Re: [PATCH] mmc: dw_mmc: Disable SDIO interrupts while suspended to fix suspend/resume

[Shawn Lin]

On 2019/4/22 23:21, Doug Anderson wrote:
> Hi,
>
> On Wed, Apr 10, 2019 at 3:13 PM Douglas Anderson <dianders@xxxxxxxxxxxx> wrote:
> > Processing SDIO interrupts while dw_mmc is suspended (or partly
> > suspended) seems like a bad idea.  We really don't want to be
> > processing them until we've gotten ourselves fully powered up.
> >
> > You might be wondering how it's even possible to become suspended when
> > an SDIO interrupt is active.  As can be seen in
> > dw_mci_enable_sdio_irq(), we explicitly keep dw_mmc out of runtime
> > suspend when the SDIO interrupt is enabled.  ...but even though we
> > stop normal runtime suspend transitions when SDIO interrupts are
> > enabled, the dw_mci_runtime_suspend() can still get called for a full
> > system suspend.
> >
> > Let's handle all this by explicitly masking SDIO interrupts in the
> > suspend call and unmasking them later in the resume call.  To do this
> > cleanly I'll keep track of whether the client requested that SDIO
> > interrupts be enabled so that we can reliably restore them regardless
> > of whether we're masking them for one reason or another.
> >
> > Without this fix it can be seen that rk3288-veyron Chromebooks with
> > Marvell WiFi would sometimes fail to resume WiFi even after picking my
> > recent mwifiex patch [1].  Specifically you'd see messages like this:
> >    mwifiex_sdio mmc1:0001:1: Firmware wakeup failed
> >    mwifiex_sdio mmc1:0001:1: PREP_CMD: FW in reset state
> >
> > ...and tracing through the resume code in the failing cases showed
> > that we were processing a SDIO interrupt really early in the resume
> > call.
> >
> > NOTE: downstream in Chrome OS 3.14 and 3.18 kernels (both of which
> > support the Marvell SDIO WiFi card) we had a patch ("CHROMIUM: sdio:
> > Defer SDIO interrupt handling until after resume") [2].  Presumably
> > this is the same problem that was solved by that patch.
> >
> > [1] https://lkml.kernel.org/r/20190404040106.40519-1-dianders@xxxxxxxxxxxx
> > [2] https://crrev.com/c/230765
> >
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> > ---
> > I didn't put any "Fixes" tag here, but presumably this could be
> > backported to whichever kernels folks found it useful for.  I have at
> > least confirmed that kernels v4.14 and v4.19 (as well as v5.1-rc2)
> > show the problem.  It is very easy to pick this to v4.19 and it
> > definitely fixes the problem there.
> >
> > I haven't spent the time to pick this to 4.14 myself, but presumably
> > it wouldn't be too hard to backport this as far as v4.13 since that
> > contains commit 32dba73772f8 ("mmc: dw_mmc: Convert to use
> > MMC_CAP2_SDIO_IRQ_NOTHREAD for SDIO IRQs").  Prior to that it might
> > make sense for anyone experiencing this problem to just pick the old
> > CHROMIUM patch to fix them.
> >
> >   drivers/mmc/host/dw_mmc.c | 24 ++++++++++++++++++++----
> >   drivers/mmc/host/dw_mmc.h |  3 +++
> >   2 files changed, 23 insertions(+), 4 deletions(-)
>
> Jaehoon / Shawn: any thoughts on this patch?

The intention seems reasonable to me, but just wonder if we need
mask/unmask SDIO interrupt when it's never used?  It's the same
situation for SDMMC_CLKEN_LOW_PWR that we couldn't stop providing
clock for SDIO cards, so I guess we need to check MMC_CAP_SDIO_IRQ
as well.

> -Doug