linux-kernel - Re: [PATCH v2] mmc: sdhci: add quirk for ACMD23 broken

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Date:	Wed, 17 Dec 2014 19:48:59 +0000
From:	Chris Ball <chris@...ntf.net>
To:	Scott Branden <sbranden@...adcom.com>
Cc:	Ulf Hansson <ulf.hansson@...aro.org>, <linux-mmc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Ray Jui <rjui@...adcom.com>,
	<bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH v2] mmc: sdhci: add quirk for ACMD23 broken

Hi Scott, sorry for the delay,

On Fri, Dec 05 2014, Scott Branden wrote:
> Add quirk to handle broken auto-CMD23.
> Some controllers do not respond after the first auto-CMD23 is issued.
>
> This allows CMD23 to still work (mandatory for the faster UHS-I mode)
> rather than disabling CMD23 entirely via SDHCI_QUIRK2_HOST_NO_CMD23.
>
> Signed-off by: Corneliu Doban <cdoban@...adcom.com>
> Signed-off-by: Scott Branden <sbranden@...adcom.com>
> ---
>  drivers/mmc/host/sdhci.c  | 3 ++-
>  include/linux/mmc/sdhci.h | 2 ++
>  2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index ada1a3e..b37331f 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2985,7 +2985,8 @@ int sdhci_add_host(struct sdhci_host *host)
>  	/* Auto-CMD23 stuff only works in ADMA or PIO. */
>  	if ((host->version >= SDHCI_SPEC_300) &&
>  	    ((host->flags & SDHCI_USE_ADMA) ||
> -	     !(host->flags & SDHCI_USE_SDMA))) {
> +	     !(host->flags & SDHCI_USE_SDMA)) &&
> +	     !(host->quirks2 & SDHCI_QUIRK2_ACMD23_BROKEN)) {
>  		host->flags |= SDHCI_AUTO_CMD23;
>  		DBG("%s: Auto-CMD23 available\n", mmc_hostname(mmc));
>  	} else {
> diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
> index dba793e..d979cf9 100644
> --- a/include/linux/mmc/sdhci.h
> +++ b/include/linux/mmc/sdhci.h
> @@ -100,6 +100,8 @@ struct sdhci_host {
>  #define SDHCI_QUIRK2_BROKEN_DDR50			(1<<7)
>  /* Stop command (CMD12) can set Transfer Complete when not using MMC_RSP_BUSY */
>  #define SDHCI_QUIRK2_STOP_WITH_TC			(1<<8)
> +/* Controller broken with using ACMD23 */
> +#define SDHCI_QUIRK2_ACMD23_BROKEN			(1<<9)
>  
>  	int irq;		/* Device IRQ */
>  	void __iomem *ioaddr;	/* Mapped address */

This patch doesn't apply the quirk to any chipsets, so the patch
doesn't actually change any behavior when run on a mainline kernel.
Do you have a patch to apply the quirk to your chipset too?  We don't
typically accept patches that "don't do anything" for mainline users,
so that's why we'd like to see the chipset patch too.

Thanks,

- Chris.
-- 
Chris Ball   <http://printf.net/>
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