linux-kernel - Re: [PATCH] mmc: sdhci-acpi: Clear amd_sdhci

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Date:   Tue, 1 Sep 2020 15:19:30 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Raul E Rangel <rrangel@...omium.org>
Cc:     Nehal-bakulchandra.Shah@....com, chris.wang@....com,
        Akshu.Agrawal@....com, Ulf Hansson <ulf.hansson@...aro.org>,
        linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org
Subject: Re: [PATCH] mmc: sdhci-acpi: Clear amd_sdhci_host on reset

On 1/09/20 12:10 am, Raul E Rangel wrote:
> commit 61d7437ed1390 ("mmc: sdhci-acpi: Fix HS400 tuning for AMDI0040")
> broke resume for HS400. When the system suspends the eMMC controller is
> powered down. So on resume we need to reinitialize the controller.
> amd_sdhci_host was not getting cleared, so the DLL was never re-enabled
> on resume. This results in HS400 being non-functional.
> 
> This change clears the tuned_clock flag, clears the dll_enabled flag and
> disables the DLL on reset.
> 
> Fixes: 61d7437ed1390 ("mmc: sdhci-acpi: Fix HS400 tuning for AMDI0040")
> 
> Signed-off-by: Raul E Rangel <rrangel@...omium.org>

Acked-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
> - Performed 100+ suspend/resume cycles without issue.
> - Also verified tuning continues to work.
> 
>  drivers/mmc/host/sdhci-acpi.c | 31 ++++++++++++++++++++++++-------
>  1 file changed, 24 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
> index 962f074ca1742..284cba11e2795 100644
> --- a/drivers/mmc/host/sdhci-acpi.c
> +++ b/drivers/mmc/host/sdhci-acpi.c
> @@ -551,12 +551,18 @@ static int amd_select_drive_strength(struct mmc_card *card,
>  	return MMC_SET_DRIVER_TYPE_A;
>  }
>  
> -static void sdhci_acpi_amd_hs400_dll(struct sdhci_host *host)
> +static void sdhci_acpi_amd_hs400_dll(struct sdhci_host *host, bool enable)
>  {
> +	struct sdhci_acpi_host *acpi_host = sdhci_priv(host);
> +	struct amd_sdhci_host *amd_host = sdhci_acpi_priv(acpi_host);
> +
>  	/* AMD Platform requires dll setting */
>  	sdhci_writel(host, 0x40003210, SDHCI_AMD_RESET_DLL_REGISTER);
>  	usleep_range(10, 20);
> -	sdhci_writel(host, 0x40033210, SDHCI_AMD_RESET_DLL_REGISTER);
> +	if (enable)
> +		sdhci_writel(host, 0x40033210, SDHCI_AMD_RESET_DLL_REGISTER);
> +
> +	amd_host->dll_enabled = enable;
>  }
>  
>  /*
> @@ -596,10 +602,8 @@ static void amd_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>  
>  		/* DLL is only required for HS400 */
>  		if (host->timing == MMC_TIMING_MMC_HS400 &&
> -		    !amd_host->dll_enabled) {
> -			sdhci_acpi_amd_hs400_dll(host);
> -			amd_host->dll_enabled = true;
> -		}
> +		    !amd_host->dll_enabled)
> +			sdhci_acpi_amd_hs400_dll(host, true);
>  	}
>  }
>  
> @@ -620,10 +624,23 @@ static int amd_sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
>  	return err;
>  }
>  
> +static void amd_sdhci_reset(struct sdhci_host *host, u8 mask)
> +{
> +	struct sdhci_acpi_host *acpi_host = sdhci_priv(host);
> +	struct amd_sdhci_host *amd_host = sdhci_acpi_priv(acpi_host);
> +
> +	if (mask & SDHCI_RESET_ALL) {
> +		amd_host->tuned_clock = false;
> +		sdhci_acpi_amd_hs400_dll(host, false);
> +	}
> +
> +	sdhci_reset(host, mask);
> +}
> +
>  static const struct sdhci_ops sdhci_acpi_ops_amd = {
>  	.set_clock	= sdhci_set_clock,
>  	.set_bus_width	= sdhci_set_bus_width,
> -	.reset		= sdhci_reset,
> +	.reset		= amd_sdhci_reset,
>  	.set_uhs_signaling = sdhci_set_uhs_signaling,
>  };
>  
>