Re: [PATCH v2] drm/exynos: Get HDMI version from device tree

[Sylwester Nawrocki <sylvester.nawrocki-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hi,

On 01/08/2013 11:56 PM, Stephen Warren wrote:
> On 01/08/2013 01:16 PM, Sean Paul wrote:
>> Add a property to the hdmi node so we can specify the HDMI version in
>> the device tree instead of just defaulting to v1.4 with the existence of
>> the dt node.
>
> I guess this seems OK to me if required, although I'd certainly like to
> see someone familiar with the Exynos HW confirm whether this should be
> driven purely by DT compatible value for the HDMI IP block instead though.

I think the supported HDMI standard is something that could well be derived
from the compatible property. The IP supporting v1.3 and v1.4 will be
significantly different, so this would anyway already need to be reflected
in the compatible property. The only issue I see here is that people tend
to make the compatible string overly generic, so it is hardly usable for
anything but matching an IP with its driver. For instance for exynos5 we
have now (Documentation/devicetree/bindings/drm/exynos/hdmi.txt):

	compatible = "samsung,exynos5-hdmi";

For Exynos4 series there were already some patches proposed [1], but I 
believe
this isn't a clean solution. Instead of things like:

compatible = "samsung,exynos4-hdmi13";
compatible = "samsung,exynos4-hdmi14";

I would much more like to see the SoC version embedded in the compatible
string, e.g.

compatible = "samsung,exynos4210-hdmi"; /* among others it carries an
					  information this IP supports
					  HDMI v1.3 */	

compatible = "samsung,exynos4212-hdmi"; /* HDMI v1.4, IIRC */

[1] http://www.spinics.net/lists/linux-samsung-soc/msg15289.html

--

Thanks,
Sylwester