drm/panel: s6e63m0: Don't store+check prepared/enabled

As talked about in commit d2aacaf0 ("drm/panel: Check for already
prepared/enabled in drm_panel"), we want to remove needless code from
panel drivers that was storing and double-checking the
prepared/enabled state. Even if someone was relying on the
double-check before, that double-check is now in the core and not
needed in individual drivers.

For the s6e63m0 panel driver, this actually fixes a subtle/minor error
handling bug in s6e63m0_prepare(). In one error case s6e63m0_prepare()
called s6e63m0_unprepare() directly if there was an error. This call
to s6e63m0_unprepare() would have been a no-op since ctx->prepared
wasn't set yet.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230804140605.RFC.2.Iabafd062e70f6b6b554cf23eeb75f57a80f7e985@changeid

drivers/gpu/drm/panel/panel-samsung-s6e63m0.c

@@ -270,9 +270,6 @@ struct s6e63m0 {
 	struct regulator_bulk_data supplies[2];
 	struct gpio_desc *reset_gpio;
 
-	bool prepared;
-	bool enabled;
-
 	/*
 	 * This field is tested by functions directly accessing bus before
 	 * transfer, transfer is skipped if it is set. In case of transfer
@@ -502,9 +499,6 @@ static int s6e63m0_disable(struct drm_panel *panel)
 {
 	struct s6e63m0 *ctx = panel_to_s6e63m0(panel);
 
-	if (!ctx->enabled)
-		return 0;
-
 	backlight_disable(ctx->bl_dev);
 
 	s6e63m0_dcs_write_seq_static(ctx, MIPI_DCS_SET_DISPLAY_OFF);
@@ -512,8 +506,6 @@ static int s6e63m0_disable(struct drm_panel *panel)
 	s6e63m0_dcs_write_seq_static(ctx, MIPI_DCS_ENTER_SLEEP_MODE);
 	msleep(120);
 
-	ctx->enabled = false;
-
 	return 0;
 }
 
@@ -522,17 +514,12 @@ static int s6e63m0_unprepare(struct drm_panel *panel)
 	struct s6e63m0 *ctx = panel_to_s6e63m0(panel);
 	int ret;
 
-	if (!ctx->prepared)
-		return 0;
-
 	s6e63m0_clear_error(ctx);
 
 	ret = s6e63m0_power_off(ctx);
 	if (ret < 0)
 		return ret;
 
-	ctx->prepared = false;
-
 	return 0;
 }
 
@@ -541,9 +528,6 @@ static int s6e63m0_prepare(struct drm_panel *panel)
 	struct s6e63m0 *ctx = panel_to_s6e63m0(panel);
 	int ret;
 
-	if (ctx->prepared)
-		return 0;
-
 	ret = s6e63m0_power_on(ctx);
 	if (ret < 0)
 		return ret;
@@ -564,8 +548,6 @@ static int s6e63m0_prepare(struct drm_panel *panel)
 	if (ret < 0)
 		s6e63m0_unprepare(panel);
 
-	ctx->prepared = true;
-
 	return ret;
 }
 
@@ -573,9 +555,6 @@ static int s6e63m0_enable(struct drm_panel *panel)
 {
 	struct s6e63m0 *ctx = panel_to_s6e63m0(panel);
 
-	if (ctx->enabled)
-		return 0;
-
 	s6e63m0_dcs_write_seq_static(ctx, MIPI_DCS_EXIT_SLEEP_MODE);
 	msleep(120);
 	s6e63m0_dcs_write_seq_static(ctx, MIPI_DCS_SET_DISPLAY_ON);
@@ -588,8 +567,6 @@ static int s6e63m0_enable(struct drm_panel *panel)
 
 	backlight_enable(ctx->bl_dev);
 
-	ctx->enabled = true;
-
 	return 0;
 }
 
@@ -709,8 +686,6 @@ int s6e63m0_probe(struct device *dev, void *trsp,
 	dev_set_drvdata(dev, ctx);
 
 	ctx->dev = dev;
-	ctx->enabled = false;
-	ctx->prepared = false;
 
 	ret = device_property_read_u32(dev, "max-brightness", &max_brightness);
 	if (ret)