Hm. I'm not sure offhand how to check if drmModeCrtcSetGamma is supported.
I guess you could check if gamma size > 0 or something?

On Thu, Mar 12, 2020, 02:39 Rohit Visavalia <RVISAVAL@xilinx.com> wrote:

> Hi Ilia Mirkin,
>
> Thanks for the review.
>
> By old-fashioned way you mean to say using drmModeCrtcSetGamma()? If yes
> then, it shows error as "failed to set gamma: Function no implemented" if
> any platform specific drm has no gamma property implemented.
>
> Current code shows error while running modetest for Xilinx drm as it
> doesn't supports gamma property and ideally it should not show error as
> gamma is optional property, so it doesn't serve the purpose of optional
> property.
>
> Please correct me if I am missing anything.
>
> Thanks
> Rohit
>
> > -----Original Message-----
> > From: Ilia Mirkin [mailto:imirkin@alum.mit.edu]
> > Sent: Tuesday, March 3, 2020 7:08 PM
> > To: Devarsh Thakkar <DEVARSHT@xilinx.com>
> > Cc: Rohit Visavalia <RVISAVAL@xilinx.com>;
> dri-devel@lists.freedesktop.org;
> > emil.velikov@collabora.com; Ville Syrjälä <ville.syrjala@linux.intel.com>;
> Hyun
> > Kwon <hyunk@xilinx.com>; Ranganathan Sk <rsk@xilinx.com>; Dhaval
> > Rajeshbhai Shah <dshah@xilinx.com>; Varunkumar Allagadapa
> > <VARUNKUM@xilinx.com>
> > Subject: Re: [PATCH libdrm] modetest: call drmModeCrtcSetGamma() only if
> > add_property_optional returns true
> >
> > EXTERNAL EMAIL
> >
> > Pretty sure the current code is right. If the GAMMA_LUT property can't
> be set,
> > it tries to set gamma the old-fashioned way.
> >
> > On Tue, Mar 3, 2020 at 8:12 AM Devarsh Thakkar <DEVARSHT@xilinx.com>
> > wrote:
> > >
> > > Hi Rohit,
> > >
> > > This makes sense to me as gamma was implemented as optional property.
> > > Reviewed-By: "Devarsh Thakkar <devarsh.thakkar@xilinx.com>"
> > >
> > > @emil.velikov@collabora.com, @imirkin@alum.mit.edu, @Ville Syrjälä,
> > Could you please ack and help merge this patch if it also look good to
> you ?
> > >
> > > Regards,
> > > Devarsh
> > >
> > > > -----Original Message-----
> > > > From: Rohit Visavalia
> > > > Sent: 27 February 2020 00:40
> > > > To: Rohit Visavalia <RVISAVAL@xilinx.com>;
> > > > dri-devel@lists.freedesktop.org; imirkin@alum.mit.edu;
> > > > emil.velikov@collabora.com
> > > > Cc: Hyun Kwon <hyunk@xilinx.com>; Ranganathan Sk <rsk@xilinx.com>;
> > > > Dhaval Rajeshbhai Shah <dshah@xilinx.com>; Varunkumar Allagadapa
> > > > <VARUNKUM@xilinx.com>; Devarsh Thakkar <DEVARSHT@xilinx.com>
> > > > Subject: RE: [PATCH libdrm] modetest: call drmModeCrtcSetGamma()
> > > > only if add_property_optional returns true
> > > >
> > > > Gentle reminder.
> > > >
> > > > + Ilia Mirkin, +Emil Velikov.
> > > >
> > > > Thanks & Regards,
> > > > Rohit
> > > >
> > > > > -----Original Message-----
> > > > > From: Rohit Visavalia [mailto:rohit.visavalia@xilinx.com]
> > > > > Sent: Tuesday, February 25, 2020 3:08 PM
> > > > > To: dri-devel@lists.freedesktop.org
> > > > > Cc: Hyun Kwon <hyunk@xilinx.com>; Ranganathan Sk <rsk@xilinx.com>;
> > > > > Dhaval Rajeshbhai Shah <dshah@xilinx.com>; Varunkumar Allagadapa
> > > > > <VARUNKUM@xilinx.com>; Devarsh Thakkar <DEVARSHT@xilinx.com>;
> > > > > Rohit Visavalia <RVISAVAL@xilinx.com>
> > > > > Subject: [PATCH libdrm] modetest: call drmModeCrtcSetGamma() only
> > > > > if add_property_optional returns true
> > > > >
> > > > > gamma is a optional property then also it prints error message, so
> > > > > set gamma only if add_property_optional() returns true.
> > > > >
> > > > > Signed-off-by: Rohit Visavalia <rohit.visavalia@xilinx.com>
> > > > > ---
> > > > >  tests/modetest/modetest.c | 2 +-
> > > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/tests/modetest/modetest.c b/tests/modetest/modetest.c
> > > > > index b907ab3..379b9ea 100644
> > > > > --- a/tests/modetest/modetest.c
> > > > > +++ b/tests/modetest/modetest.c
> > > > > @@ -1138,7 +1138,7 @@ static void set_gamma(struct device *dev,
> > > > > unsigned crtc_id, unsigned fourcc)
> > > > >
> > > > >     add_property_optional(dev, crtc_id, "DEGAMMA_LUT", 0);
> > > > >     add_property_optional(dev, crtc_id, "CTM", 0);
> > > > > -   if (!add_property_optional(dev, crtc_id, "GAMMA_LUT",
> blob_id)) {
> > > > > +   if (add_property_optional(dev, crtc_id, "GAMMA_LUT", blob_id))
> > > > > + {
> > > > >             uint16_t r[256], g[256], b[256];
> > > > >
> > > > >             for (i = 0; i < 256; i++) {
> > > > > --
> > > > > 2.7.4
> > >
>