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

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

Hello.

On 09/18/2015 03:21 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.
>
> If the driver can be updated to do the right thing then that seems

    OK, I'll try going this way...

> preferable to me. If so would it be the case that the presence of the
> "disable-wp" property would not have any run-time effect?

    Yes.

MBR, Sergei