Re: [PATCH v6 10/14] drm/panel: add S6E3FA0 driver

[Thierry Reding <thierry.reding@gmail.com>]

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On Wed, Jul 30, 2014 at 04:44:21PM +0300, Tomi Valkeinen wrote:
> On 22/07/14 10:49, Thierry Reding wrote:
> 
> > But what I was trying to say is that if the Read IDs command isn't an
> > official DCS command, maybe it would be a better idea to use the DDB
> > instead. I assume that even if it isn't the same information it would
> > at least be a superset and therefore a suitable replacement.
> 
> Only if DDB commands work on that panel =). Even if a panel supports
> DCS, it doesn't mean it supports all the commands.

Indeed. I was perhaps a little naïve and assumed this was such a great
standard command that every panel simply had to support it. But so far
I haven't yet come across a single panel that does...

> Also, does it really matter which one to use inside a panel driver? I
> don't really see any pros nor cons with either option. Except, of
> course, if using one of those makes the driver's code simpler.

Yeah, at this point I don't see why the read IDs command shouldn't be
used. It's somewhat unfortunate that it isn't mentioned in the DCS
specification at all, but specifications are only as useful to the
degree that they get implemented...

My hope had been that we would be able to automatically probe for panels
using the DDB, but it seems like that's not a practicable idea given the
almost non-existent support for it.

So as long as we can standardize on common APIs rather than per-driver
implementations, I'm good.

Thierry

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