[PATCH] drm/imx: imx-tve: Make the 'dac' regulator optional

[Philipp Zabel]

On Tue, 2017-02-07 at 18:09 +0100, Lucas Stach wrote:
> Am Dienstag, den 07.02.2017, 17:45 +0100 schrieb Philipp Zabel:
> > On Fri, 2017-02-03 at 10:52 -0200, Fabio Estevam wrote:
> > > Hi Philipp,
> > > 
> > > On Tue, Jan 3, 2017 at 5:11 PM, Fabio Estevam <festevam at gmail.com> wrote:
> > > > From: Fabio Estevam <fabio.estevam at nxp.com>
> > > >
> > > > Commit deb65870b5d9d ("drm/imx: imx-tve: check the value returned by
> > > > regulator_set_voltage()") exposes the following probe issue:
> > > >
> > > > 63ff0000.tve supply dac not found, using dummy regulator
> > > > imx-drm display-subsystem: failed to bind 63ff0000.tve (ops imx_tve_ops): -22
> > > >
> > > > When the 'dac' regulator is not passed in the device tree,
> > > > devm_regulator_get() will return NULL and when regulator_set_voltage()
> > > > is called it returns an error.
> > > >
> > > > Fix the issue by making the 'dac' regulator optional.
> > > >
> > > > Fixes: deb65870b5d9d ("drm/imx: imx-tve: check the value returned by regulator_set_voltage()")
> > > > Cc: <stable at vger.kernel.org> # 4.8+
> > > > Signed-off-by: Fabio Estevam <fabio.estevam at nxp.com>
> > > 
> > > Any comments, please?
> > 
> > I've applied this to the fixes branch, since the current device trees
> > don't have the regulator set.
> > 
> > Is this really optional, though? It would be better to add the correct
> > dac-supply to the device trees.
> > 
> Why does the driver attempt to set the voltage? I guess the voltage is
> fixed, even if it is hooked up to a configurable regulator.

Good point, I suppose what the driver should really do is warn if the
voltage not set correctly?

> Shouldn't we just remove the set_voltage call from the driver and make
> sure the correct voltage is supplied by board level DT constraints?

I think so, yes.

regards
Philipp