Re: [PATCH v2 15/20] drm/drv: Call drm_mode_config_create_state() by default

Dmitry Baryshkov
2026-04-21T15:57:51Z

On Tue, Apr 21, 2026 at 05:33:12PM +0200, Thomas Zimmermann wrote:
>
>
> Am 21.04.26 um 15:38 schrieb Thomas Zimmermann:
> > Hi
> >
> > Am 20.03.26 um 17:27 schrieb Maxime Ripard:
> > > Almost all drivers, and our documented skeleton, call
> > > drm_mode_config_reset() prior to calling drm_dev_register() to
> > > initialize its DRM object states.
> > >
> > > Now that we have drm_mode_config_create_state() to create that initial
> > > state if it doesn't exist, we can call it directly in
> > > drm_dev_register(). That way, we know that the initial atomic state will
> > > always be allocated without any boilerplate.
> > >
> > > Signed-off-by: Maxime Ripard <mripard@kernel.org>
> > > ---
> > >   drivers/gpu/drm/drm_drv.c | 4 ++++
> > >   1 file changed, 4 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> > > index 2915118436ce8a6640cfb0c59936031990727ed1..820106d56ab399a39cac56d98662b5ddbcae8ded
> > > 100644
> > > --- a/drivers/gpu/drm/drm_drv.c
> > > +++ b/drivers/gpu/drm/drm_drv.c
> > > @@ -1097,10 +1097,14 @@ int drm_dev_register(struct drm_device *dev,
> > > unsigned long flags)
> > >         if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> > >           ret = drm_modeset_register_all(dev);
> > >           if (ret)
> > >               goto err_unload;
> > > +
> > > +        ret = drm_mode_config_create_state(dev);
> > > +        if (ret)
> > > +            goto err_unload;
> >
> > Way too late. Lets rather go through drivers and call this where they
> > currently call drm_mode_config_reset() for initialization. This can be a
> > single-patch mass conversion IMHO.
>
> On a second thought, can't we modify the suspend code and leave the reset
> as-is for now?  I'd still be interested to use reset as a means of
> initializing the hardware or loading state on probe. So keeping the _reset()
> calls in place might be helpful for that.

But isn't it the expected behaviour? The driver can reset(), but if
it didn't, the default would be to create empty working state. In the
end, the drivers also can call this function to create the state, don't
they (and then perform the readout logic)?

>
> What's the long-term plan here?
>
> Best regards
> Thomas
>
> >
> > Best regards
> > Thomas
> >
> > >       }
> > >       drm_panic_register(dev);
> > >       drm_client_sysrq_register(dev);
> > >         DRM_INFO("Initialized %s %d.%d.%d for %s on minor %d\n",
> > >
> >
>
> --
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
> GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
>
>

--
With best wishes
Dmitry