Re: [PATCH] drm/i915/dp: ALPM init to be done after DPCD init

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Mon, 2026-03-02 at 12:50 +0530, Murthy, Arun R wrote:
> On 02-03-2026 12:14, Hogander, Jouni wrote:
> > On Mon, 2026-03-02 at 09:06 +0530, Arun R Murthy wrote:
> > > In ALPM init, the DPCD register ALPM_CAPABILITIES are to be read.
> > > This
> > > read has to happen after the DPCD init.
> > > 
> > > Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
> > > ---
> > >   drivers/gpu/drm/i915/display/intel_dp.c | 4 ++--
> > >   1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > > b/drivers/gpu/drm/i915/display/intel_dp.c
> > > index 613559d11133..e60802b0b8c9 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > > @@ -6948,8 +6948,6 @@ static bool intel_edp_init_connector(struct
> > > intel_dp *intel_dp,
> > >   	 */
> > >   	intel_hpd_enable_detection(encoder);
> > >   
> > > -	intel_alpm_init(intel_dp);
> > > -
> > >   	/* Cache DPCD and EDID for edp. */
> > >   	has_dpcd = intel_edp_init_dpcd(intel_dp, connector);
> > >   
> > > @@ -6961,6 +6959,8 @@ static bool intel_edp_init_connector(struct
> > > intel_dp *intel_dp,
> > >   		goto out_vdd_off;
> > >   	}
> > >   
> > > +	intel_alpm_init(intel_dp);
> > This will cause problems to PSR/Panel Replay. intel_psr_init_dpcd
> > is
> > relying on ALPM dpcd init is done first.
> > 
> > BR,
> > Jouni Högander
> 
> I think this will also have to be moved down.
> 
> For eDP intel_psr_init_dpcd() is called in intel_edp_init_dpcd. 
> So can 
> we move intel_alpm_init inside intel_edp_init_dpcd() ? Just before 
> calling intel_psr_init_dpcd !
> Also rename intel_alpm_init() to intel_alpm_init_dpcd() ?

Animesh has some ongoing work related:

https://patchwork.freedesktop.org/patch/687711/?series=156417&rev=4

I think it should be ok to move and rename it. That mutex_init within
should be handled somehow.

BR,
Jouni Högander

> 
> Thanks and Regards,
> Arun R Murthy
> --------------------
> 
> > > +
> > >   	/*
> > >   	 * VBT and straps are liars. Also check HPD as that
> > > seems
> > >   	 * to be the most reliable piece of information
> > > available.