Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1427904 > unrolled thread
| Started by | Vinod Koul <vinod.koul@intel.com> |
|---|---|
| First post | 2016-06-21 18:00 +0200 |
| Last post | 2016-06-21 19:30 +0200 |
| Articles | 2 — 2 participants |
Back to article view | Back to linux.kernel
This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by
below is the oldest one visible, not the original post.
Re: [PATCH 7/8] dmaengine: tegra20-apb-dma: Only calculate residue if txstate exists. Vinod Koul <vinod.koul@intel.com> - 2016-06-21 18:00 +0200
Re: [PATCH 7/8] dmaengine: tegra20-apb-dma: Only calculate residue if txstate exists. Jon Hunter <jonathanh@nvidia.com> - 2016-06-21 19:30 +0200
| From | Vinod Koul <vinod.koul@intel.com> |
|---|---|
| Date | 2016-06-21 18:00 +0200 |
| Subject | Re: [PATCH 7/8] dmaengine: tegra20-apb-dma: Only calculate residue if txstate exists. |
| Message-ID | <rMwfM-7MM-19@gated-at.bofh.it> |
On Wed, Jun 08, 2016 at 09:51:57AM +0100, Jon Hunter wrote:
> Hi Peter,
>
> On 07/06/16 18:38, Peter Griffin wrote:
> > There is no point calculating the residue if there is
> > no txstate to store the value.
> >
> > Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
> > ---
> > drivers/dma/tegra20-apb-dma.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> > index 01e316f..7f4af8c 100644
> > --- a/drivers/dma/tegra20-apb-dma.c
> > +++ b/drivers/dma/tegra20-apb-dma.c
> > @@ -814,7 +814,7 @@ static enum dma_status tegra_dma_tx_status(struct dma_chan *dc,
> > unsigned int residual;
> >
> > ret = dma_cookie_status(dc, cookie, txstate);
> > - if (ret == DMA_COMPLETE)
> > + if (ret == DMA_COMPLETE || !txstate)
> > return ret;
>
> Thanks for reporting this. I agree that we should not do this, however,
> looking at the code for Tegra, I am wondering if this could change the
> actual state that is returned. Looking at dma_cookie_status() it will
> call dma_async_is_complete() which will return either DMA_COMPLETE or
> DMA_IN_PROGRESS. It could be possible that the actual state for the
> DMA transfer in the tegra driver is DMA_ERROR, so I am wondering if we
> should do something like the following ...
This one is stopping code execution when residue is not valid. Do notice
that it check for DMA_COMPLETE OR txstate. In other cases, wit will return
'that' state when txstate is NULL.
I am going to apply this.
>
> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> index 01e316f73559..45edab7418d0 100644
> --- a/drivers/dma/tegra20-apb-dma.c
> +++ b/drivers/dma/tegra20-apb-dma.c
> @@ -822,13 +822,8 @@ static enum dma_status tegra_dma_tx_status(struct dma_chan *dc,
> /* Check on wait_ack desc status */
> list_for_each_entry(dma_desc, &tdc->free_dma_desc, node) {
> if (dma_desc->txd.cookie == cookie) {
> - residual = dma_desc->bytes_requested -
> - (dma_desc->bytes_transferred %
> - dma_desc->bytes_requested);
> - dma_set_residue(txstate, residual);
> ret = dma_desc->dma_status;
> - spin_unlock_irqrestore(&tdc->lock, flags);
> - return ret;
> + goto found;
> }
> }
>
> @@ -836,17 +831,23 @@ static enum dma_status tegra_dma_tx_status(struct dma_chan *dc,
> list_for_each_entry(sg_req, &tdc->pending_sg_req, node) {
> dma_desc = sg_req->dma_desc;
> if (dma_desc->txd.cookie == cookie) {
> - residual = dma_desc->bytes_requested -
> - (dma_desc->bytes_transferred %
> - dma_desc->bytes_requested);
> - dma_set_residue(txstate, residual);
> ret = dma_desc->dma_status;
> - spin_unlock_irqrestore(&tdc->lock, flags);
> - return ret;
> + goto found;
> }
> }
>
> - dev_dbg(tdc2dev(tdc), "cookie %d does not found\n", cookie);
> + dev_warn(tdc2dev(tdc), "cookie %d not found\n", cookie);
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + return ret;
> +
> +found:
> + if (txstate) {
> + residual = dma_desc->bytes_requested -
> + (dma_desc->bytes_transferred %
> + dma_desc->bytes_requested);
> + dma_set_residue(txstate, residual);
> + }
> +
I feel this optimizes stuff, which seems okay. Feel free to send as proper
patch.
> spin_unlock_irqrestore(&tdc->lock, flags);
> return ret;
> }
>
> Cheers
> Jon
>
> --
> nvpublic
--
~Vinod
[toc] | [next] | [standalone]
| From | Jon Hunter <jonathanh@nvidia.com> |
|---|---|
| Date | 2016-06-21 19:30 +0200 |
| Subject | Re: [PATCH 7/8] dmaengine: tegra20-apb-dma: Only calculate residue if txstate exists. |
| Message-ID | <rMxES-lN-19@gated-at.bofh.it> |
| In reply to | #1427904 |
On 21/06/16 17:01, Vinod Koul wrote: > On Wed, Jun 08, 2016 at 09:51:57AM +0100, Jon Hunter wrote: >> Hi Peter, >> >> On 07/06/16 18:38, Peter Griffin wrote: >>> There is no point calculating the residue if there is >>> no txstate to store the value. >>> >>> Signed-off-by: Peter Griffin <peter.griffin@linaro.org> >>> --- >>> drivers/dma/tegra20-apb-dma.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c >>> index 01e316f..7f4af8c 100644 >>> --- a/drivers/dma/tegra20-apb-dma.c >>> +++ b/drivers/dma/tegra20-apb-dma.c >>> @@ -814,7 +814,7 @@ static enum dma_status tegra_dma_tx_status(struct dma_chan *dc, >>> unsigned int residual; >>> >>> ret = dma_cookie_status(dc, cookie, txstate); >>> - if (ret == DMA_COMPLETE) >>> + if (ret == DMA_COMPLETE || !txstate) >>> return ret; >> >> Thanks for reporting this. I agree that we should not do this, however, >> looking at the code for Tegra, I am wondering if this could change the >> actual state that is returned. Looking at dma_cookie_status() it will >> call dma_async_is_complete() which will return either DMA_COMPLETE or >> DMA_IN_PROGRESS. It could be possible that the actual state for the >> DMA transfer in the tegra driver is DMA_ERROR, so I am wondering if we >> should do something like the following ... > > This one is stopping code execution when residue is not valid. Do notice > that it check for DMA_COMPLETE OR txstate. In other cases, wit will return > 'that' state when txstate is NULL. Sorry what do you mean by "this one"? My point is that if the status is not DMA_COMPLETE, then it is possible that it could be DMA_ERROR (for tegra that is). However, dma_cookie_status will only return DMA_IN_PROGRESS or DMA_COMPLETE and so if 'txstate' is NULL we will not see the DMA_ERROR status anymore and just think it is in progress when it is actually an error. I do agree that the driver is broken as we are not checking for !txstate, but this also changes the behaviour a bit. Cheers Jon -- nvpublic
[toc] | [prev] | [standalone]
Back to top | Article view | linux.kernel
csiph-web