Re: [PATCH] drm/etnaviv: fix DMA direction handling for cached read/write buffers

[Sui Jingfeng]

Hi,


On 2024/1/29 18:29, Daniel Stone wrote:

Hi Lucas,

On Fri, 26 Jan 2024 at 17:00, Lucas Stach  wrote:

The dma sync operation needs to be done with DMA_BIDIRECTIONAL when
the BO is prepared for both read and write operations. With the
current inverted if ladder it would only be synced for DMA_FROM_DEVICE.

[...]

  static inline enum dma_data_direction etnaviv_op_to_dma_dir(u32 op)
  {
-   if (op & ETNA_PREP_READ)
+   if (op & (ETNA_PREP_READ | ETNA_PREP_WRITE))
+   return DMA_BIDIRECTIONAL;

This test will always be true for _either_ read or write.



Haha, I think it should be"if ((op & ETNA_PREP_READ) && (op & ETNA_PREP_WRITE))"



Cheers,
Daniel

Re: [PATCH] drm/etnaviv: fix DMA direction handling for cached read/write buffers

[Daniel Stone]

Hi Lucas,

On Fri, 26 Jan 2024 at 17:00, Lucas Stach  wrote:
> The dma sync operation needs to be done with DMA_BIDIRECTIONAL when
> the BO is prepared for both read and write operations. With the
> current inverted if ladder it would only be synced for DMA_FROM_DEVICE.
>
> [...]
>
>  static inline enum dma_data_direction etnaviv_op_to_dma_dir(u32 op)
>  {
> -   if (op & ETNA_PREP_READ)
> +   if (op & (ETNA_PREP_READ | ETNA_PREP_WRITE))
> +   return DMA_BIDIRECTIONAL;

This test will always be true for _either_ read or write.

Cheers,
Daniel

[PATCH] drm/etnaviv: fix DMA direction handling for cached read/write buffers

[Lucas Stach]

The dma sync operation needs to be done with DMA_BIDIRECTIONAL when
the BO is prepared for both read and write operations. With the
current inverted if ladder it would only be synced for DMA_FROM_DEVICE.

Fixes: a8c21a5451d8 ("drm/etnaviv: add initial etnaviv DRM driver")
Signed-off-by: Lucas Stach 
---
 drivers/gpu/drm/etnaviv/etnaviv_gem.c | 8 +---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c 
b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index b5f73502e3dd..d788a27aacb8 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -356,12 +356,14 @@ static void *etnaviv_gem_vmap_impl(struct 
etnaviv_gem_object *obj)
 
 static inline enum dma_data_direction etnaviv_op_to_dma_dir(u32 op)
 {
-   if (op & ETNA_PREP_READ)
+   if (op & (ETNA_PREP_READ | ETNA_PREP_WRITE))
+   return DMA_BIDIRECTIONAL;
+   else if (op & ETNA_PREP_READ)
return DMA_FROM_DEVICE;
else if (op & ETNA_PREP_WRITE)
return DMA_TO_DEVICE;
-   else
-   return DMA_BIDIRECTIONAL;
+
+   return DMA_NONE;
 }
 
 int etnaviv_gem_cpu_prep(struct drm_gem_object *obj, u32 op,
-- 
2.39.2