[PATCH v4] drm/etnaviv: Request pages from DMA32 zone on addressing_limited

From: Xiaolei Wang
Date: Tue Oct 01 2024 - 19:35:21 EST


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>
Reviewed-by: Christian Gmeiner <cgmeiner@xxxxxxxxxx>
---
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;"

v4:
drop the HIGHMEM bit only if dma addressing is limited.

drivers/gpu/drm/etnaviv/etnaviv_drv.c | 10 ++++++++++
drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 8 --------
2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
index 6500f3999c5f..19ec67a5a918 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
@@ -538,6 +538,16 @@ static int etnaviv_bind(struct device *dev)
priv->num_gpus = 0;
priv->shm_gfp_mask = GFP_HIGHUSER | __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->shm_gfp_mask &= ~__GFP_HIGHMEM;
+ }
+
priv->cmdbuf_suballoc = etnaviv_cmdbuf_suballoc_new(drm->dev);
if (IS_ERR(priv->cmdbuf_suballoc)) {
dev_err(drm->dev, "Failed to create cmdbuf suballocator\n");
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);
--
2.25.1