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From:   Arend Van Spriel <arend.vanspriel@broadcom.com>
To:     Doug Anderson <dianders@chromium.org>,
        Wright Feng <Wright.Feng@cypress.com>
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Date:   Tue, 04 Jun 2019 18:48:57 +0200
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Subject: Re: [PATCH 1/3] brcmfmac: re-enable command decode in sdio_aos for BRCM 4354
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On June 4, 2019 6:01:26 PM Doug Anderson <dianders@chromium.org> wrote:

> Hi,
>
> On Mon, Jun 3, 2019 at 8:20 PM Wright Feng <Wright.Feng@cypress.com> wrote:
>>
>> On 2019/5/29 上午 12:11, Arend Van Spriel wrote:
>> > On May 28, 2019 6:09:21 PM Arend Van Spriel
>> > <arend.vanspriel@broadcom.com> wrote:
>> >
>> >> On May 28, 2019 5:52:10 PM Doug Anderson <dianders@chromium.org> wrote:
>> >>
>> >>> Hi,
>> >>>
>> >>> On Tue, May 28, 2019 at 5:18 AM Kalle Valo <kvalo@codeaurora.org> wrote:
>> >>>>
>> >>>> Douglas Anderson <dianders@chromium.org> wrote:
>> >>>>
>> >>>> > In commit 29f6589140a1 ("brcmfmac: disable command decode in
>> >>>> > sdio_aos") we disabled something called "command decode in sdio_aos"
>> >>>> > for a whole bunch of Broadcom SDIO WiFi parts.
>> >>>> >
>> >>>> > After that patch landed I find that my kernel log on
>> >>>> > rk3288-veyron-minnie and rk3288-veyron-speedy is filled with:
>> >>>> >   brcmfmac: brcmf_sdio_bus_sleep: error while changing bus sleep
>> >>>> state -110
>> >>>> >
>> >>>> > This seems to happen every time the Broadcom WiFi transitions out of
>> >>>> > sleep mode.  Reverting the part of the commit that affects the
>> >>>> WiFi on
>> >>>> > my boards fixes the problem for me, so that's what this patch does.
>> >>>> >
>> >>>> > Note that, in general, the justification in the original commit
>> >>>> seemed
>> >>>> > a little weak.  It looked like someone was testing on a SD card
>> >>>> > controller that would sometimes die if there were CRC errors on the
>> >>>> > bus.  This used to happen back in early days of dw_mmc (the
>> >>>> controller
>> >>>> > on my boards), but we fixed it.  Disabling a feature on all boards
>> >>>> > just because one SD card controller is broken seems bad.  ...so
>> >>>> > instead of just this patch possibly the right thing to do is to fully
>> >>>> > revert the original commit.
>> >>>> >
>> Since the commit 29f6589140a1 ("brcmfmac: disable command decode in
>> sdio_aos") causes the regression on other SD card controller, it is
>> better to revert it as you mentioned.
>> Actually, without the commit, we hit MMC timeout(-110) and hanged
>> instead of CRC error in our test.
>
> Any chance I can convince you to provide some official tags like
> Reviewed-by or Tested-by on the revert?
>
>> Would you please share the analysis of
>> dw_mmc issue which you fixed? We'd like to compare whether we got the
>> same issue.
>
> I'm not sure there's any single magic commit I can point to.  When I
> started working on dw_mmc it was terrible at handling error cases and
> would often crash / hang / stop all future communication upon certain
> classes or efforts.  There were dozens of problems we've had to fix
> over the years.  These problems showed up when we started supporting
> HS200 / UHS since the tuning phase really stress the error handling of
> the host controller.
>
> I searched and by the time we were supporting Broadcom SDIO cards the
> error handling was already pretty good.  ...but if we hadn't already
> made the error handling more robust for UHS tuning then we would have
> definitely hit these types of problems.  The only problem I remember
> having to solve in dw_mmc that was unique to Broadcom was commit
> 0bdbd0e88cf6 ("mmc: dw_mmc: Don't start commands while busy").  Any
> chance that could be what you're hitting?

That is indeed an issue I recall resulting in -110 errors.

> What host controller are you having problems with?

Knowing that will be a good start.

Regards,
Arend