On Fri, Feb 01, 2019 at 04:37:59PM +0300, Dmitry Osipenko wrote: > 01.02.2019 16:28, Thierry Reding пишет: > > From: Thierry Reding <treding@xxxxxxxxxx> > > > > The HOST1X_CHANNEL_DMAEND is an offset relative to the value written to > > the HOST1X_CHANNEL_DMASTART register, but it is currently treated as an > > absolute address. This can cause SMMU faults if the CDMA fetches past a > > pushbuffer's IOMMU mapping. > > > > Properly setting the DMAEND prevents the CDMA from fetching beyond that > > address and avoid such issues. This is currently not observed because a > > whole (almost) page of essentially scratch space absorbs any excessive > > prefetching by CDMA. However, changing the number of slots in the push > > buffer can trigger these SMMU faults. > > > > Signed-off-by: Thierry Reding <treding@xxxxxxxxxx> > > --- > > drivers/gpu/host1x/hw/cdma_hw.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/host1x/hw/cdma_hw.c b/drivers/gpu/host1x/hw/cdma_hw.c > > index 485aef5761af..a24c090ac96f 100644 > > --- a/drivers/gpu/host1x/hw/cdma_hw.c > > +++ b/drivers/gpu/host1x/hw/cdma_hw.c > > @@ -75,7 +75,7 @@ static void cdma_start(struct host1x_cdma *cdma) > > > > cdma->last_pos = cdma->push_buffer.pos; > > start = cdma->push_buffer.dma; > > - end = start + cdma->push_buffer.size + 4; > > + end = cdma->push_buffer.size + 4; > > > > host1x_ch_writel(ch, HOST1X_CHANNEL_DMACTRL_DMASTOP, > > HOST1X_CHANNEL_DMACTRL); > > @@ -126,7 +126,7 @@ static void cdma_timeout_restart(struct host1x_cdma *cdma, u32 getptr) > > HOST1X_CHANNEL_DMACTRL); > > > > start = cdma->push_buffer.dma; > > - end = start + cdma->push_buffer.size + 4; > > + end = cdma->push_buffer.size + 4; > > > > /* set base, end pointer (all of memory) */ > > host1x_ch_writel(ch, lower_32_bits(start), HOST1X_CHANNEL_DMASTART); > > > > This seems fixes problem that was added by a previous patch in this > series, "gpu: host1x: Support 40-bit addressing". What about to just > squash the patches? This actually fixes a bug that's always been there. This just happens to touch the same lines as an earlier patch as a result of some refactoring that the earlier patch did. Thierry
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