| Message ID | 5757DCAD.1090106@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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
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
On Tue, Jun 21, 2016 at 06:19:50PM +0100, Jon Hunter wrote: > > 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"? the patch > > 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). right it can be any state... and we check for only DMA_COMPLETE as residue has no meaning. > 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. Yes that is an existing issue, if you are reporting DMA_ERROR then you should add a check for DMA_ERROR as well and not do residue calculation for that case. > > I do agree that the driver is broken as we are not checking for > !txstate, but this also changes the behaviour a bit. It changes for better and not worse. Btw pls feel free to send a patch handling DMA_ERROR :)
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); + } + spin_unlock_irqrestore(&tdc->lock, flags); return ret; }