Re: [RFC] mmc: meson-gx: use memcpy_to/fromio for dram-access-quirk

[Robin Murphy]

On 2021-06-09 15:55, Neil Armstrong wrote:
> Hi Robin,
>
> On 09/06/2021 16:45, Robin Murphy wrote:
> > On 2021-06-09 14:07, Neil Armstrong wrote:
> > > Hi,
> > >
> > > On 08/06/2021 17:50, Marek Szyprowski wrote:
> > > > Hi
> > > >
> > > > On 08.06.2021 17:33, Neil Armstrong wrote:
> > > > > It has been reported that usage of memcpy() to/from an iomem mapping is invalid,
> > > > > and and recent arm64 memcpy update [1] triggers a memory abort when dram-access-quirk
> > > > > is used on the G12A/G12B platforms.
> > > > >
> > > > > This adds a local sg_copy_to_buffer which makes usage of io versions of memcpy
> > > > > when dram-access-quirk is enabled.
> > > > >
> > > > > Fixes: acdc8e71d9bb ("mmc: meson-gx: add dram-access-quirk")
> > > > > Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> > > > > Suggested-by: Mark Rutland <mark.rutland@xxxxxxx>
> > > > > Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> > > > >
> > > > > [1] 285133040e6c ("arm64: Import latest memcpy()/memmove() implementation")
> > > > >
> > > > > Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> > > > > ---
> > > > > Hi Ulf, Marek, Mark,
> > > > >
> > > > > I haven't tested the patch yet, but should fix issue reported at [2].
> > > >
> > > > Works fine here and fixed the issue.
> > > >
> > > > Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> > >
> > > Thanks, I'll need to rework to pass an __iomem pointer to memcpy_to/fromio so sparse doesn't scream anymore.
> >
> > Hmm, might it be worth factoring out general sg_copy_{to,from}_iomem() helpers? From a quick grep I found at least mv_cesa_sg_copy() already doing essentially the same thing as meson_mmc_copy_buffer().
>
> It's definitely worth it, but since we need a quick fix, we should have meson_mmc_copy_buffer() as a fix then we should definitely move to sg_copy_{to,from}_iomem() helpers

Oh, that makes sense for sure - I was just doing some general thinking 
out loud before I forget about the whole thing :)

Cheers,
Robin.