[RFC PATCH 0/7] add at91sam9 LCDC DRM driver
Sam Ravnborg
sam at ravnborg.org
Fri Aug 24 15:52:46 UTC 2018
Hi Boris.
> >
> > Both devices are supported today by the atmel_lcdfb driver.
> > For this new set of drivers the compatible strings was
> > selected to avoid clash with the existing compatible
> > strings used for the atmel_lcdfb driver to allow them
> > to co-exist.
>
> Hm, I think Rob commented on that already, but we usually try to stay
> compatible with the exisiting/old bindings when introducing a new one.
> Don't know how feasible this is in this particular case though.
I v2 I am working with a backward compatible
approach. This is better that what I cam up with initially.
> > The DRM implementation has a few shortcomings compared to the
> > existing fbdev based driver:
> > - STN displays are not supported
> > Binding support is missing but most of the
> > STN specific functionality is otherwise ported
> > from the fbdev driver.
> > I assume the info should come from the panel
> > but as I lack HW I have not looked too much
> > into what is required.
> > - gamma support is missing
> > The driver utilises drm_simple_kms_helper and
> > this helper lacks support for setting up gamma.
> > If this is useful please let me know and I
> > will extend drm_simple_kms_helper to support this
> > and update the driver.
>
> I guess you can skip that for now.
Also based on feedback from Nicholas the STN parts will be dropped in v2.
For the gamma stuff this looks feasible with a small extension
to drm_simple_kms_helper - but I dunno if this is something that
userspace will actually use.
So that will wait until there is some good reason to implement it,
and I know how to test it too.
>
> > - modesetting is not checked (see TODO in file)
> > Is this required for such a simple setup?
>
> Well, that's always better if you can check that the requested display
> mode is supported before trying to apply it.
I will try to cook up something, have learned a little since posting v1.
>
> > - support for extra modes as applicable (and lcd-wiring-mode)
>
> Peter already suggested something I think.
Yep, plenty of links to read.
Sam
More information about the dri-devel
mailing list