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

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

[Viresh Kumar]

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 <viresh.kumar@st.com>
---
 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

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

[Koul, Vinod]

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 <viresh.kumar@st.com>
> ---
>  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