Hi
On Tue, Jun 1, 2010 at 6:51 PM, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
> Kyungmin Park wrote:
>>
>> The eMMC spec 4.4 and 4.3 + additional feature chips has CSD structure
>> version 3
>
> That is not exactly correct. There is no CSD structure version 1.3.
> Instead
> there are two fields for CSD structure version. One in CSD and one in
> Extended CSD.
>
> In CSD there is:
>
> CSD_STRUCTURE [127:126]
> Describes the version of the CSD structure.
> Table 44 — CSD register structure
> CSD_STRUCTURE CSD Structure Version Valid for System Specification
> Version
> 0 CSD version No. 1.0 Allocated by MMCA
> 1 CSD version No. 1.1 Allocated by MMCA
> 2 CSD version No. 1.2 Version 4.1–4.2–4.3
> 3 Version is coded in the CSD_STRUCTURE byte in the EXT_CSD
> register
>
> So the 3 does not mean version 1.3 it just means look at Extended CSD
> instead.
> But the Extended CSD field does not define CSD structure version 3 at all.
>
> CSD_STRUCTURE [194]
> This field is a continuation of the CSD_STRUCTURE field in the CSD register
> Table 78 — CSD register structure
> CSD_STRUCTURE CSD structure version Valid for System Specification
> Version
> 0 CSD version No. 1.0 Allocated by MMCA
> 1 CSD version No. 1.1 Allocated by MMCA
> 2 CSD version No. 1.2 Version 4.1–4.2–4.3-4.4
> 3–255 Reserved for future use
Thank you for Info. I got the eMMC v4.4 spec yesterday.
>
>> To probe these chip properly and make it simple.
>> it doesn't check CSD structure.
>>
>> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
>> ---
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index 89f7a25..9e42bc6 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -118,15 +118,12 @@ static int mmc_decode_csd(struct mmc_card *card)
>> u32 *resp = card->raw_csd;
>> /*
>> - * We only understand CSD structure v1.1 and v1.2.
>> + * We understand all CSD structure v1.1, v1.2 and v1.3.
>
> This comment is not correct. v1.3 does not exist.
I will fix it correctly.
>
>> * v1.2 has extra information in bits 15, 11 and 10.
>> */
>> csd_struct = UNSTUFF_BITS(resp, 126, 2);
>> - if (csd_struct != 1 && csd_struct != 2) {
>> - printk(KERN_ERR "%s: unrecognised CSD structure version
>> %d\n",
>
> I don't agree with removing this validation without a reason. Instead
> extend it to 3.
With above description. it has all meaning. even though we don't use
the '0' value.
Do you want to check if csd_struct == 0 case then fail?
>
> To support the '3' value properly, the Extended CSD CSD_STRUCTURE
> field needs to be validated also i.e. in mmc_read_ext_csd() do
> something like:
>
>
> u32 *resp = card->raw_csd;
>
> if (UNSTUFF_BITS(resp, 126, 2) == 3) {
> check ext_csd[194]
> }
I wonder are there any use case of csd version? it's just check
routine for proper operation.
basically no problem to display csd version and ext_csd version.
Thank you,
Kyungmin Park
>
>
>
>
>> + printk(KERN_DEBUG "%s: recognised CSD structure version %d\n",
>> mmc_hostname(card->host), csd_struct);
>> - return -EINVAL;
>> - }
>> csd->mmca_vsn = UNSTUFF_BITS(resp, 122, 4);
>> m = UNSTUFF_BITS(resp, 115, 4);
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
