Re: [PATCH 5/6] mmc: sd: When resuming, try a little harder to init the card

[Arnd Bergmann <arnd@arndb.de>]

On Saturday 23 April 2011, John Stultz wrote:
> From: San Mehat <san@android.com>
> 
> CC: Chris Ball <cjb@laptop.org>
> CC: Arnd Bergmann <arnd@arndb.de>
> CC: Dima Zavin <dima@android.com>
> Signed-off-by: San Mehat <san@android.com>
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
>  drivers/mmc/core/sd.c |   19 +++++++++++++++++++
>  1 files changed, 19 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index c0f14cb..7b6cab2 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -734,12 +734,31 @@ static int mmc_sd_suspend(struct mmc_host *host)
>  static int mmc_sd_resume(struct mmc_host *host)
>  {
>  	int err;
> +#ifdef CONFIG_MMC_PARANOID_SD_INIT
> +	int retries;
> +#endif
>  
>  	BUG_ON(!host);
>  	BUG_ON(!host->card);
>  
>  	mmc_claim_host(host);
> +#ifdef CONFIG_MMC_PARANOID_SD_INIT
> +	retries = 5;
> +	while (retries) {
> +		err = mmc_sd_init_card(host, host->ocr, host->card);
> +
> +		if (err) {
> +			printk(KERN_ERR "%s: Re-init card rc = %d (retries = %d)\n",
> +			       mmc_hostname(host), err, retries);
> +			mdelay(5);
> +			retries--;
> +			continue;
> +		}
> +		break;
> +	}
> +#else
>  	err = mmc_sd_init_card(host, host->ocr, host->card);
> +#endif
>  	mmc_release_host(host);
>  

Again, the configuration option should not be there. Either it is needed for
some hardware or not.

The mdelay(5) is not ok, we must never spin in a kernel thread for that long.
Substituting it for msleep(5) solves that, but could still be considered
inappropriate during the boot process by some people -- a 25 ms delay for
each mmc host may be noticeable when people wait for the boot to complete.

It needs at least an explanation about why the delay is used here.

	Arnd