On September 21, 2018 12:42:20 PM PDT, Paul Burton <paul.burton@xxxxxxxx> wrote:
>Hi Christoph,
>
>On Fri, Sep 21, 2018 at 08:10:52AM +0200, Christoph Hellwig wrote:
>> Paul, other mips folks, any comments?
>>
>> At this point I'm tempted to just move it to 4.20 and add a stable
>> tag given that no one cared so far.
>
>Copying Kevin & Florian as maintainers of the affected BMIPS systems in
>case they have anything to add.
>
>> On Tue, Sep 11, 2018 at 11:00:49AM +0200, Christoph Hellwig wrote:
>> > The patch adding the infrastructure failed to actually add the
>symbol
>> > declaration, oops..
>> >
>> > Fixes: faef87723a ("dma-noncoherent: add a
>arch_sync_dma_for_cpu_all hook")
>> > Signed-off-by: Christoph Hellwig <hch@xxxxxx>
>> > ---
>> > kernel/dma/Kconfig | 3 +++
>> > 1 file changed, 3 insertions(+)
>> >
>> > diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
>> > index 9bd54304446f..1b1d63b3634b 100644
>> > --- a/kernel/dma/Kconfig
>> > +++ b/kernel/dma/Kconfig
>> > @@ -23,6 +23,9 @@ config ARCH_HAS_SYNC_DMA_FOR_CPU
>> > bool
>> > select NEED_DMA_MAP_STATE
>> >
>> > +config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL
>> > + bool
>> > +
>> > config DMA_DIRECT_OPS
>> > bool
>> > depends on HAS_DMA
>
>The change looks reasonable to me, so feel free to take your choice of:
>
> Reviewed-by: Paul Burton <paul.burton@xxxxxxxx>
> Acked-by: Paul Burton <paul.burton@xxxxxxxx>
>
>My thought would be that it would be ideal to fix in 4.19 since that's
>where the breakage is, but having said that I don't have much insight
>into how bad the breakage is for the affected systems.
AFAIR, DMA corruption is typically what you would observe, which could prove difficult if you are not exactly looking for it. In any case, I don't have a BMIPS system running 4.19 right now to exercise this on, but this looks correct:
Acked-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
--
Florian
