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

On Wed, Apr 10, 2019 at 3:13 PM Douglas Anderson <dianders@chromium.org> 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@chromium.org
> [2] https://crrev.com/c/230765
>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> 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?

-Doug

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