From: nm@ti•com (Nishanth Menon)
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 06:21:17 -0500 [thread overview]
Message-ID: <526A542D.8060801@ti.com> (raw)
In-Reply-To: <526A526D.3010108@ti.com>
On 10/25/2013 06:13 AM, Tomi Valkeinen wrote:
> On 25/10/13 13:54, Nishanth Menon wrote:
[..]
>
>>>> Could we not use Documentation/devicetree/bindings/gpio/gpio.txt
>>>> binding to map to the right GPIO and drive it using the GPIO module?
>>>
>>> Hmm, what do you mean?
>>>
>>> I do mux the pins to gpios, but there's nothing in the kernel that would
>>> use those gpios. That's why we had the hack above, but I'd love to get
>>> rid of it.
>>>
>>> Can I set the pins to GPIO mode, and set the GPIO to high/low in the .dts?
>>>
>>> If things were perfect, we probably would have a driver for the "switch"
>>> part. I have no idea what kind of driver that would be, though, so at
>>> the moment we've just gone with the use-LCD2-by-default route.
>>
>> I meant you could, in theory provide the gpio numbers and pull
>> directions in dts and allow the init to drive them as needed.
>>
>> Something like:
>> drivers/i2c/busses/i2c-gpio.c as a reference and use
>> of_get_named_gpio/of_get_gpio to pick themup..
>
> I'm still not quite following... What init are you referring to?
>
> The problem here is that the gpios don't really belong to anyone in the
> kernel, as we don't have a driver for the switch.
>
> Or did you mean that we'd still have the code in dss-common.c, but just
> get the gpio numbers from the .dts instead? That makes sense, although
> I'd want to get rid of that code altogether.
>
> Should we have support in the gpio-controller to define default values
> for gpios? I don't think we can rely on the boot loader to set things
> correctly.
>
I am unfortunately, not in a position to know how you plan to
architect dss_common or the various panels associated with it. if you
model these as panels and a generic driver which controls the panel
could request and control pins and gpios as needed I suppose.
gpio controller cannot drive default pull direction, that is the job
of the driver using the gpio.
Simplest example that I can think of to use to point as reference is [1]
[1]
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/leds/leds-gpio.c#n173
--
Regards,
Nishanth Menon
next prev parent reply other threads:[~2013-10-25 11:21 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 [this message]
2013-10-25 11:33 ` Tomi Valkeinen
2013-10-25 11:14 ` Nishanth Menon
2013-10-25 11:17 ` Tomi Valkeinen
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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