Re: [RFC] mmc: core: add the capability for broken voltage

[Adrian Hunter <adrian.hunter@intel.com>]

On 18/01/12 01:58, Kyungmin Park wrote:
> On 1/17/12, Adrian Hunter <adrian.hunter@intel.com> wrote:
>> On 17/01/12 11:53, Kyungmin Park wrote:
>>> On 1/17/12, Adrian Hunter <adrian.hunter@intel.com> wrote:
>>>> On 17/01/12 11:05, Kyungmin Park wrote:
>>>>> On 1/17/12, Adrian Hunter <adrian.hunter@intel.com> wrote:
>>>>>> On 16/01/12 10:49, Jaehoon Chung wrote:
>>>>>>> This patch is added the MMC_CAP2_BROKEN_VOLTAGE.
>>>>>>>
>>>>>>> if the voltage didn't satisfy between min_uV and max_uV,
>>>>>>
>>>>>> Why is the fixed voltage not in the acceptable range for the card?
>>>>>> Doesn't that risk breaking the card?
>>>>> Hi Adrian,
>>>>>
>>>>> I don't know, they uses the not supported voltage. but it's worked
>>>>> properly for long time.
>>>>
>>>> I wonder if there is a generic problem here that this fix hides.
>>>> It would be nice to have an explanation.  Do you know:
>>>> 	- what is the fixed voltage?
>>> Now 2.8V is supplied by gpio so make it fixed regulator
>>>> 	- is it supplying VCC or VCCQ?
>>> VDD in our schematic.
>>
>> Is it the NAND core voltage or the I/O voltage?
> In case of eMMC v4.41, it uses the same voltage, VDD is used for MMC
> I/O block and controller and another VDDF is used for flash.

It seems to me you just need to override the value of mmc->ocr_avail_mmc
calculated in sdhci_add_host() in sdhci.c to reflect the fact that the only
voltage available is 2.8V.

>>
>>>> 	- what is the contents of the OCR register?
>>> In sdhci_set_power(). it returns SDHCI_POWER_180, SDHCI_POWER_300, and
>>> SDHCI_POWER_330.
>>> In probe time, it return the SDHCI_POWER_330, and but fixed regulator
>>> returns the 2.8V so it calls regulator_set_voltage. and return -EINVAL
>>> since it's fixed regulator.
>>>
>>> Of course we can make workaround, set fixed regulator voltage as 3.3V.
>>> Even though actual voltage is 2.8V. so it's ambiguous.
>>>
>>> that's reason introduces the new quirk.
>>>
>>> Thank you,
>>> Kyungmin Park
>>>>
>>>>> Galaxy S2 also uses the same voltage as ours.
>>>>>
>>>>> I also think the modify the regulator framework to support voltage
>>>>> change at fixed regulator. but it's not good idea and doesn't match
>>>>> the regulator concept. so modify the sdhci codes to support our
>>>>> boards.
>>>>>
>>>>> Thank you,
>>>>> Kyungmin Park
>>>>>>
>>>>>>> try to change the voltage in core.c.
>>>>>>> When change the voltage, maybe use the regulator_set_voltage().
>>>>>>>
>>>>>>> In regulator_set_voltage(), check the below condition.
>>>>>>>
>>>>>>> 	/* sanity check */
>>>>>>> 	if (!rdev->desc->ops->set_voltage &&
>>>>>>> 	    !rdev->desc->ops->set_voltage_sel) {
>>>>>>> 		ret = -EINVAL;
>>>>>>> 		goto out;
>>>>>>> 	}
>>>>>>>
>>>>>>> If Some-board should use the fixed-regulator, always return -EINVAL.
>>>>>>> Then, eMMC didn't initialize always.
>>>>>>>
>>>>>>> So if use the fixed-regulator or etc, we need to add the
>>>>>>> MMC_CAP2_BROKEN_VOLTAGE.
>>>>>>>
>>>>>>> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
>>>>>>> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
>>>>>>> ---
>>>>>>>  drivers/mmc/core/core.c  |    4 ++++
>>>>>>>  include/linux/mmc/host.h |    1 +
>>>>>>>  2 files changed, 5 insertions(+), 0 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>>>>>>> index bec0bf2..6848789 100644
>>>>>>> --- a/drivers/mmc/core/core.c
>>>>>>> +++ b/drivers/mmc/core/core.c
>>>>>>> @@ -1121,6 +1121,10 @@ int mmc_regulator_set_ocr(struct mmc_host *mmc,
>>>>>>>  		 * might not allow this operation
>>>>>>>  		 */
>>>>>>>  		voltage = regulator_get_voltage(supply);
>>>>>>> +
>>>>>>> +		if (mmc->caps2 & MMC_CAP2_BROKEN_VOLTAGE)
>>>>>>> +			min_uV = max_uV = voltage;
>>>>>>> +
>>>>>>>  		if (voltage < 0)
>>>>>>>  			result = voltage;
>>>>>>>  		else if (voltage < min_uV || voltage > max_uV)
>>>>>>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>>>>>>> index dd13e05..5659aee 100644
>>>>>>> --- a/include/linux/mmc/host.h
>>>>>>> +++ b/include/linux/mmc/host.h
>>>>>>> @@ -257,6 +257,7 @@ struct mmc_host {
>>>>>>>  #define MMC_CAP2_HS200_1_2V_SDR	(1 << 6)        /* can support */
>>>>>>>  #define MMC_CAP2_HS200		(MMC_CAP2_HS200_1_8V_SDR | \
>>>>>>>  				 MMC_CAP2_HS200_1_2V_SDR)
>>>>>>> +#define MMC_CAP2_BROKEN_VOLTAGE	(1 << 7)	/* Use the broken voltage */
>>>>>>>
>>>>>>>  	mmc_pm_flag_t		pm_caps;	/* supported pm features */
>>>>>>>  	unsigned int        power_notify_type;
>>>>>>> --
>>>>>>> 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
>>>>>>
>>>>>
>>>>
>>>> --
>>>> 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
>>
>