On 12/02/2015 07:22 PM, Andy Gross wrote: > 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? OK I can rename BAM_MAX_DATA_SIZE to BAM_FIFO_SIZE, and use it when setting BAM_P_FIFO_SIZES register. Is that fine to you? -- regards, Stan -- 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
