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 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
