> -----Original Message----- > From: Ira W. Snyder [mailto:iws@xxxxxxxxxxxxxxxx] > Sent: Friday, October 16, 2009 9:04 PM > To: Dan Williams > Cc: Suresh Vishnu-B05022; herbert@xxxxxxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; linux-raid@xxxxxxxxxxxxxxx; > linuxppc-dev@xxxxxxxxxx; linux-crypto@xxxxxxxxxxxxxxx; Tabi > Timur-B04825 > Subject: Re: [PATCH v0 1/2] DMA: fsldma: Disable > DMA_INTERRUPT when Async_tx enabled > > On Thu, Oct 15, 2009 at 06:25:14PM -0700, Dan Williams wrote: > > [ added Leo and Timur to the Cc ] > > > > On Wed, Oct 14, 2009 at 11:41 PM, Vishnu Suresh > <Vishnu@xxxxxxxxxxxxx> wrote: > > > This patch disables the use of DMA_INTERRUPT capability with > > > Async_tx > > > > > > The fsldma produces a null transfer with DMA_INTERRUPT capability > > > when used with Async_tx. When RAID devices queue a > transaction via > > > Async_tx, this results in a hang. > > > > > > Signed-off-by: Vishnu Suresh <Vishnu@xxxxxxxxxxxxx> > > > --- > > > drivers/dma/fsldma.c | 6 ++++++ > > > 1 files changed, 6 insertions(+), 0 deletions(-) > > > > > > diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c index > > > 296f9e7..66d9b39 100644 > > > --- a/drivers/dma/fsldma.c > > > +++ b/drivers/dma/fsldma.c > > > @@ -1200,7 +1200,13 @@ static int __devinit > of_fsl_dma_probe(struct > > > of_device *dev, > > > - > fdev->reg.start + > > > 1); > > > > > > dma_cap_set(DMA_MEMCPY, fdev->common.cap_mask); > > > +#ifndef CONFIG_ASYNC_CORE > > > + /* > > > + * The DMA_INTERRUPT async_tx is a NULL transfer, > which will > > > + * triger a PE interrupt. > > > + */ > > > dma_cap_set(DMA_INTERRUPT, fdev->common.cap_mask); > > > +#endif > > > dma_cap_set(DMA_SLAVE, fdev->common.cap_mask); > > > fdev->common.device_alloc_chan_resources = > > > fsl_dma_alloc_chan_resources; > > > fdev->common.device_free_chan_resources = > > > fsl_dma_free_chan_resources; > > > > You are basically saying that fsl_dma_prep_interrupt() is > buggy. Can > > that routine be fixed rather than this piecemeal solution? If it > > cannot be fixed (i.e. hardware issue) then fsl_dma_prep_interrupt() > > should just be disabled/deleted altogether. We are working to fix this issue. > > > > For what it's worth, I've used the following code in the > recent past, without any issues. This was on an 83xx, within > the last few kernel releases. I haven't tried it on the latest -rc. This works fine as long as only DMA_MEMCPY is being used. The async_tx_channel_switch does not occur and the device_prep_dma_interrupt is not called. However, when a DMA_XOR capable device is exposed, which is differnet from the DMA_MEMCPY/INTERRUPT device, this path is hit. Is it proper to schedule a dma_interrupt from the channel switch call, even when the depend_tx and tx channels correspond to different devices? > > Using device_prep_dma_memcpy() can trigger a callback as > well, so the interrupt feature isn't strictly needed. Just > attach the callback to the last memcpy operation. > > static dma_cookie_t dma_async_interrupt(struct dma_chan *chan, > dma_async_tx_callback > callback, > void *data) { > struct dma_device *dev = chan->device; > struct dma_async_tx_descriptor *tx; > > /* Set up the DMA */ > tx = dev->device_prep_dma_interrupt(chan, DMA_PREP_INTERRUPT); > if (!tx) > return -ENOMEM; > > tx->callback = callback; > tx->callback_param = data; > > return tx->tx_submit(tx); > } > > Ira > > -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
