linux-kernel - Re: [PATCH] mmc: sdhci-brcmstb: Fix mmc timeout errors on S5 suspend

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Message-ID: <6ce58f44-050d-3716-791c-0e924b43d26a@freebox.fr>
Date:   Mon, 25 Jan 2021 12:42:55 +0100
From:   Nicolas Schichan <nschichan@...ebox.fr>
To:     Al Cooper <alcooperx@...il.com>, linux-kernel@...r.kernel.org
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-arm-kernel@...ts.infradead.org, linux-mmc@...r.kernel.org,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH] mmc: sdhci-brcmstb: Fix mmc timeout errors on S5 suspend

On 07/01/2021 23:15, Al Cooper wrote:
> Commit e7b5d63a82fe ("mmc: sdhci-brcmstb: Add shutdown callback")
> that added a shutdown callback to the diver, is causing "mmc timeout"
> errors on S5 suspend. The problem was that the "remove" was queuing
> additional MMC commands after the "shutdown" and these caused
> timeouts as the MMC queues were cleaned up for "remove". The
> shutdown callback will be changed to calling sdhci-pltfm_suspend
> which should get better power savings because the clocks will be
> shutdown.
> 
> Fixes: e7b5d63a82fe ("mmc: sdhci-brcmstb: Add shutdown callback")
> Signed-off-by: Al Cooper <alcooperx@...il.com>
> ---
>  drivers/mmc/host/sdhci-brcmstb.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-brcmstb.c b/drivers/mmc/host/sdhci-brcmstb.c
> index bbf3496f4495..f9780c65ebe9 100644
> --- a/drivers/mmc/host/sdhci-brcmstb.c
> +++ b/drivers/mmc/host/sdhci-brcmstb.c
> @@ -314,11 +314,7 @@ static int sdhci_brcmstb_probe(struct platform_device *pdev)
>  
>  static void sdhci_brcmstb_shutdown(struct platform_device *pdev)
>  {
> -	int ret;
> -
> -	ret = sdhci_pltfm_unregister(pdev);
> -	if (ret)
> -		dev_err(&pdev->dev, "failed to shutdown\n");
> +	sdhci_pltfm_suspend(&pdev->dev);
>  }
>  
>  MODULE_DEVICE_TABLE(of, sdhci_brcm_of_match);
> 

Good morning,

Unfortunately this patch will cause link failures when CONFIG_PM_SLEEP is not
set in the kernel config, as in sdhci-pltfm.c, the implementation of
sdhci_pltfm_suspend() is in between #ifdef CONFIG_PM_SLEEP:

/opt/toolchains/aarch64-musl-1.1.21-gcc-8.3.0-binutils-2.32-gdb-7.12.1-2/bin/aarch64-linux-musl-ld:
drivers/mmc/host/sdhci-brcmstb.o: in function `sdhci_brcmstb_shutdown':
sdhci-brcmstb.c:(.text+0x16c): undefined reference to `sdhci_pltfm_suspend'
sdhci-brcmstb.c:(.text+0x16c): relocation truncated to fit: R_AARCH64_CALL26
against undefined symbol `sdhci_pltfm_suspend'


I'm not sure if definiting sdhci_pltfm_suspend() empty stubs in sdhci-pltfm.h
when CONFIG_PM_SLEEP is not set would be prefered over adding #ifdef
CONFIG_PM_SLEEP in sdhci-brcmstb.c, but I can send a patch for either solution.

Regards,

-- 
Nicolas Schichan