linux-kernel - Re: [PATCH 1/2] pinctrl: mediatek: fix direction control issue

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Date:	Fri, 5 Feb 2016 14:52:59 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Hongzhou Yang <hongzhou.yang@...iatek.com>,
	Sherman Yin <syin@...adcom.com>
Cc:	Biao Huang <biao.huang@...iatek.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"moderated list:ARM/Mediatek SoC support" 
	<linux-mediatek@...ts.infradead.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	srv_heupstream@...iatek.com,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Eddie Huang <eddie.huang@...iatek.com>
Subject: Re: [PATCH 1/2] pinctrl: mediatek: fix direction control issue

On Thu, Feb 4, 2016 at 4:03 AM, Hongzhou Yang
<hongzhou.yang@...iatek.com> wrote:
> On Wed, 2016-02-03 at 09:24 +0800, Biao Huang wrote:
>> Since input-enable/disable and input-schmitt-enable/disable are
>> workable when gpio direction is input, so add direction setting
>> when do input-enable/disable and input-schmitt-enable/disable
>> properties.
>>
>> Signed-off-by: Biao Huang <biao.huang@...iatek.com>
>> ---
>>  drivers/pinctrl/mediatek/pinctrl-mtk-common.c |    2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/pinctrl/mediatek/pinctrl-mtk-common.c b/drivers/pinctrl/mediatek/pinctrl-mtk-common.c
>> index 8cac73d..6eb01c9 100644
>> --- a/drivers/pinctrl/mediatek/pinctrl-mtk-common.c
>> +++ b/drivers/pinctrl/mediatek/pinctrl-mtk-common.c
>> @@ -352,6 +352,7 @@ static int mtk_pconf_parse_conf(struct pinctrl_dev *pctldev,
>>               ret = mtk_pconf_set_pull_select(pctl, pin, true, false, arg);
>>               break;
>>       case PIN_CONFIG_INPUT_ENABLE:
>> +             mtk_pmx_gpio_set_direction(pctldev, NULL, pin, true);
>>               ret = mtk_pconf_set_ies_smt(pctl, pin, arg, param);
>
> Hi Linus,
>
> From pinctrl-bindings.txt, 'input-enable' property defined as following:
> input-enable        - enable input on pin (no effect on output)
>
> Since input enable and input direction are two different settings on our
> SOC,

What does this mean? How can input have a "direction"?

Isn't the direction of an input always inbound, into the SoC?

Please elaborate.

> could you tell me the exact meaning of this property? Input enable
> only? Or set input direction at the same time?

This was added in commit 8ba3f4d00078e7a49c60c0bd6298f29402c3a0a0
"pinctrl: Adds slew-rate, input-enable/disable"
by Sherman Yin so let's ask him first.

I interpret it as if there is a single bit setting a pin to input, these
two boolean flags toggle that bit, so it would be the first setting
on your SoC in that case.

Yours,
Linus Walleij