Re: [PATCH v2] ARM: shmobile: silk: add SDHI1 DT support

[Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>]

Hello.

On 09/02/2015 05:29 AM, Simon Horman wrote:

>>>>> Define the SILK board dependent part of the SDHI1 (connected to micro-SD slot)
>>>>> device nodes along with the necessary voltage regulators.
>>>>>
>>>>> Based on the original patch by Vladimir Barinov
>>>>> <vladimir.barinov@cogentembedded.com>.
>>>>>
>>>>> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
>>>>>
>>>>> ---
>>>>> This patch is against 'renesas-devel-20150810-v4.2-rc6' tag of Simon Horman's
>>>>> 'renesas.git' repo plus the R8A7794/SILK QSPI patches just re-posted. It needs
>>>>> the R8A7794 GPIO patches in order to compile.
>>>>>
>>>>> Changes in version 2:
>>>>> - removed not working SDHI0 stuff, renamed the patch;
>>>>> - replaced SDHI1's "wp-gpios" property with "disable-wp".
>>>>
>>>> I am wondering if you could explain the motivation for the "disable-wp"
>>>> update
>>>
>>>     Please see the comment in mmc_sd_get_ro().
>>>
>>>> and weather it is appropriate for other r8a779* dts files.
>>>
>>>     In case of micro-SD slots, yes.
>>
>>     The MMC binding document says it should only be specified if the
>> controller has WP detection logic. We, so far, seem to have been replying on
>> the GPIOs despite this logic is present (according to the R-Car gen2 SDHI
>> manuals I have). The driver will first call mmc_gpio_get_ro() and when that
>> fails due to "wp-gpios" not being specified, it proceeds to reading the
>> register but that is forbidden by TMIO_MMC_WRPROTECT_DISABLE flag set for
>> the R-Car gen1/2 chips, so 0 is always returned from tmio_mmc_get_ro().
>> There seems to be no point in going that far (and doing the runtime PM
>> dances) --

    Alternatively, the driver could be fixed to check the flag before the RPM 
call unlike what it does now.

>> and MMC_CAP2_NO_WRITE_PROTECT (set when "disable-wp" is specified) prohibits
>> doing that...
>
> That sounds reasonable to me.

    I'm still wondering why TMIO_MMC_WRPROTECT_DISABLE is set for the R-Car 
SoCs. Morimoto-san, any comments? Your change logs are too terse. :-)

> Some more questions from my side:

> * What is the status of this patch

    Tested, working.

> * Can you prepare patches for r8a779* dts files for micro-SD slots?

    Ugh, I probably can but won't promise anything.

MBR, Sergei