Dne torek, 21. junij 2022 ob 02:20:11 CEST je Samuel Holland napisal(a): > Hi Jernej, > > On 6/20/22 1:28 PM, Jernej Škrabec wrote: > > Dne petek, 17. junij 2022 ob 05:42:09 CEST je Samuel Holland napisal(a): > >> The sun6i DMA engine supports segment sizes up to 2^25-1 bytes. This is > >> explicitly stated in newer SoC documentation (H6, D1), and it is implied > >> in older documentation by the 25-bit width of the "bytes left in the > >> current segment" register field. > > > > At least A10 user manual says 128k max in description for Byte Counter > > register (0x100+N*0x20+0xC), although field size is defined as 23:0, but that's > > still less than 2^25-1. A20 supports only 128k too according to manual. New > > quirk should be introduced for this. > > Thanks for checking this. A10 and A20 use a separate driver (sun4i-dma). That > driver will also benefit from setting the max segment size, so I will send a > patch for it. > > I think all of the variants supported by sun6i-dma have the same segment size > capability, so no quirk is needed here. Ah, yes. Then this patch is: Reviewed-by: Jernej Skrabec <jernej.skrabec@xxxxxxxxx> Best regards, Jernej > > Regards, > Samuel > > >> > >> Exposing the real segment size limit (instead of the 64k default) > >> reduces the number of SG list segments needed for a transaction. > >> > >> Signed-off-by: Samuel Holland <samuel@xxxxxxxxxxxx> > >> --- > >> Tested on A64, verified that the maximum ALSA PCM period increased, and > >> that audio playback still worked. > >> > >> drivers/dma/sun6i-dma.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c > >> index b7557f437936..1425f87d97b7 100644 > >> --- a/drivers/dma/sun6i-dma.c > >> +++ b/drivers/dma/sun6i-dma.c > >> @@ -9,6 +9,7 @@ > >> > >> #include <linux/clk.h> > >> #include <linux/delay.h> > >> +#include <linux/dma-mapping.h> > >> #include <linux/dmaengine.h> > >> #include <linux/dmapool.h> > >> #include <linux/interrupt.h> > >> @@ -1334,6 +1335,8 @@ static int sun6i_dma_probe(struct platform_device > > *pdev) > >> INIT_LIST_HEAD(&sdc->pending); > >> spin_lock_init(&sdc->lock); > >> > >> + dma_set_max_seg_size(&pdev->dev, DMA_BIT_MASK(25)); > >> + > >> dma_cap_set(DMA_PRIVATE, sdc->slave.cap_mask); > >> dma_cap_set(DMA_MEMCPY, sdc->slave.cap_mask); > >> dma_cap_set(DMA_SLAVE, sdc->slave.cap_mask); > >> -- > >> 2.35.1 > >> > >> > > > > > >
