linux-kernel - Re: [PATCH 1/2] mmc: core: Add a capability for disabling mmc cards

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Date:	Wed, 22 Aug 2012 13:35:13 +0900
From:	Jaehoon Chung <jh80.chung@...sung.com>
To:	Doug Anderson <dianders@...omium.org>
Cc:	linux-mmc@...r.kernel.org, Olof Johansson <olof@...om.net>,
	Alim Akhtar <alim.akhtar@...sung.com>,
	Thomas P Abraham <thomas.ab@...sung.com>,
	Chris Ball <cjb@...top.org>,
	Will Newton <will.newton@...tec.com>,
	Seungwon Jeon <tgih.jun@...sung.com>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	James Hogan <james.hogan@...tec.com>,
	linux-kernel@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 1/2] mmc: core: Add a capability for disabling mmc cards

Hi Doug,

I didn't know what purpose is.
Why need to add the MMC_CAP2_NO_MMC?
If card is SD or SDIO, mmc_attach_mmc(host) should not be entered.
Could you explain to me in more detail?

Best Regards,
Jaehoon Chung

On 08/22/2012 01:05 PM, Doug Anderson wrote:
> On some systems we need a way to disable MMC card support in a MMC/SD
> card slot.  Add support in the core SD/MMC code to support this.
> 
> Signed-off-by: Doug Anderson <dianders@...omium.org>
> Signed-off-by: Alim Akhtar <alim.akhtar@...sung.com>
> ---
>  drivers/mmc/core/core.c  |    2 +-
>  include/linux/mmc/host.h |    1 +
>  2 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 8ac5246..3214972 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1981,7 +1981,7 @@ static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
>  		return 0;
>  	if (!mmc_attach_sd(host))
>  		return 0;
> -	if (!mmc_attach_mmc(host))
> +	if (!(host->caps2 & MMC_CAP2_NO_MMC) && !mmc_attach_mmc(host))
>  		return 0;
>  
>  	mmc_power_off(host);
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index f578a71..f36370e 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -257,6 +257,7 @@ struct mmc_host {
>  #define MMC_CAP2_HC_ERASE_SZ	(1 << 9)	/* High-capacity erase size */
>  #define MMC_CAP2_CD_ACTIVE_HIGH	(1 << 10)	/* Card-detect signal active high */
>  #define MMC_CAP2_RO_ACTIVE_HIGH	(1 << 11)	/* Write-protect signal active high */
> +#define MMC_CAP2_NO_MMC		(1 << 12)	/* Only SD supported, not MMC */
>  
>  	mmc_pm_flag_t		pm_caps;	/* supported pm features */
>  	unsigned int        power_notify_type;
> 

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