linux-kernel - Re: [PATCH RESEND] mmc: mmci: manage MMC_PM_KEEP

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Message-ID: <CAPDyKFr86QyN1sAaYR1WhfnNg2S6j2sr5dr=bn9L69r-QfXw7w@mail.gmail.com>
Date:   Mon, 14 Mar 2022 13:53:56 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Yann Gautier <yann.gautier@...s.st.com>
Cc:     linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        Christophe Kerello <christophe.kerello@...s.st.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Ludovic Barre <ludovic.barre@...s.st.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Russell King <linux@...linux.org.uk>,
        Marek Vasut <marex@...x.de>, kernel@...electronics.com,
        Manivannan Sadhasivam <mani@...nel.org>,
        Grzegorz Szymaszek <gszymaszek@...rt.pl>
Subject: Re: [PATCH RESEND] mmc: mmci: manage MMC_PM_KEEP_POWER per variant config

On Mon, 14 Mar 2022 at 13:20, Yann Gautier <yann.gautier@...s.st.com> wrote:
>
> On 3/14/22 12:17, Ulf Hansson wrote:
> > On Mon, 14 Mar 2022 at 10:53, Yann Gautier <yann.gautier@...s.st.com> wrote:
> >>
> >> Add a disable_keep_power field in variant_data struct. The
> >> MMC_PM_KEEP_POWER flag will be enabled if disable_keep_power is not set.
> >> It is only set to true for stm32_sdmmc variants.
> >>
> >> The issue was seen on STM32MP157C-DK2 board, which embeds a wifi chip.
> >> It doesn't correctly support low power, and we need to unbind the wifi
> >> driver before a suspend sequence. But the wifi chip firmware is then
> >> lost, and the communication with SDIO fails if MMC_PM_KEEP_POWER is
> >> enabled.
> >
> > So the platform supports to maintain the power for the embedded wifi
> > chip during system suspend, but the SDIO func driver (for the WiFi
> > chip) doesn't implement its part correctly. Did I get that right?
> >
> > In that case, it sounds to me like we should try to fix the support
> > for power management in the SDIO func driver instead, no?
> > I am happy to help with guidance/review if that is needed. What SDIO
> > func driver is this about?
> >
> > Kind regards
> > Uffe
> >
>
> Hi Ulf,
>
> I blindly pushed the patch without rechecking it.
> I rephrased it in our downstream to better explain the issue:
>
> The issue was seen on STM32MP157C-DK2 board, which embeds a wifi chip.
> It doesn't correctly support low power on this board. The Wifi chip
> awaits an always-on regulator, but it was connected to v3v3 which is off
> in low-power sequence. MMC_PM_KEEP_POWER should then be disabled.
>
> If it's OK for you, I'll resend the patch with the updated commit message.

Yes, that works fine for me!

[...]

Kind regards
Uffe