On 27.06.2014 17:10, Doug Anderson wrote:
> Tomasz and Vikas,
>
> On Fri, Jun 27, 2014 at 5:17 AM, Tomasz Figa <tomasz.figa@xxxxxxxxx> wrote:
>> Hi Doug,
>>
>> On 26.06.2014 17:25, Doug Anderson wrote:
>>> Tomasz,
>>>
>>> On Thu, Jun 26, 2014 at 2:52 AM, Tomasz Figa <t.figa@xxxxxxxxxxx> wrote:
>>>> Hi Vikas, Doug,
>>>>
>>>> On 26.06.2014 11:15, Vikas Sajjan wrote:
>>>>> From: Doug Anderson <dianders@xxxxxxxxxxxx>
>>>>>
>>>>> The mask-tpm-reset GPIO is used by the kernel to prevent the TPM from
>>>>> being reset across sleep/wake. If we don't set it to anything then
>>>>> the TPM will be reset. U-Boot will detect this as invalid
>>>>> and will reset the system on resume time. This GPIO can always be low
>>>>> and not hurt anything. It will get pulled back high again during a
>>>>> normal warm reset when it will default back to an input.
>>>>>
>>>>> To properly preserve the TPM state across suspend/resume and to make
>>>>> the chrome U-Boot happy, properly set the GPIO to mask the
>>>>> reset to the TPM.
>>>>>
>>>>> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
>>>>> Signed-off-by: Vikas Sajjan <vikas.sajjan@xxxxxxxxxxx>
>>>>> ---
>>>>> arch/arm/boot/dts/exynos5420-peach-pit.dts | 20 ++++++++++++++++++++
>>>>> 1 file changed, 20 insertions(+)
>>>>>
>>>>> diff --git a/arch/arm/boot/dts/exynos5420-peach-pit.dts b/arch/arm/boot/dts/exynos5420-peach-pit.dts
>>>>> index 7649982..8fd990a 100644
>>>>> --- a/arch/arm/boot/dts/exynos5420-peach-pit.dts
>>>>> +++ b/arch/arm/boot/dts/exynos5420-peach-pit.dts
>>>>> @@ -87,6 +87,18 @@
>>>>> pinctrl-0 = <&usb301_vbus_en>;
>>>>> enable-active-high;
>>>>> };
>>>>> +
>>>>> + /* We need GPX0_6 to be low at sleep time; just keep it low always */
>>>>> + mask_tpm_reset_regulator: mask-tpm-reset-regulator {
>>>>> + compatible = "regulator-fixed";
>>>>> + regulator-name = "mask-tpm-reset ";
>>>>> + gpio = <&gpx0 6 0>;
>>>>> + enable-active-low;
>>>>> + regulator-boot-on;
>>>>> + regulator-always-on;
>>>>> + pinctrl-names = "default";
>>>>> + pinctrl-0 = <&mask_tpm_reset>;
>>>>> + };
>>>>
>>>> I don't think this pin is supposed to be a real regulator. If I'm right,
>>>> you should just add a hog for it, if you don't have a proper driver to
>>>> handle it.
>>>
>>> Yes, I agree that it shouldn't really be a regulator, but there's not
>>> a whole lot of choice. The pin needs to actually be driven low, not
>>> just pulled low. Without your proposed patch (pinctrl: samsung: Allow
>>> pin value to be initialized using pinfunc) I don't think it's possible
>>> to actually drive a pin low with a hog. I could be wrong, though.
>>>
>>
>> Uhm, I was convinced that this patch was already in. So I think your use
>> case is definitely a good reason to get back to this patch and use the
>> facility it provides to solve your problem.
>
> Thanks, that seems very reasonable to me, too.
>
> Are you going to pick up revitalizing this patch series or are you
> hoping Vikas will? IIRC I was in favor of your patch but it generated
> a whole bunch of discussion and never actually landed.
I will respin it along with few other patches for pinctrl-samsung, but
obviously not before Monday.
Best regards,
Tomasz
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