Re: [PATCH v2 16/27] drm/tegra: Add Tegra114 display controller support

[Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

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On Fri, Oct 11, 2013 at 04:14:27PM -0600, Stephen Warren wrote:
> On 10/07/2013 02:34 AM, Thierry Reding wrote:
> > From: Mikko Perttunen <mperttunen-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> > 
> > The Tegra114 display controller is backwards-compatible with previous
> > generations of the Tegra SoC. No code changes are required.
> 
> If the HW is backwards-compatible, then there's no need to add extra
> compatible values to the driver; just write the following in the DT, and
> it'll just work:
> 
> compatible = "nvidia,tegra114-dc", "nvidia,tegra30-dc";

One reason why I thought it might be useful to still include this, even
though unnecessary, was to match it to the host1x_drm_subdevs table. We
can probably remove the entry from there as well, though.

As far as I can tell, the same holds for Tegra30, which is also
backwards compatible with Tegra20 but the DTS doesn't contain the
Tegra20 compatible. So to keep ABI compatibility we'll need to keep the
nvidia,tegra30-dc in the driver's match tables, but I could still update
the DTS to include the nvidia,tegra20-dc for correctness.

Does that make sense?

Thierry

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