linux-kernel - Re: [PATCH v4 2/5] drm/drm_property: require DRM_MODE_PROP

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Message-ID: <gbcunf7zmafn5z76mrlgldmsy74s7e6jacv53mgpym2l75uq6h@talxrisbufsw>
Date: Wed, 17 Jul 2024 16:57:26 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Maxime Ripard <mripard@...nel.org>
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Subject: Re: [PATCH v4 2/5] drm/drm_property: require DRM_MODE_PROP_IMMUTABLE
 for single-value props

On Wed, Jul 17, 2024 at 03:42:46PM GMT, Maxime Ripard wrote:
> Hi,
> 
> On Mon, Jul 15, 2024 at 09:33:02AM GMT, Dmitry Baryshkov wrote:
> > Document that DRM_MODE_PROP_IMMUTABLE must be set for the properties
> > that are immutable by definition - e.g. ranges with min == max or enums
> > with a single value. This matches the behaviour of the IGT tests, see
> > kms_properties.c / validate_range_prop(), validate_enum_prop(),
> > validate_bitmask_prop().
> > 
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> 
> We had a discussion yesterday about it on IRC with Sima, Simon and
> Xaver.
> 
> https://oftc.irclog.whitequark.org/dri-devel/2024-07-16#33374622;
> 
> The conclusion was that it would create an inconsistency between drivers
> on whether a given property is immutable or not, which will lead to more
> troubles for userspace.
> 
> It's not clear why Ville added that check in the first place, so the
> best course of action is to remove the IGT test and get the discussion
> started there.

Ack, I'll work on removing those tests later today.

-- 
With best wishes
Dmitry