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

xiaolei wang <xiaolei.wang@xxxxxxxxxxxxx> · Tue, 1 Oct 2024 20:32:09 +0800

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@xxxxxxxxx>
Signed-off-by: Xiaolei Wang <xiaolei.wang@xxxxxxxxxxxxx>
---

change log

v1:
  https://patchwork.kernel.org/project/dri-devel/patch/20240806104733.2018783-1-xiaolei.wang@xxxxxxxxxxxxx/

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);

      
      
    
  





