Re: [BUG] CMD52 sent as first command not CMD0

[Albert Herranz <albert_herranz@yahoo.es>]

Hi,

On 02/06/2011 02:35 AM, Philip Rakity wrote:
> 
> proposed solution:  I cannot verify this fix until Monday.
> =====
> 
> CMD52 is a reset for SDIO cards.  CMD0 is not sufficient when
> the card is being re-initialized.  Only send CMD52 if
> a) doing a reinitialize
> b) card is SDIO or SDIO_COMBO
> 
> Signed-off-by: Philip Rakity <prakity@marvell.com>
> ---
>  drivers/mmc/core/core.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 30d4da4..f0ce6f6 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1521,7 +1521,12 @@ 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(host);
> +
> +	/* reset sdio before CMD0 when card is being reinitialized */
> +	if (host->card &&
> +		(host->card->type == MMC_TYPE_SDIO ||
> +		host->card->type == MMC_TYPE_SD_COMBO))
> +			sdio_reset(host);
>  	mmc_go_idle(host);
>  	mmc_hwungate_clock(host);
>  

At least on the Nintendo Wii, a platform reset _does not_ reset the SDIO hardware, and there is no known way to power-off/power-on it.
So, in some cases like after a system reboot, we need to issue a CMD52 before a CMD0 (even if on that particular case host->card is NULL) to properly reset the Nintendo Wii SDIO-based Wireless LAN card from its previous state, otherwise the card is not detected.

The proposed fix breaks this and makes the card unavailable after a system reboot.

If you are concerned about unconditionally issuing a CMD52 then we can use a quirk to make sure that we always perform a SDIO reset at least for the Nintendo Wii.

Cheers,
Albert