Re: [PATCH] mmc: core: add comment why sdio_reset is done at init time

[Chris Ball <cjb@laptop.org>]

Hi Philip,

On Sun, Feb 13, 2011 at 11:12:28PM -0800, Philip Rakity wrote:
> 
> sdio_reset sends a CMD52 to reset the sdio card.  This is
> highly recommended for sdio cards being reinitialized.  Since
> we do not know if the card is being reinitialized we just send
> the command.  SD/eMMC cards are supposed to ignore the CMD
> before the CMD0.  Document why we are doing this.
> 
> Signed-off-by: Philip Rakity <prakity@marvell.com>
> ---
>  drivers/mmc/core/core.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 34a7e8c..d9fb0d3 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1494,6 +1494,12 @@ static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
>  		mmc_hostname(host), __func__, host->f_init);
>  #endif
>  	mmc_power_up(host);
> +
> +	/*
> +	 * sdio_reset sends CMD52 to reset card.  Since we do not know
> +	 * if the card is being re-initialzed just send it.  CMD52
> +	 * should be ignored by SD/eMMC cards
> +	 */
>  	sdio_reset(host);
>  	mmc_go_idle(host);
>  

Thanks, pushed to mmc-next for .39.

-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child