2011-03-24 06:02:39

by Viresh Kumar

Subject: [PATCH] dmaengine/dw_dmac fix: dwc_scan_descriptors must compare first desc address also with llp

dwc_scan_descriptors scans all descriptors from active_list in case transfer is
not completed. It compares first_desc->lli.llp, and then all childrens of its
tx_list. But it doesn't compare its own address, i.e. first_desc->txd.phys, as
this is what we have initially programmed into the controller register. So this
causes dma to stop and finish a transfer, which was never started. And thus
fail.

Signed-off-by: Viresh Kumar <[email protected]>
---
drivers/dma/dw_dmac.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index b95e6d3..1bd4803 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -304,6 +304,11 @@ static void dwc_scan_descriptors(struct dw_dma *dw, struct dw_dma_chan *dwc)
dev_vdbg(chan2dev(&dwc->chan), "scan_descriptors: llp=0x%x\n", llp);

list_for_each_entry_safe(desc, _desc, &dwc->active_list, desc_node) {
+ /* check first descriptors addr */
+ if (desc->txd.phys == llp)
+ return;
+
+ /* check first descriptors llp */
if (desc->lli.llp == llp)
/* This one is currently in progress */
return;
--
1.7.2.2

2011-03-31 06:14:43

by Vinod Koul

Subject: Re: [PATCH] dmaengine/dw_dmac fix: dwc_scan_descriptors must compare first desc address also with llp

On Thu, 2011-03-24 at 11:32 +0530, Viresh Kumar wrote:
> dwc_scan_descriptors scans all descriptors from active_list in case transfer is
> not completed. It compares first_desc->lli.llp, and then all childrens of its
> tx_list. But it doesn't compare its own address, i.e. first_desc->txd.phys, as
> this is what we have initially programmed into the controller register. So this
> causes dma to stop and finish a transfer, which was never started. And thus
> fail.
>
> Signed-off-by: Viresh Kumar <[email protected]>
> ---
> drivers/dma/dw_dmac.c | 5 +++++
> 1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
> index b95e6d3..1bd4803 100644
> --- a/drivers/dma/dw_dmac.c
> +++ b/drivers/dma/dw_dmac.c
> @@ -304,6 +304,11 @@ static void dwc_scan_descriptors(struct dw_dma *dw, struct dw_dma_chan *dwc)
> dev_vdbg(chan2dev(&dwc->chan), "scan_descriptors: llp=0x%x\n", llp);
>
> list_for_each_entry_safe(desc, _desc, &dwc->active_list, desc_node) {
> + /* check first descriptors addr */
> + if (desc->txd.phys == llp)
> + return;
> +
> + /* check first descriptors llp */
> if (desc->lli.llp == llp)
> /* This one is currently in progress */
> return;

Applied, Thanks

--
~Vinod