From: tomi.valkeinen@ti•com (Tomi Valkeinen)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 3/3] ARM: OMAP2: omap4-sdp: remove unneeded gpios from dss-common
Date: Fri, 25 Oct 2013 14:17:14 +0300 [thread overview]
Message-ID: <526A533A.6080903@ti.com> (raw)
In-Reply-To: <526A528C.2020204@ti.com>
On 25/10/13 14:14, Nishanth Menon wrote:
> one additional angle before I forget - this is something we do as part
> of power optimization - to identify pins which are programmed for a
> pull in non-functional scenario as it has direct impact on idle power
> numbers.
>
> For example patch #3 in this series
> &omap4_pmx_core {
> pinctrl-0
> ...
> &lcd2_pins
> ..
> }
> &lcd2_pins
>
> lcd2_pins: pinmux_lcd2_pins {
> + pinctrl-single,pins = <
> + 0x20 (PIN_OUTPUT_PULLDOWN | MUX_MODE3) /* gpio_40 */
> + 0x46 (PIN_OUTPUT_PULLUP | MUX_MODE3) /* gpio_59 */
> + 0x56 (PIN_OUTPUT_PULLDOWN | MUX_MODE3) /* gpio_104 */
> + >;
>
> 3 pins are driven around 300uA at boot, even with display OFF -> which
> means wasted current that could have been optimized by hooking the pin
> to the dts node corresponding to the device and used by the driver
> appropriately.
>
> Unfortunately, folks feel simplifying the driver is traditionally a
> better alternative but with a 400 odd pins on a typical SoC of today,
> these defaults add up and end user tends to suffer with bad overall
> power numbers :(..
Good point. I guess that also makes my point of having default values
for GPIOs a bit silly. Driving the GPIO high by default would be ever
worse than the mux pull-up, I believe.
Tomi
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next prev parent reply other threads:[~2013-10-25 11:17 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-25 10:07 [PATCH 1/3] ARM: dts: omap4-panda: add DPI pinmuxing Tomi Valkeinen
2013-10-25 10:07 ` [PATCH 2/3] ARM: dts: omap4-sdp: add LCD pinmuxing Tomi Valkeinen
2013-10-25 10:07 ` [PATCH 3/3] ARM: OMAP2: omap4-sdp: remove unneeded gpios from dss-common Tomi Valkeinen
2013-10-25 10:18 ` Nishanth Menon
2013-10-25 10:25 ` Tomi Valkeinen
2013-10-25 10:54 ` Nishanth Menon
2013-10-25 11:13 ` Tomi Valkeinen
2013-10-25 11:21 ` Nishanth Menon
2013-10-25 11:33 ` Tomi Valkeinen
2013-10-25 11:14 ` Nishanth Menon
2013-10-25 11:17 ` Tomi Valkeinen [this message]
2013-10-25 11:46 ` Tomi Valkeinen
2013-10-25 15:24 ` Nishanth Menon
2013-10-29 10:15 ` [PATCH 1/3] ARM: dts: omap4-panda: add DPI pinmuxing Tomi Valkeinen
2013-10-29 21:25 ` Tony Lindgren
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