drm/panel-edp: Abstract out function to set conservative timings

If we're using the generic "edp-panel" compatible string and we fail
to detect an eDP panel then we fall back to conservative timings for
powering up and powering down the panel. Abstract out the function for
setting these timings so it can be used in future patches.

No functional change expected--just code movement.
Reviewed-by: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240325145626.1.I659b2517d9f619d09e804e071591ecab76335dfb@changeid

drivers/gpu/drm/panel/panel-edp.c

@@ -760,6 +760,25 @@ static void panel_edp_parse_panel_timing_node(struct device *dev,
 
 static const struct edp_panel_entry *find_edp_panel(u32 panel_id, const struct drm_edid *edid);
 
+static void panel_edp_set_conservative_timings(struct panel_edp *panel, struct panel_desc *desc)
+{
+	/*
+	 * It's highly likely that the panel will work if we use very
+	 * conservative timings, so let's do that.
+	 *
+	 * Nearly all panels have a "unprepare" delay of 500 ms though
+	 * there are a few with 1000. Let's stick 2000 in just to be
+	 * super conservative.
+	 *
+	 * An "enable" delay of 80 ms seems the most common, but we'll
+	 * throw in 200 ms to be safe.
+	 */
+	desc->delay.unprepare = 2000;
+	desc->delay.enable = 200;
+
+	panel->detected_panel = ERR_PTR(-EINVAL);
+}
+
 static int generic_edp_panel_probe(struct device *dev, struct panel_edp *panel)
 {
 	struct panel_desc *desc;
@@ -816,26 +835,7 @@ static int generic_edp_panel_probe(struct device *dev, struct panel_edp *panel)
 		dev_warn(dev,
 			 "Unknown panel %s %#06x, using conservative timings\n",
 			 vend, product_id);
-
-		/*
-		 * It's highly likely that the panel will work if we use very
-		 * conservative timings, so let's do that. We already know that
-		 * the HPD-related delays must have worked since we got this
-		 * far, so we really just need the "unprepare" / "enable"
-		 * delays. We don't need "prepare_to_enable" since that
-		 * overlaps the "enable" delay anyway.
-		 *
-		 * Nearly all panels have a "unprepare" delay of 500 ms though
-		 * there are a few with 1000. Let's stick 2000 in just to be
-		 * super conservative.
-		 *
-		 * An "enable" delay of 80 ms seems the most common, but we'll
-		 * throw in 200 ms to be safe.
-		 */
-		desc->delay.unprepare = 2000;
-		desc->delay.enable = 200;
-
-		panel->detected_panel = ERR_PTR(-EINVAL);
+		panel_edp_set_conservative_timings(panel, desc);
 	} else {
 		dev_info(dev, "Detected %s %s (%#06x)\n",
 			 vend, panel->detected_panel->ident.name, product_id);