On Wed, Dec 02, 2015 at 06:44:11PM +0200, Stanimir Varbanov wrote: > On 12/01/2015 07:23 PM, Andy Gross wrote: > > On Tue, Dec 01, 2015 at 11:14:58AM +0200, Stanimir Varbanov wrote: > >> The pipe fifo size register must instruct the bam hw > >> how many hw descriptors can be pushed to fifo. Currently > >> we isntruct the hw with 32KBytes but wrap the tail in > >> bam_start_dma in BAM_P_EVNT_REG on 4095 i.e. 32760. This > >> leads to stalled transactions when the tail wraps. > >> > >> Fix this by use the correct fifo size in BAM_P_FIFO_SIZES > >> register i.e. 32K - 8. > >> > >> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@xxxxxxxxxx> > >> --- > >> drivers/dma/qcom_bam_dma.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/dma/qcom_bam_dma.c b/drivers/dma/qcom_bam_dma.c > >> index 0f06f3b7a72b..6d290de9ab2b 100644 > >> --- a/drivers/dma/qcom_bam_dma.c > >> +++ b/drivers/dma/qcom_bam_dma.c > >> @@ -458,7 +458,7 @@ static void bam_chan_init_hw(struct bam_chan *bchan, > >> */ > >> writel_relaxed(ALIGN(bchan->fifo_phys, sizeof(struct bam_desc_hw)), > >> bam_addr(bdev, bchan->id, BAM_P_DESC_FIFO_ADDR)); > >> - writel_relaxed(BAM_DESC_FIFO_SIZE, > >> + writel_relaxed(BAM_MAX_DATA_SIZE, > >> bam_addr(bdev, bchan->id, BAM_P_FIFO_SIZES)); > > > > This is just using the #define. That is ok, but if you use this instead of the > > BAM_P_FIFO_SIZES then you need to fix your comment. Or actually use the > > register value.... otherwise looks fine. > > I did not follow your comment, but the intension of the patch is to set > the proper FIFO size in BAM_P_FIFO_SIZES register, i.e. 32K - 8. Sorry, I mixed up the usage and was thinking there was something you read out that told you the size. That's not how it works, unfortunately. The MAX_DATA_SIZE is fine, but the name is a little misleading. Perhaps just BAM_FIFO_SIZE? Regards, Andy -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
