[Intel-gfx] [PATCH] drm/i915/display: Fix shared dpll mismatch for bigjoiner slave

[Navare, Manasi]

On Mon, Jul 19, 2021 at 11:47:51AM +0530, Nautiyal, Ankit K wrote:
> Patch looks good to me.
> 
> Please find below some suggestions
> 
> On 7/15/2021 4:04 AM, Manasi Navare wrote:
> >Currently when we do the HW state readout, we dont set the shared dpll to NULL
> >for the bigjoiner slave which should not have a DPLL assigned. So it has
> >some garbage while the HW state readout is NULL. So explicitly reset
> >the shared dpll for bigjoiner slave pipe.
> >
> >Bug: https://gitlab.freedesktop.org/drm/intel/-/issues/3465
> >Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >Cc: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> >Tested-By: Swati Sharma <swati2.sharma at intel.com>
> checkpatch warning about tested-by tag.
> >Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> >---
> >  drivers/gpu/drm/i915/display/intel_display.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> >diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> >index 65ddb6ca16e6..c274bfb8e549 100644
> >--- a/drivers/gpu/drm/i915/display/intel_display.c
> >+++ b/drivers/gpu/drm/i915/display/intel_display.c
> >@@ -9006,6 +9006,10 @@ verify_crtc_state(struct intel_crtc *crtc,
> >  	if (!new_crtc_state->hw.active)
> >  		return;
> >+	if (new_crtc_state->bigjoiner_slave)
> >+		/* No PLLs set for slave */
> >+		pipe_config->shared_dpll = NULL;
> >+
> 
> there is a check for bigjoiner_slave, couple of lines above this:
> 
> if (new_crtc_state->bigjoiner_slave)
>                 master = new_crtc_state->bigjoiner_linked_crtc;
> 
> Perhaps it will make sense to club the set shared_dpll to NULL, along with
> these lines.

Yup, thats where I was resetting in earlier patch but then it actually gets overridden in a function call
after this point so need to reset it after separately.

Manasi

> 
> In any case:
> 
> Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> 
> >  	intel_pipe_config_sanity_check(dev_priv, pipe_config);
> >  	if (!intel_pipe_config_compare(new_crtc_state,