drm/bridge: ps8640: Add a cache for EDID

When there are multiple EDID reads, the bridge will be repeatedly
enabled and disabled. Add a cache for EDID to speed this up.

Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230315035508.2874915-2-treapking@chromium.org

diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
index 08de501..cddbfe9 100644 (file)
--- a/drivers/gpu/drm/bridge/parade-ps8640.c
+++ b/drivers/gpu/drm/bridge/parade-ps8640.c
@@ -105,6 +105,7 @@ struct ps8640 {
        struct gpio_desc *gpio_reset;
        struct gpio_desc *gpio_powerdown;
        struct device_link *link;
+       struct edid *edid;
        bool pre_enabled;
        bool need_post_hpd_delay;
 };
@@ -543,34 +544,37 @@ static struct edid *ps8640_bridge_get_edid(struct drm_bridge *bridge,
 {
        struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
        bool poweroff = !ps_bridge->pre_enabled;
-       struct edid *edid;
 
-       /*
-        * When we end calling get_edid() triggered by an ioctl, i.e
-        *
-        *   drm_mode_getconnector (ioctl)
-        *     -> drm_helper_probe_single_connector_modes
-        *        -> drm_bridge_connector_get_modes
-        *           -> ps8640_bridge_get_edid
-        *
-        * We need to make sure that what we need is enabled before reading
-        * EDID, for this chip, we need to do a full poweron, otherwise it will
-        * fail.
-        */
-       if (poweroff)
-               drm_atomic_bridge_chain_pre_enable(bridge, connector->state->state);
+       if (!ps_bridge->edid) {
+               /*
+                * When we end calling get_edid() triggered by an ioctl, i.e
+                *
+                *   drm_mode_getconnector (ioctl)
+                *     -> drm_helper_probe_single_connector_modes
+                *        -> drm_bridge_connector_get_modes
+                *           -> ps8640_bridge_get_edid
+                *
+                * We need to make sure that what we need is enabled before
+                * reading EDID, for this chip, we need to do a full poweron,
+                * otherwise it will fail.
+                */
+               if (poweroff)
+                       drm_atomic_bridge_chain_pre_enable(bridge,
+                                                          connector->state->state);
 
-       edid = drm_get_edid(connector,
-                           ps_bridge->page[PAGE0_DP_CNTL]->adapter);
+               ps_bridge->edid = drm_get_edid(connector,
+                                              ps_bridge->page[PAGE0_DP_CNTL]->adapter);
 
-       /*
-        * If we call the get_edid() function without having enabled the chip
-        * before, return the chip to its original power state.
-        */
-       if (poweroff)
-               drm_atomic_bridge_chain_post_disable(bridge, connector->state->state);
+               /*
+                * If we call the get_edid() function without having enabled the
+                * chip before, return the chip to its original power state.
+                */
+               if (poweroff)
+                       drm_atomic_bridge_chain_post_disable(bridge,
+                                                            connector->state->state);
+       }
 
-       return edid;
+       return drm_edid_duplicate(ps_bridge->edid);
 }
 
 static void ps8640_runtime_disable(void *data)
@@ -767,6 +771,13 @@ static int ps8640_probe(struct i2c_client *client)
        return ret;
 }
 
+static void ps8640_remove(struct i2c_client *client)
+{
+       struct ps8640 *ps_bridge = i2c_get_clientdata(client);
+
+       kfree(ps_bridge->edid);
+}
+
 static const struct of_device_id ps8640_match[] = {
        { .compatible = "parade,ps8640" },
        { }
@@ -775,6 +786,7 @@ MODULE_DEVICE_TABLE(of, ps8640_match);
 
 static struct i2c_driver ps8640_driver = {
        .probe_new = ps8640_probe,
+       .remove = ps8640_remove,
        .driver = {
                .name = "ps8640",
                .of_match_table = ps8640_match,