On Tue, 2009-02-10 at 22:52 +0530, Hiremath, Vaibhav wrote:
> [Hiremath, Vaibhav] Now I will be following up for OMAP3EVM backlight
> driver patch initiated/posted by Sanjeev. I was just referring to the
> backlight drives currently available under Linux tree, and observed
> that almost all drivers have been implemented in different way. I
> could not able to get one driver to which I can refer to for adding
> support for OMAP3EVM backlight driver.
>
> Can anybody tell me the expected way of implementation for backlight driver
> is?
>
> I have some questions here,
>
> - If I understand correctly (and as mentioned and pointed out by
> Richard in the mail-chain), platform_device should get added in
> platform file where it registers the pointer to the structure "struct
> generic_bl_info".
> This I believe should be standard way everybody should follow, which
> is not the case.
> Am I missing something here?
>
> - The below question may sound foolish, but to is important for me to
> understand the framework.
>
> If I have simple and straight control of backlight, do I really
> required to have separate backlight driver for my platform? Can I make
> use of generic-bl driver?
> The only difference (atleast to my platform) would be the SYSFS entry,
> the entry will get created something like
> /sys/class/backlight/generic-bl/
>
> Is it required to make driver, Power aware and differentiate from generic
> driver?
You should be able to make the driver power aware and still use the
generic driver.
The basic idea is that your platform would register a platform device
and some code to control the backlight, e.g.:
void omap_set_bl_intensity(int X)
{
/* Code to set backlight intensity to X */
}
static struct generic_bl_info bl_platform_data = {
.name = "omap-bl",
.max_intensity = 5,
.default_intensity = 2,
.set_bl_intensity = omap_set_bl_intensity,
};
static struct platform_device backlight_device = {
.name = "generic-bl",
.id = -1,
.dev.platform_data = &bl_platform_data,
};
and that should be all you need as the core class and generic-bl code
will take care of most other things for you. The code above would go
somewhere in arch/arm/mach-omap*/.
If any improvements are needed to generic-bl to make it useful, please
let me know (set_bl_intensity could maybe do with being passed more
information).
Regards,
Richard
--
Richard Purdie
Intel Open Source Technology Centre
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