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

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Message-ID: <CAPDyKFqObiC2fwZJ_0JArbVhnFZHV6bA0XJg0diwPgmRx1Bntg@mail.gmail.com>
Date:   Mon, 14 Mar 2022 12:17:49 +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 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

> The flag can still be enabled through DT property: keep-power-in-suspend.
>
> Signed-off-by: Yann Gautier <yann.gautier@...s.st.com>
> ---
> Resend the patch alone. It was previoulsy in a series [1] for which the
> other patches will be reworked.
>
> [1] https://lore.kernel.org/lkml/20220304135134.47827-1-yann.gautier@foss.st.com/
>
>  drivers/mmc/host/mmci.c | 5 ++++-
>  drivers/mmc/host/mmci.h | 1 +
>  2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> index 45b8608c935c..0e2f2f5d6a52 100644
> --- a/drivers/mmc/host/mmci.c
> +++ b/drivers/mmc/host/mmci.c
> @@ -274,6 +274,7 @@ static struct variant_data variant_stm32_sdmmc = {
>         .busy_detect            = true,
>         .busy_detect_flag       = MCI_STM32_BUSYD0,
>         .busy_detect_mask       = MCI_STM32_BUSYD0ENDMASK,
> +       .disable_keep_power     = true,
>         .init                   = sdmmc_variant_init,
>  };
>
> @@ -301,6 +302,7 @@ static struct variant_data variant_stm32_sdmmcv2 = {
>         .busy_detect            = true,
>         .busy_detect_flag       = MCI_STM32_BUSYD0,
>         .busy_detect_mask       = MCI_STM32_BUSYD0ENDMASK,
> +       .disable_keep_power     = true,
>         .init                   = sdmmc_variant_init,
>  };
>
> @@ -2172,7 +2174,8 @@ static int mmci_probe(struct amba_device *dev,
>         host->stop_abort.flags = MMC_RSP_R1B | MMC_CMD_AC;
>
>         /* We support these PM capabilities. */
> -       mmc->pm_caps |= MMC_PM_KEEP_POWER;
> +       if (!variant->disable_keep_power)
> +               mmc->pm_caps |= MMC_PM_KEEP_POWER;
>
>         /*
>          * We can do SGIO
> diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
> index e1a9b96a3396..2cad1ef9766a 100644
> --- a/drivers/mmc/host/mmci.h
> +++ b/drivers/mmc/host/mmci.h
> @@ -361,6 +361,7 @@ struct variant_data {
>         u32                     opendrain;
>         u8                      dma_lli:1;
>         u32                     stm32_idmabsize_mask;
> +       u8                      disable_keep_power:1;
>         void (*init)(struct mmci_host *host);
>  };
>
> --
> 2.25.1
>