From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: "zhuchangchun@cvte.com" <zhuchangchun@cvte.com>
Cc: "andriy.shevchenko" <andriy.shevchenko@linux.intel.com>,
"linus.walleij" <linus.walleij@linaro.org>,
linux-gpio <linux-gpio@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
hendychu <hendychu@aliyun.com>
Subject: Re: Re: [PATCH] pinctrl: intel: Implements gpio free function
Date: Thu, 21 Mar 2019 14:03:24 +0200 [thread overview]
Message-ID: <20190321120324.GI3622@lahna.fi.intel.com> (raw)
In-Reply-To: <2019032119195575582546@cvte.com>
On Thu, Mar 21, 2019 at 07:20:56PM +0800, zhuchangchun@cvte.com wrote:
> After you unexport GPIO it can go back to any previous mode it was. If
> you need to use it as GPIO then why unexport it in the first place?
> --> because we need use the GPIO for device reset, we want to recover
> the GPIO value after reset done.If we don't unexport it, then reboot
> the
> intel SOC(not power off), the GPIO's value will stay until the GPIO be
> reinit.
> I tested the GPIO signal with oscilloscope, if power off the SOC,
> then
> power on, the GPIO value can recover its original value. This will
> infruence
> the peripheral device working condition.
If I understand correctly you have some peripheral connected to Intel
based board and one GPIO is used to reset the peripheral.
You say it works fine if you power cycle the board but it does not when
you issue 'reboot' command. Did I understood the problem correctly?
next prev parent reply other threads:[~2019-03-21 12:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-21 2:35 [PATCH] pinctrl: intel: Implements gpio free function zhuchangchun
2019-03-21 8:44 ` Mika Westerberg
2019-03-21 9:23 ` Andy Shevchenko
2019-03-22 18:32 ` Enrico Weigelt, metux IT consult
2019-03-22 19:06 ` Andy Shevchenko
2019-03-25 9:36 ` Enrico Weigelt, metux IT consult
2019-03-25 11:45 ` Andy Shevchenko
2019-04-03 4:13 ` Linus Walleij
2019-04-04 10:51 ` Enrico Weigelt, metux IT consult
2019-04-04 11:52 ` Andy Shevchenko
2019-04-04 16:03 ` Linus Walleij
[not found] ` <2019032119195575582546@cvte.com>
2019-03-21 12:03 ` Mika Westerberg [this message]
[not found] ` <2019032120213955866649@cvte.com>
2019-03-21 12:36 ` Mika Westerberg
[not found] ` <2019032121342663125658@cvte.com>
2019-03-21 13:56 ` Mika Westerberg
[not found] ` <2019032211131426883268@cvte.com>
2019-03-22 10:42 ` Mika Westerberg
[not found] ` <2019032314505202825175@cvte.com>
2019-03-23 16:48 ` andriy.shevchenko
[not found] ` <2019032517511048990383@cvte.com>
2019-03-25 11:48 ` andriy.shevchenko
2019-03-22 18:35 ` Enrico Weigelt, metux IT consult
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