linux-kernel - Re: [PATCH 2/3] mmc: sdhci_am654: Reset Command and Data line after tuning

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Message-ID: <1431a5a3-cc17-b03b-1f94-3e4290f3ce7d@intel.com>
Date:   Wed, 15 Jan 2020 15:12:21 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Faiz Abbas <faiz_abbas@...com>, linux-kernel@...r.kernel.org,
        linux-mmc@...r.kernel.org
Cc:     ulf.hansson@...aro.org
Subject: Re: [PATCH 2/3] mmc: sdhci_am654: Reset Command and Data line after
 tuning

On 8/01/20 4:33 pm, Faiz Abbas wrote:
> The tuning data is leftover in the buffer after tuning. This can cause
> issues in future data commands, especially with CQHCI. Reset the command
> and data lines after tuning to continue from a clean state.
> 
> Fixes: 41fd4caeb00b ("mmc: sdhci_am654: Add Initial Support for AM654 SDHCI driver")
> Cc: stable@...r.kernel.org
> Signed-off-by: Faiz Abbas <faiz_abbas@...com>

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

> ---
>  drivers/mmc/host/sdhci_am654.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
> index 2d38b1e12a7e..59c0c41b3739 100644
> --- a/drivers/mmc/host/sdhci_am654.c
> +++ b/drivers/mmc/host/sdhci_am654.c
> @@ -240,6 +240,22 @@ static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg)
>  	writeb(val, host->ioaddr + reg);
>  }
>  
> +static int sdhci_am654_execute_tuning(struct mmc_host *mmc, u32 opcode)
> +{
> +	struct sdhci_host *host = mmc_priv(mmc);
> +	int err = sdhci_execute_tuning(mmc, opcode);
> +
> +	if (err)
> +		return err;
> +	/*
> +	 * Tuning data remains in the buffer after tuning.
> +	 * Do a command and data reset to get rid of it
> +	 */
> +	sdhci_reset(host, SDHCI_RESET_CMD | SDHCI_RESET_DATA);
> +
> +	return 0;
> +}
> +
>  static struct sdhci_ops sdhci_am654_ops = {
>  	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
>  	.get_timeout_clock = sdhci_pltfm_clk_get_max_clock,
> @@ -546,6 +562,8 @@ static int sdhci_am654_probe(struct platform_device *pdev)
>  		goto pm_runtime_put;
>  	}
>  
> +	host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
> +
>  	ret = sdhci_am654_init(host);
>  	if (ret)
>  		goto pm_runtime_put;
>