv_bind(struct device *dev)
>   	mutex_init(&priv->gem_lock);
>   	INIT_LIST_HEAD(&priv->gem_list);
>   	priv->num_gpus = 0;
> -	priv->shm_gfp_mask = GFP_HIGHUSER | __GFP_RETRY_MAYFAIL | __GFP_NOWARN;
> +	priv->shm_gfp_mask = GFP_USER | __GFP_RETRY_MAYFAIL | __GFP_NOWARN;
> +
> +	/*
> +	 * If the GPU is part of a system with DMA addressing limitations,
> +	 * request pages for our SHM backend buffers from the DMA32 zone to
> +	 * hopefully avoid performance killing SWIOTLB bounce buffering.
> +	 */
> +	if (dma_addressing_limited(dev))
> +		priv->shm_gfp_mask |= GFP_DMA32;
>   
>   	priv->cmdbuf_suballoc = etnaviv_cmdbuf_suballoc_new(drm->dev);
>   	if (IS_ERR(priv->cmdbuf_suballoc)) {
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> index 7c7f97793ddd..5e753dd42f72 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> @@ -839,14 +839,6 @@ int etnaviv_gpu_init(struct etnaviv_gpu *gpu)
>   	if (ret)
>   		goto fail;
>   
> -	/*
> -	 * If the GPU is part of a system with DMA addressing limitations,
> -	 * request pages for our SHM backend buffers from the DMA32 zone to
> -	 * hopefully avoid performance killing SWIOTLB bounce buffering.
> -	 */
> -	if (dma_addressing_limited(gpu->dev))
> -		priv->shm_gfp_mask |= GFP_DMA32;
> -
>   	/* Create buffer: */
>   	ret = etnaviv_cmdbuf_init(priv->cmdbuf_suballoc, &gpu->buffer,
>   				  PAGE_SIZE);

-- 
Best regards
Sui