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

[Nautiyal, Ankit K]

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.

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,