linux-kernel - [PATCH 1/1] drm/vc4: hdmi: Replace drm_detect_hdmi_monitor() with is

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Date:   Wed,  6 Apr 2022 18:55:14 +0200
From:   José Expósito <jose.exposito89@...il.com>
To:     emma@...olt.net
Cc:     mripard@...nel.org, laurent.pinchart@...asonboard.com,
        airlied@...ux.ie, daniel@...ll.ch, p.zabel@...gutronix.de,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        José Expósito <jose.exposito89@...il.com>
Subject: [PATCH 1/1] drm/vc4: hdmi: Replace drm_detect_hdmi_monitor() with is_hdmi

Once EDID is parsed, the monitor HDMI support information is cached in
drm_display_info.is_hdmi by drm_parse_hdmi_vsdb_video().

This driver calls drm_detect_hdmi_monitor() to receive the same
information and stores its own cached value, which is less efficient.

Avoid calling drm_detect_hdmi_monitor() and use drm_display_info.is_hdmi
instead.

drm_detect_hdmi_monitor() is called in vc4_hdmi_connector_detect() and
vc4_hdmi_connector_get_modes(). In both cases it is safe to rely on
drm_display_info.is_hdmi as shown by ftrace:

vc4_hdmi_connector_detect:

    vc4_hdmi_connector_detect() {
      drm_get_edid() {
        drm_connector_update_edid_property() {
          drm_add_display_info() {
            drm_reset_display_info();
            drm_for_each_detailed_block.part.0();
            drm_parse_cea_ext() {
              drm_find_cea_extension();
              cea_db_offsets.part.0();
              cea_db_is_hdmi_vsdb.part.0();
              drm_parse_hdmi_vsdb_video();
              /* drm_display_info.is_hdmi is cached here */
            }
          }
        }
      }
      /* drm_display_info.is_hdmi is used here */
    }

vc4_hdmi_connector_get_modes:

    vc4_hdmi_connector_get_modes() {
      drm_get_edid() {
        drm_connector_update_edid_property() {
          drm_add_display_info() {
            drm_reset_display_info();
            drm_for_each_detailed_block.part.0();
            drm_parse_cea_ext() {
              drm_find_cea_extension();
              cea_db_offsets.part.0();
              cea_db_is_hdmi_vsdb.part.0();
              drm_parse_hdmi_vsdb_video();
              /* drm_display_info.is_hdmi is cached here */
            }
          }
        }
      }
      /* drm_display_info.is_hdmi is used here */
      drm_connector_update_edid_property();
    }

Signed-off-by: José Expósito <jose.exposito89@...il.com>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 6c58b0fd13fb..ecdb1ffc2023 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -216,7 +216,7 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
 
 			if (edid) {
 				cec_s_phys_addr_from_edid(vc4_hdmi->cec_adap, edid);
-				vc4_hdmi->encoder.hdmi_monitor = drm_detect_hdmi_monitor(edid);
+				vc4_hdmi->encoder.hdmi_monitor = connector->display_info.is_hdmi;
 				kfree(edid);
 			}
 		}
@@ -255,7 +255,7 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
 		goto out;
 	}
 
-	vc4_encoder->hdmi_monitor = drm_detect_hdmi_monitor(edid);
+	vc4_encoder->hdmi_monitor = connector->display_info.is_hdmi;
 
 	drm_connector_update_edid_property(connector, edid);
 	ret = drm_add_edid_modes(connector, edid);
-- 
2.25.1