[RFC] How working MMC_BUS_WIDTH_TEST??

[RFC] How working MMC_BUS_WIDTH_TEST??

[Jaehoon Chung]

Hi..

I found the MMC_CAP_BUS_WIDTH_TEST...
In mailing, I read the related patches..
but i didn't fully understand...

/*
 * If controller can't handle bus width test,
 * compare ext_csd previously read in 1 bit mode
 * against ext_csd at new bus width
 */
if (!(host->caps & MMC_CAP_BUS_WIDTH_TEST))
	err = mmc_compare_ext_csds(card,
		ext_csd,
		bus_width);
else
	err = mmc_bus_test(card, bus_width);
if (!err)
	break;

And i tested suspend/resume..it's failed..
If i didn't set MMC_CAP_BUS_WIDTH_TEST, always return -EINVAL..
(using SDHCI controller, card is eMMC4.41)

Didn't compare ext_csd's value..

So i want to know how use MMC_CAP_BUS_WIDTH_TEST..

Thanks,
Jaehoon Chung

Re: [RFC] How working MMC_BUS_WIDTH_TEST??

[Philip Rakity]

On Jun 28, 2011, at 3:54 AM, Jaehoon Chung wrote:

> Hi..
> 
> I found the MMC_CAP_BUS_WIDTH_TEST...
> In mailing, I read the related patches..
> but i didn't fully understand...
> 
> /*
> * If controller can't handle bus width test,
> * compare ext_csd previously read in 1 bit mode
> * against ext_csd at new bus width
> */
> if (!(host->caps & MMC_CAP_BUS_WIDTH_TEST))
> 	err = mmc_compare_ext_csds(card,
> 		ext_csd,
> 		bus_width);
> else
> 	err = mmc_bus_test(card, bus_width);
> if (!err)
> 	break;
> 
> And i tested suspend/resume..it's failed..
> If i didn't set MMC_CAP_BUS_WIDTH_TEST, always return -EINVAL..
> (using SDHCI controller, card is eMMC4.41)
> 
> Didn't compare ext_csd's value..
> 
> So i want to know how use MMC_CAP_BUS_WIDTH_TEST..

I am using eMMC and code works fine so  maybe there is issue in no ext_csd.  You will need to
add debug code to the compare_ext_csd and see what is not right and we can adjust the code.
I am surprised that resume fails -- code will default to 1 bit data and it is NOT possible for this to
be wrong.  At the moment -- clueless to explain with more information.

TheCMD14/ CMD19 is in JEDEC spec for bus width testing.  Sends a pattern to the card and
based on the returned values detects the bus width.  Some controllers do NOT support this command.
The just do not work.  You need to figure this out by enabling the quirk.  No other way to know.

regards,

Philip

> 
> Thanks,
> Jaehoon Chung

Re: [RFC] How working MMC_BUS_WIDTH_TEST??

[Jaehoon Chung]

Philip Rakity wrote:
> On Jun 28, 2011, at 3:54 AM, Jaehoon Chung wrote:
> 
>> Hi..
>>
>> I found the MMC_CAP_BUS_WIDTH_TEST...
>> In mailing, I read the related patches..
>> but i didn't fully understand...
>>
>> /*
>> * If controller can't handle bus width test,
>> * compare ext_csd previously read in 1 bit mode
>> * against ext_csd at new bus width
>> */
>> if (!(host->caps & MMC_CAP_BUS_WIDTH_TEST))
>> 	err = mmc_compare_ext_csds(card,
>> 		ext_csd,
>> 		bus_width);
>> else
>> 	err = mmc_bus_test(card, bus_width);
>> if (!err)
>> 	break;
>>
>> And i tested suspend/resume..it's failed..
>> If i didn't set MMC_CAP_BUS_WIDTH_TEST, always return -EINVAL..
>> (using SDHCI controller, card is eMMC4.41)
>>
>> Didn't compare ext_csd's value..
>>
>> So i want to know how use MMC_CAP_BUS_WIDTH_TEST..
> 
> I am using eMMC and code works fine so  maybe there is issue in no ext_csd.  You will need to
> add debug code to the compare_ext_csd and see what is not right and we can adjust the code.
> I am surprised that resume fails -- code will default to 1 bit data and it is NOT possible for this to
> be wrong.  At the moment -- clueless to explain with more information.
> 
> TheCMD14/ CMD19 is in JEDEC spec for bus width testing.  Sends a pattern to the card and
> based on the returned values detects the bus width.  Some controllers do NOT support this command.
> The just do not work.  You need to figure this out by enabling the quirk.  No other way to know.

When card is probing, i think that need to test bus-width.
If card is non-removable, unnecessary bus_width test during resuming.
Because already know that support n-bit bus-width..how about this?

> 
> regards,
> 
> Philip
> 
>> Thanks,
>> Jaehoon Chung
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: [RFC] How working MMC_BUS_WIDTH_TEST??

[Philip Rakity]

On Jun 28, 2011, at 9:42 PM, Jaehoon Chung wrote:

> Philip Rakity wrote:
>> On Jun 28, 2011, at 3:54 AM, Jaehoon Chung wrote:
>> 
>>> Hi..
>>> 
>>> I found the MMC_CAP_BUS_WIDTH_TEST...
>>> In mailing, I read the related patches..
>>> but i didn't fully understand...
>>> 
>>> /*
>>> * If controller can't handle bus width test,
>>> * compare ext_csd previously read in 1 bit mode
>>> * against ext_csd at new bus width
>>> */
>>> if (!(host->caps & MMC_CAP_BUS_WIDTH_TEST))
>>> 	err = mmc_compare_ext_csds(card,
>>> 		ext_csd,
>>> 		bus_width);
>>> else
>>> 	err = mmc_bus_test(card, bus_width);
>>> if (!err)
>>> 	break;
>>> 
>>> And i tested suspend/resume..it's failed..
>>> If i didn't set MMC_CAP_BUS_WIDTH_TEST, always return -EINVAL..
>>> (using SDHCI controller, card is eMMC4.41)
>>> 
>>> Didn't compare ext_csd's value..
>>> 
>>> So i want to know how use MMC_CAP_BUS_WIDTH_TEST..
>> 
>> I am using eMMC and code works fine so  maybe there is issue in no ext_csd.  You will need to
>> add debug code to the compare_ext_csd and see what is not right and we can adjust the code.
>> I am surprised that resume fails -- code will default to 1 bit data and it is NOT possible for this to
>> be wrong.  At the moment -- clueless to explain with more information.
>> 
>> TheCMD14/ CMD19 is in JEDEC spec for bus width testing.  Sends a pattern to the card and
>> based on the returned values detects the bus width.  Some controllers do NOT support this command.
>> The just do not work.  You need to figure this out by enabling the quirk.  No other way to know.
> 
> When card is probing, i think that need to test bus-width.
> If card is non-removable, unnecessary bus_width test during resuming.

agree not necessary but does not explain error.


> Because already know that support n-bit bus-width..how about this?
> 
>> 
>> regards,
>> 
>> Philip
>> 
>>> Thanks,
>>> Jaehoon Chung
>> 
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> 
> 

Re: [RFC] How working MMC_BUS_WIDTH_TEST??

[Jaehoon Chung]

Hi Philip..

If i didn't set MMC_CAP_BUS_WIDTH_TEST,
entered mmc_compare_ext_csds(). right?

i understand that mmc_compare_ext_csds() compared with previously ext_csd.
But in source code, always previously ext_csd is NULL.

I didn't find where assigned ext_csd..

I think that need to assign ext_csd..

If my point is right, i will send the patch..

Thanks
Jaehoon Chung

Philip Rakity wrote:
> On Jun 28, 2011, at 9:42 PM, Jaehoon Chung wrote:
> 
>> Philip Rakity wrote:
>>> On Jun 28, 2011, at 3:54 AM, Jaehoon Chung wrote:
>>>
>>>> Hi..
>>>>
>>>> I found the MMC_CAP_BUS_WIDTH_TEST...
>>>> In mailing, I read the related patches..
>>>> but i didn't fully understand...
>>>>
>>>> /*
>>>> * If controller can't handle bus width test,
>>>> * compare ext_csd previously read in 1 bit mode
>>>> * against ext_csd at new bus width
>>>> */
>>>> if (!(host->caps & MMC_CAP_BUS_WIDTH_TEST))
>>>> 	err = mmc_compare_ext_csds(card,
>>>> 		ext_csd,
>>>> 		bus_width);
>>>> else
>>>> 	err = mmc_bus_test(card, bus_width);
>>>> if (!err)
>>>> 	break;
>>>>
>>>> And i tested suspend/resume..it's failed..
>>>> If i didn't set MMC_CAP_BUS_WIDTH_TEST, always return -EINVAL..
>>>> (using SDHCI controller, card is eMMC4.41)
>>>>
>>>> Didn't compare ext_csd's value..
>>>>
>>>> So i want to know how use MMC_CAP_BUS_WIDTH_TEST..
>>> I am using eMMC and code works fine so  maybe there is issue in no ext_csd.  You will need to
>>> add debug code to the compare_ext_csd and see what is not right and we can adjust the code.
>>> I am surprised that resume fails -- code will default to 1 bit data and it is NOT possible for this to
>>> be wrong.  At the moment -- clueless to explain with more information.
>>>
>>> TheCMD14/ CMD19 is in JEDEC spec for bus width testing.  Sends a pattern to the card and
>>> based on the returned values detects the bus width.  Some controllers do NOT support this command.
>>> The just do not work.  You need to figure this out by enabling the quirk.  No other way to know.
>> When card is probing, i think that need to test bus-width.
>> If card is non-removable, unnecessary bus_width test during resuming.
> 
> agree not necessary but does not explain error.
> 
> 
>> Because already know that support n-bit bus-width..how about this?
>>
>>> regards,
>>>
>>> Philip
>>>
>>>> Thanks,
>>>> Jaehoon Chung
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
>>> the body of a message to majordomo@vger.kernel.org
>>> 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@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>