[PATCH 1/3] drm: Add LCD display clock polarity flags

[Rob Clark]

On Mon, Dec 2, 2013 at 3:01 PM, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Mon, Dec 02, 2013 at 04:39:26PM +0100, Marek Vasut wrote:
>> Add DRM flags for the LCD display clock polarity so the pixelclk-active DT
>> property can be properly handled by drivers using the DRM API.
>
> I still say that not even this should be part of the DRM mode API to
> userspace.  The hint that you're changing the user API is that you're
> modifying a header file below a 'uapi' directory.
>
> The settings of double scan, sync polarity etc are all part of the
> display mode specification (check CEA-861 documents).  Things like
> pixel clock polarity are not part of the mode specification, they're
> a property of the display itself and are independent of the mode.
>
> Therefore, they should not be part of struct drm_mode_modeinfo.

Note that we could make them part of drm_display_mode (but
drm_crtc_convert_to_umode() should filter them out when copying from
drm_mode_modeinfo.. I agree this information should not be coming from
userspace).  Seems like the sort of thing that the bridge or encoder
could set on the adjusted_mode.

BR,
-R


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