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. Best regards, Jernej > > 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 > >
