From: Timur Tabi <timur@codeaurora.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: "Thomas Petazzoni" <thomas.petazzoni@free-electrons.com>,
"Linus Walleij" <linus.walleij@linaro.org>,
"Miquèl Raynal" <miquel.raynal@free-electrons.com>,
"Nadav Haklai" <nadavh@marvell.com>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
"Antoine Ténart" <antoine.tenart@free-electrons.com>,
"Gregory CLEMENT" <gregory.clement@free-electrons.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: linux-next regression caused by "gpiolib: request the gpio before querying its direction"
Date: Thu, 31 Aug 2017 08:05:14 -0500 [thread overview]
Message-ID: <4f39d450-bc9c-b9a9-e3f8-b350e1770479@codeaurora.org> (raw)
In-Reply-To: <CAMuHMdXeWBbSkvwh_hpGhPe_s-GA8BptQPJWG_bu0Ln12N93Aw@mail.gmail.com>
On 08/31/2017 04:50 AM, Geert Uytterhoeven wrote:
>> For instance, you may have a timer block which can capture on both
>> edges of an external event signal, which needs the pin to be muxed for
>> that function. However, you need to read the state of the pin, and
>> that is only available through GPIO. Muxing the pin to be a GPIO just
>> because someone requests the GPIO is, imho, ill thought-out and breaks
>> some use cases.
> Yes, reading from the GPIO can work if the pin is muxed to another function.
Well that depends on the hardware. On Qualcomm chips, the you can
technically still read and write from/to the GPIO if it's muxed to some
other function, but the results are meaningless.
--
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc. Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
next prev parent reply other threads:[~2017-08-31 13:05 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-30 9:24 linux-next regression caused by "gpiolib: request the gpio before querying its direction" Thomas Petazzoni
2017-08-30 12:31 ` Timur Tabi
2017-08-30 13:59 ` Gregory CLEMENT
2017-08-30 14:17 ` Thomas Petazzoni
2017-08-30 14:22 ` Timur Tabi
2017-08-30 14:32 ` Thomas Petazzoni
2017-08-30 16:24 ` jmondi
2017-08-30 19:38 ` Geert Uytterhoeven
2017-08-31 7:08 ` Linus Walleij
2017-08-31 7:18 ` Thomas Petazzoni
2017-08-31 7:30 ` Geert Uytterhoeven
2017-08-31 9:22 ` Russell King - ARM Linux
2017-08-31 9:39 ` Thomas Petazzoni
2017-08-31 18:39 ` Timur Tabi
2017-08-31 9:50 ` Geert Uytterhoeven
2017-08-31 13:05 ` Timur Tabi [this message]
2017-08-31 10:08 ` Maxime Ripard
2017-08-31 7:04 ` Linus Walleij
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