On 6/16/22 11:13 PM, Jernej Škrabec wrote: > Dne petek, 17. junij 2022 ob 05:03:11 CEST je Samuel Holland napisal(a): >> Hi Jernej, >> >> On 6/16/22 4:32 PM, Jernej Skrabec wrote: >>> Kernel occasionally complains that there is mismatch in segment size >>> when trying to render HW decoded videos and rendering them directly with >>> sun4i DRM driver. >>> >>> Fix that by setting DMA mask and segment size. >>> >>> Signed-off-by: Jernej Skrabec <jernej.skrabec@xxxxxxxxx> >>> --- >>> >>> drivers/gpu/drm/sun4i/sun4i_drv.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/drivers/gpu/drm/sun4i/sun4i_drv.c >>> b/drivers/gpu/drm/sun4i/sun4i_drv.c index 275f7e4a03ae..83f4e87f77f6 >>> 100644 >>> --- a/drivers/gpu/drm/sun4i/sun4i_drv.c >>> +++ b/drivers/gpu/drm/sun4i/sun4i_drv.c >>> @@ -7,6 +7,7 @@ >>> >>> */ >>> >>> #include <linux/component.h> >>> >>> +#include <linux/dma-mapping.h> >>> >>> #include <linux/kfifo.h> >>> #include <linux/module.h> >>> #include <linux/of_graph.h> >>> >>> @@ -367,6 +368,9 @@ static int sun4i_drv_probe(struct platform_device >>> *pdev)> >>> INIT_KFIFO(list.fifo); >>> >>> + dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32)); >> >> Isn't this already the default, from of_dma_configure_id or >> setup_pdev_dma_masks? > > Not sure, I need to check. Looking at the DE2 and DE3 spec to answer your question, I noticed that all of the address fields have a corresponding 8-bit "high address" field, so from a hardware perspective, the DMA mask should be 40 bits. However, currently we do not use these fields, so we are limited to 32 bits. I would suggest we comment that, so I am fine with setting the mask even if redundant, as it provides a good place to add the comment. >>> + dma_set_max_seg_size(&pdev->dev, DMA_BIT_MASK(32)); >> >> This looks like a good change. In fact, I think we need a similar change in >> some other drivers. > > Should be DMA_BIT_MASK(25) as in your other patch? No, that limit is specific to the other DMA engine. I do not see any limit for the display engine. BSP uses sg_tables only for dma-buf, and then it puts the entire framebuffer in one segment. So I think DMA_BIT_MASK(32) (the maximum possible value) is correct. Regards, Samuel
