Re: [PATCH v2] mmc: sdhci: fix incorrect command used in tuning

[Chris Ball <cjb@laptop.org>]

Hi Aaron,

On Mon, Nov 05 2012, Chris Ball wrote:
> On Tue, Jul 03 2012, Aaron Lu wrote:
>>  		 */
>>  		if ((host->flags & SDHCI_NEEDS_RETUNING) &&
>>  		    !(present_state & (SDHCI_DOING_WRITE | SDHCI_DOING_READ))) {
>> +			/* eMMC uses cmd21 while sd and sdio use cmd19 */
>> +			tuning_opcode = mmc->card->type == MMC_TYPE_MMC ?
>> +				MMC_SEND_TUNING_BLOCK_HS200 :
>> +				MMC_SEND_TUNING_BLOCK;
>
> This is causing a NULL deref crash here when run on host controllers
> with no card inserted -- mmc->card is NULL, as you'd expect, yet it's
> dereferenced anyway.  Maybe the system you tested it on only has an
> eMMC, so you never noticed that it crashes if there's no card present?
> Or maybe it's abnormal for host controllers to set SDHCI_NEEDS_RETUNING
> when there's no card present?

I'm going to send my fix to Linus (and hence stable@) tomorrow morning,
since it's important to remove this crash.  Let me know what you think
when you get a chance.

Thanks,

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