Hi, On Thu, Oct 18, 2012 at 02:09:43PM +0300, Andy Shevchenko wrote: > On Thu, 2012-10-18 at 13:34 +0300, Felipe Balbi wrote: > > On Thu, Oct 18, 2012 at 11:15:31AM +0300, Andy Shevchenko wrote: > > > On Wed, 2012-10-17 at 16:53 +0300, Felipe Balbi wrote: > > > > On Wed, Oct 17, 2012 at 04:36:58PM +0300, Andy Shevchenko wrote: > > > > > On Wed, 2012-10-17 at 16:09 +0300, Felipe Balbi wrote: > > > > > > > > diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c > > > > > > > > @@ -492,10 +491,8 @@ static void dwc_handle_error(struct dw_dma > > > > > > > *dw, struct dw_dma_chan *dwc) > > > > > > > * controller flagged an error instead of scribbling over > > > > > > > * random memory locations. > > > > > > > */ > > > > > > > - dev_printk(KERN_CRIT, chan2dev(&dwc->chan), > > > > > > > - "Bad descriptor submitted for DMA!\n"); > > > > > > > - dev_printk(KERN_CRIT, chan2dev(&dwc->chan), > > > > > > > - " cookie: %d\n", bad_desc->txd.cookie); > > > > > > > + dev_crit(chan2dev(&dwc->chan), "Bad descriptor submitted for > > > > > > > DMA!\n"); > > > > > > > + dev_crit(chan2dev(&dwc->chan), " cookie: %d\n", > > > > > > > bad_desc->txd.cookie); > > > > > > > > > > > > now this is critical, indeed. I would suggest using dev_WARN_ONCE() > > > > > > so > > > > > > that it's noisy enough to catch the failing user. > > > > > To this and upper comment, there is an explanation why it's critical. > > > > > I > > > > > guess the WARN_ONCE is not good enough, for example if we have more > > > > > than > > > > > one user making such noise. > > > > > > > > then use dev_WARN() > > > I can't see how dev_WARN could be more useful here than the dev_crit. In > > > current message we have channel and cookie to link back to the user. > > > What does WARN add meaningful? > > > > a dump_stack() > > How could it be useful? The dwc_handle_error is called from a tasklet > that is called from scheduler asynchronously. The tasklet is queued in > interrupt handler.
even if it's not useful, it's a lot more verbose and more likely to get user's attention. If someone's passing broken DMA descriptor, it should be a really big fat warning so we can get user reports early enoough. Anyway, it's your call, I don't mind really. -- balbi
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