From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Simon Hatliff <hatliff@cadence.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Alexandre Courbot <gnurou@gmail.com>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Subject: Re: [PATCH 1/2] gpio: Add a driver for Cadence GPIO controller
Date: Fri, 31 Mar 2017 15:28:22 +0200 [thread overview]
Message-ID: <20170331152822.20d30bb4@bbrezillon> (raw)
In-Reply-To: <3422ee23-53b5-8d09-2a5e-d700358ab09d@cadence.com>
On Thu, 30 Mar 2017 18:26:01 +0100
Simon Hatliff <hatliff@cadence.com> wrote:
> > Another solution would be to write 0xffffffff into CDNS_GPIO_OUTPUT_EN
> > at probe time so that each time CDNS_GPIO_DIRECTION_MODE is modified to
> > set a pin in output mode, the CDNS_GPIO_OUTPUT_EN is already correctly
> > configured.
> > Simon, would that work? Is there a good reason to keep a bit in
> > CDNS_GPIO_OUTPUT_EN set to 0 when the GPIO is in input mode (power
> > consumption?)?
> If direction_mode is set to input then output_en is ignored so this
> should work. The hardware defaults to output mode, so as long as you
> set all pins to input mode before you set all output_en bits there
> should be no negative effect.
Okay, I'll try something like that, except I'll probably keep already
output-enabled in their existing state to avoid modifying bootloader's
GPIO settings.
Thanks for the feedback.
Boris
next prev parent reply other threads:[~2017-03-31 13:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-29 16:04 [PATCH 1/2] gpio: Add a driver for Cadence GPIO controller Boris Brezillon
2017-03-29 16:04 ` [PATCH 2/2] dt-bindings: gpio: Document Cadence GPIO controller bindings Boris Brezillon
2017-03-30 8:37 ` Linus Walleij
2017-03-30 9:03 ` [PATCH 1/2] gpio: Add a driver for Cadence GPIO controller Linus Walleij
2017-03-30 11:29 ` Boris Brezillon
2017-03-30 11:51 ` Linus Walleij
2017-03-30 17:26 ` Simon Hatliff
2017-03-31 13:28 ` Boris Brezillon [this message]
2017-04-10 13:26 ` Boris Brezillon
2017-04-24 13:00 ` Linus Walleij
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