On Thu, Feb 24, 2022 at 05:30:09PM +0100, Miquel Raynal wrote: > andriy.shevchenko@xxxxxxxxxxxxxxx wrote on Wed, 23 Feb 2022 15:35:58 > +0200: > > On Tue, Feb 22, 2022 at 11:34:34AM +0100, Miquel Raynal wrote: ... > > It seems the logic in the ->terminate_all() is broken and we actually need > > to resume channel first (possibly conditionally, if it was suspended), then > > pause it and disable and resume again. > > > > The problem with ->terminate_all() is that it has no knowledge if it has > > been called on paused channel (that's why it has to pause channel itself). > > The pause on termination is required due to some issues in early steppings > > of iDMA 32-bit hardware implementations. > > > > If my theory is correct, the above change should fix the issues you see. > > I don't have access to these datasheets so I will believe your words > and try to apply Andy's solution. I ended up with the following fix, > hopefully I got it right: > > diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c > index 48cdefe997f1..59822664d8ec 100644 > --- a/drivers/dma/dw/core.c > +++ b/drivers/dma/dw/core.c > @@ -865,6 +865,10 @@ static int dwc_terminate_all(struct dma_chan *chan) > > clear_bit(DW_DMA_IS_SOFT_LLP, &dwc->flags); > > + /* Ensure the last byte(s) are drained before disabling the channel */ > + if (test_bit(DW_DMA_IS_PAUSED, &dwc->flags)) > + dwc_chan_resume(dwc, true); > + > dwc_chan_pause(dwc, true); > > dwc_chan_disable(dw, dwc); Yes, this is good enough PoC. Needs to be tested, thanks! > Phil, I know it's been 3 years since you investigated this issue, but > do you still have access to the script reproducing the issue? Even > better, do you still have the hardware to test? -- With Best Regards, Andy Shevchenko
