Re: [PATCH v4 12/15] mmc: core: add new 1.8v flag for mmc

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2012/9/27 Ulf Hansson <ulf.hansson@xxxxxxxxxx>:
> On 27 September 2012 12:39, Kevin Liu <keyuan.liu@xxxxxxxxx> wrote:
>> Hi, Ulf
>>
>> 2012/9/27 Ulf Hansson <ulf.hansson@xxxxxxxxxx>:
>>> Hi Kevin,
>>>
>>> On 26 September 2012 13:38, Kevin Liu <keyuan.liu@xxxxxxxxx> wrote:
>>>> From: Kevin Liu <kliu5@xxxxxxxxxxx>
>>>>
>>>> Mmc does NOT have special sequence requirements for 1.8v
>>>> signal voltage setting compared to sd and sdio.
>>>> Add a new 1.8v flag for mmc so as to use the same
>>>> start_signal_voltage_switch interface.
>>>
>>> This problem is protocol issue and should not be solved in the host
>>> driver. We have more issues for signal_voltage switch as well.
>>>
>>> Please have a look at Johan Rudholms patches:
>>> [PATCH v2 1/2] mmc: core: Proper signal voltage switch
>>> [PATCH v2 2/2] mmc: core: Power cycle card on voltage switch fail
>>>
>> I agree that we should do more things in protocal driver.
>> But the real voltage switch work is still done in host driver. If we
>> keep only one voltage switch interface, then we need to add a flag to
>> distinguish sd/sdio or emmc. Or we should define two interfaces to
>> call different host functions to handle this.
>> Johan's patches can't solve my issue.
>
> I understand that your driver today take care of specific things for
> sd/sdio. The reason for that is because of the protocol layer is not
> doing the voltage switch properly.
> The idea with Johans patches is resolve all these issues. Thus the
> host driver will just be responsible for the actual voltage switch to
> happen. So in the end your voltage switch function in the host is
> supposed to be rather simple.
>
Ok, Johans new patch is reasonable so I will hold this patch.

> If you still think you need to handle sd/sdio/eMMC in a specific
> manner in your driver, there are always mmc_card_sdio|sd|mmc functions
> you can use.
>
voltage_switch sometimes is called very early even before card type init.

Thanks
Kevin
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