Re: [PATCH] mmc: host: don't access at boot partition when mode is HS200/HS400.

[Jaehoon Chung <jh80.chung@samsung.com>]

Hi, Alex.

On 08/13/2014 10:27 PM, Alex Lemberg wrote:
> Hi,
> 
> HS200 & HS400 mode is not supported during boot operation, but I think this specific change 
> will prevent any boot operation or access to boot partition on all hosts with HS200 & HS400 capabilities in general,
> even in case then the eMMC card is DDR52 type.
Right, even if host capabilities is supported HS200 & HS400, card couldn't support them.
then maybe work the DDR50 or other mode.

> The actual bus clock speed need to be checked in order to prevent/allow boot operation, but not the host capabilities.

Exactly right. :)
As you mentioned, this patch is not perfect. but boot_part_access() called before set to final busmode.
I will consider it, but i think good that don't access at boot partition when mode is hs200/hs400 mode.

> 
> As for regular R/W access to boot partition, as far as I see from the JEDEC spec - it can work in HS200 & HS400 modes, so no change is required.

Well, it can work HS200 & HS400 mode at boot partition? i didn't think so.

> Please correct me if I wrong.

Thanks for comments.

Best Regards,
Jaehoon Chung

> 
> Thanks,
> Alex
> 
> 
> 
>> -----Original Message-----
>> From: linux-mmc-owner@vger.kernel.org [mailto:linux-mmc-
>> owner@vger.kernel.org] On Behalf Of Jaehoon Chung
>> Sent: Wednesday, August 13, 2014 7:46 AM
>> To: linux-mmc
>> Cc: Chris Ball; Ulf Hansson; Jaehoon Chung
>> Subject: [PATCH] mmc: host: don't access at boot partition when mode is
>> HS200/HS400.
>>
>> HS200/HS400 mode is not supported during boot operation.
>>
>> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
>> ---
>>  include/linux/mmc/host.h |    4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index
>> 7960424..ce5db96 100644
>> --- a/include/linux/mmc/host.h
>> +++ b/include/linux/mmc/host.h
>> @@ -445,6 +445,10 @@ static inline int mmc_host_cmd23(struct mmc_host
>> *host)
>>
>>  static inline int mmc_boot_partition_access(struct mmc_host *host)  {
>> +	/* HS200 & HS400 mode is not supported during boot operation */
>> +	if (host->caps2 & (MMC_CAP2_HS200 | MMC_CAP2_HS400))
>> +		return 0;
>> +
>>  	return !(host->caps2 & MMC_CAP2_BOOTPART_NOACC);  }
>>
>> --
>> 1.7.9.5
>>
>> --
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>