[PATCH v3] drm/etnaviv: Request pages from DMA32 zone on addressing_limited

[xiaolei wang]

On 10/1/24 20:17, Lucas Stach wrote:
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> Hi Xiaolei,
>
> Am Dienstag, dem 03.09.2024 um 10:08 +0800 schrieb Xiaolei Wang:
>> 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 at linux.dev>
>> Signed-off-by: Xiaolei Wang<xiaolei.wang at windriver.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;"
> I don't understand this part of the changes in the new version. Why
> should we drop the HIGHMEM bit always and not only in the case where
> dma addressing is limited? This seems overly restrictive.

Makes sense, thanks for your reminder, I will drop the HIGHMEM bit when 
the next version has address limit

     if (dma_addressing_limited(gpu->dev)) {
         priv->shm_gfp_mask |= GFP_DMA32;
         priv->shm_gfp_mask &= ~__GFP_HIGHMEM;
     }

thanks

xiaolei

>
> Regards,
> Lucas
>
>> 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);
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