Re: [Intel-gfx] [PATCH v2] drm/i915/hdcp: Remove drm_modeset_lock in intel_conn_to_vcpi

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Apr 03, 2023 at 12:31:25PM +0530, Suraj Kandpal wrote:
> Remove drm_modeset_lock in intel_conn_to_vcpi as we don't need it
> anymore since all the required locks are taken in atomic check and
> prepare phases.
> 
> --v2
> -take lock if hdcp function is called from legacy path [Ville]
> 
> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_hdcp.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> index 650232c4892b..65cfc4afbcaa 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> @@ -36,13 +36,16 @@ static int intel_conn_to_vcpi(struct intel_connector *connector)
>  	struct drm_dp_mst_atomic_payload *payload;
>  	struct drm_dp_mst_topology_state *mst_state;
>  	int vcpi = 0;
> +	bool is_locked;
>  
>  	/* For HDMI this is forced to be 0x0. For DP SST also this is 0x0. */
>  	if (!connector->port)
>  		return 0;
>  	mgr = connector->port->mgr;
> +	is_locked = drm_modeset_is_locked(&mgr->base.lock);

The fact that *someone* is holding the lock doesn't mean you
can just skip taking it yourself.

> +	if (!is_locked)
> +		drm_modeset_lock(&mgr->base.lock, NULL);
>  
> -	drm_modeset_lock(&mgr->base.lock, NULL);
>  	mst_state = to_drm_dp_mst_topology_state(mgr->base.state);
>  	payload = drm_atomic_get_mst_payload_state(mst_state, connector->port);
>  	if (drm_WARN_ON(mgr->dev, !payload))
> @@ -54,7 +57,9 @@ static int intel_conn_to_vcpi(struct intel_connector *connector)
>  		goto out;
>  	}
>  out:
> -	drm_modeset_unlock(&mgr->base.lock);
> +	if (!is_locked)
> +		drm_modeset_unlock(&mgr->base.lock);
> +
>  	return vcpi;
>  }
>  
> -- 
> 2.25.1

-- 
Ville Syrjälä
Intel