From: Mario Limonciello <[email protected]>

Expose SSD130x contrast through the connector LUMINANCE property when
DRM_LUMINANCE is enabled. Program contrast directly and register the
backlight class device only when DRM_LUMINANCE is disabled, so contrast
has a single owner.

Signed-off-by: Mario Limonciello <[email protected]>
---
v11:
 * Keep selecting BACKLIGHT_CLASS_DEVICE and drop the guards (Sashiko)
 * Register the backlight device only without DRM_LUMINANCE (Sashiko)
 * Initialise the controller with the committed luminance and don't
   clobber the saved contrast on disable (Sashiko)
 * Skip contrast writes while the controller is powered down (Sashiko)
 * Unify contrast dispatch and backlight ops (Sashiko)
 * Drop Reviewed-by due to the rework
v10:
 * Guard the backlight operations and registration with
   BACKLIGHT_CLASS_DEVICE
 * Fix Kconfig recursive issue
 * Add the Reviewed-by tag
---
 drivers/gpu/drm/solomon/ssd130x.c | 149 ++++++++++++++++++++++++--------------
 drivers/gpu/drm/solomon/ssd130x.h |   2 +
 2 files changed, 98 insertions(+), 53 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c 
b/drivers/gpu/drm/solomon/ssd130x.c
index ee43cf0da8792..32e892194f578 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -627,7 +627,7 @@ static int ssd130x_init(struct ssd130x_device *ssd130x)
 static int ssd132x_init(struct ssd130x_device *ssd130x)
 {
        const u8 cmds[] = {
-               2, SSD13XX_CONTRAST, 0x80,
+               2, SSD13XX_CONTRAST, ssd130x->contrast,
                3, SSD132X_SET_COL_RANGE, 0x00, ssd130x->width / 
SSD132X_SEGMENT_WIDTH - 1,
                3, SSD132X_SET_ROW_RANGE, 0x00, ssd130x->height - 1,
                /*
@@ -696,6 +696,18 @@ static int ssd135x_set_contrast(struct ssd130x_device 
*ssd130x, u32 brightness)
        return ssd130x_write_cmd(ssd130x, 4, SSD135X_SET_CONTRAST, a, b, c);
 }
 
+static int ssd130x_set_contrast(struct ssd130x_device *ssd130x, u32 contrast)
+{
+       switch (ssd130x->device_info->family_id) {
+       case SSD133X_FAMILY:
+               return ssd133x_set_contrast(ssd130x, contrast);
+       case SSD135X_FAMILY:
+               return ssd135x_set_contrast(ssd130x, contrast);
+       default:
+               return ssd130x_write_cmd(ssd130x, 2, SSD13XX_CONTRAST, 
contrast);
+       }
+}
+
 static int ssd133x_init(struct ssd130x_device *ssd130x)
 {
        int ret;
@@ -1836,6 +1848,23 @@ static const struct drm_crtc_funcs ssd130x_crtc_funcs = {
        .atomic_destroy_state = ssd130x_crtc_destroy_state,
 };
 
+/*
+ * With DRM_LUMINANCE, initialize the controller with the committed connector
+ * luminance, which may have changed while the display was disabled.
+ */
+static void ssd130x_load_luminance(struct ssd130x_device *ssd130x,
+                                  struct drm_atomic_commit *state)
+{
+       struct drm_connector_state *conn_state;
+
+       if (!IS_ENABLED(CONFIG_DRM_LUMINANCE))
+               return;
+
+       conn_state = drm_atomic_get_new_connector_state(state, 
&ssd130x->connector);
+       if (conn_state)
+               ssd130x->contrast = conn_state->luminance;
+}
+
 static void ssd130x_encoder_atomic_enable(struct drm_encoder *encoder,
                                          struct drm_atomic_commit *state)
 {
@@ -1847,12 +1876,16 @@ static void ssd130x_encoder_atomic_enable(struct 
drm_encoder *encoder,
        if (ret)
                return;
 
+       ssd130x_load_luminance(ssd130x, state);
+
        ret = ssd130x_init(ssd130x);
        if (ret)
                goto power_off;
 
        ssd130x_write_cmd(ssd130x, 1, SSD13XX_DISPLAY_ON);
 
+       ssd130x->enabled = true;
+
        backlight_enable(ssd130x->bl_dev);
 
        return;
@@ -1873,12 +1906,16 @@ static void ssd132x_encoder_atomic_enable(struct 
drm_encoder *encoder,
        if (ret)
                return;
 
+       ssd130x_load_luminance(ssd130x, state);
+
        ret = ssd132x_init(ssd130x);
        if (ret)
                goto power_off;
 
        ssd130x_write_cmd(ssd130x, 1, SSD13XX_DISPLAY_ON);
 
+       ssd130x->enabled = true;
+
        backlight_enable(ssd130x->bl_dev);
 
        return;
@@ -1898,12 +1935,16 @@ static void ssd133x_encoder_atomic_enable(struct 
drm_encoder *encoder,
        if (ret)
                return;
 
+       ssd130x_load_luminance(ssd130x, state);
+
        ret = ssd133x_init(ssd130x);
        if (ret)
                goto power_off;
 
        ssd130x_write_cmd(ssd130x, 1, SSD13XX_DISPLAY_ON);
 
+       ssd130x->enabled = true;
+
        backlight_enable(ssd130x->bl_dev);
 
        return;
@@ -1923,12 +1964,16 @@ static void ssd135x_encoder_atomic_enable(struct 
drm_encoder *encoder,
        if (ret)
                return;
 
+       ssd130x_load_luminance(ssd130x, state);
+
        ret = ssd135x_init(ssd130x);
        if (ret)
                goto power_off;
 
        ssd130x_write_cmd(ssd130x, 1, SSD13XX_DISPLAY_ON);
 
+       ssd130x->enabled = true;
+
        backlight_enable(ssd130x->bl_dev);
 
        return;
@@ -1945,6 +1990,8 @@ static void ssd130x_encoder_atomic_disable(struct 
drm_encoder *encoder,
 
        backlight_disable(ssd130x->bl_dev);
 
+       ssd130x->enabled = false;
+
        ssd130x_write_cmd(ssd130x, 1, SSD13XX_DISPLAY_OFF);
 
        ssd130x_power_off(ssd130x);
@@ -1980,8 +2027,34 @@ static int ssd130x_connector_get_modes(struct 
drm_connector *connector)
        return drm_connector_helper_get_modes_fixed(connector, &ssd130x->mode);
 }
 
+static void ssd130x_connector_set_luminance(const struct drm_connector_state 
*conn_state)
+{
+       struct ssd130x_device *ssd130x = 
drm_to_ssd130x(conn_state->connector->dev);
+
+       /*
+        * The encoder enable already initialized the controller with the
+        * committed luminance. Skip if it failed to power up the controller.
+        */
+       if (!ssd130x->enabled || ssd130x->contrast == conn_state->luminance)
+               return;
+
+       ssd130x->contrast = conn_state->luminance;
+       ssd130x_set_contrast(ssd130x, ssd130x->contrast);
+}
+
+static void ssd130x_connector_disable_luminance(const struct 
drm_connector_state *conn_state)
+{
+       struct ssd130x_device *ssd130x = 
drm_to_ssd130x(conn_state->connector->dev);
+
+       /* Keep ssd130x->contrast, it is restored when the encoder is enabled */
+       if (ssd130x->enabled)
+               ssd130x_set_contrast(ssd130x, 0);
+}
+
 static const struct drm_connector_helper_funcs ssd130x_connector_helper_funcs 
= {
        .get_modes = ssd130x_connector_get_modes,
+       .set_luminance = ssd130x_connector_set_luminance,
+       .disable_luminance = ssd130x_connector_disable_luminance,
 };
 
 static const struct drm_connector_funcs ssd130x_connector_funcs = {
@@ -2016,55 +2089,16 @@ static const struct drm_driver ssd130x_drm_driver = {
 };
 
 static int ssd130x_update_bl(struct backlight_device *bdev)
-{
-       struct ssd130x_device *ssd130x = bl_get_data(bdev);
-       int brightness = backlight_get_brightness(bdev);
-       int ret;
-
-       ssd130x->contrast = brightness;
-
-       ret = ssd130x_write_cmd(ssd130x, 1, SSD13XX_CONTRAST);
-       if (ret < 0)
-               return ret;
-
-       ret = ssd130x_write_cmd(ssd130x, 1, ssd130x->contrast);
-       if (ret < 0)
-               return ret;
-
-       return 0;
-}
-
-static int ssd133x_update_bl(struct backlight_device *bdev)
-{
-       struct ssd130x_device *ssd130x = bl_get_data(bdev);
-
-       ssd130x->contrast = backlight_get_brightness(bdev);
-
-       return ssd133x_set_contrast(ssd130x, ssd130x->contrast);
-}
-
-static int ssd135x_update_bl(struct backlight_device *bdev)
 {
        struct ssd130x_device *ssd130x = bl_get_data(bdev);
 
        ssd130x->contrast = backlight_get_brightness(bdev);
 
-       return ssd135x_set_contrast(ssd130x, ssd130x->contrast);
+       return ssd130x_set_contrast(ssd130x, ssd130x->contrast);
 }
 
-static const struct backlight_ops ssd130xfb_bl_ops[] = {
-       [SSD130X_FAMILY] = {
-               .update_status  = ssd130x_update_bl,
-       },
-       [SSD132X_FAMILY] = {
-               .update_status  = ssd130x_update_bl,
-       },
-       [SSD133X_FAMILY] = {
-               .update_status  = ssd133x_update_bl,
-       },
-       [SSD135X_FAMILY] = {
-               .update_status  = ssd135x_update_bl,
-       },
+static const struct backlight_ops ssd130xfb_bl_ops = {
+       .update_status  = ssd130x_update_bl,
 };
 
 static void ssd130x_parse_properties(struct ssd130x_device *ssd130x)
@@ -2213,6 +2247,13 @@ static int ssd130x_init_modeset(struct ssd130x_device 
*ssd130x)
        }
 
        drm_connector_helper_add(connector, &ssd130x_connector_helper_funcs);
+       if (IS_ENABLED(CONFIG_DRM_LUMINANCE)) {
+               ret = drm_connector_attach_luminance_property(connector, 0,
+                                                             MAX_CONTRAST,
+                                                             
ssd130x->contrast);
+               if (ret)
+                       return ret;
+       }
 
        ret = drm_connector_attach_encoder(connector, encoder);
        if (ret) {
@@ -2270,16 +2311,18 @@ struct ssd130x_device *ssd130x_probe(struct device 
*dev, struct regmap *regmap)
        if (ret)
                return ERR_PTR(ret);
 
-       bl = devm_backlight_device_register(dev, dev_name(dev), dev, ssd130x,
-                                           
&ssd130xfb_bl_ops[ssd130x->device_info->family_id],
-                                           NULL);
-       if (IS_ERR(bl))
-               return ERR_PTR(dev_err_probe(dev, PTR_ERR(bl),
-                                            "Unable to register backlight 
device\n"));
-
-       bl->props.brightness = ssd130x->contrast;
-       bl->props.max_brightness = MAX_CONTRAST;
-       ssd130x->bl_dev = bl;
+       if (!IS_ENABLED(CONFIG_DRM_LUMINANCE)) {
+               bl = devm_backlight_device_register(dev, dev_name(dev), dev,
+                                                   ssd130x, &ssd130xfb_bl_ops,
+                                                   NULL);
+               if (IS_ERR(bl))
+                       return ERR_PTR(dev_err_probe(dev, PTR_ERR(bl),
+                                                    "Unable to register 
backlight device\n"));
+
+               bl->props.brightness = ssd130x->contrast;
+               bl->props.max_brightness = MAX_CONTRAST;
+               ssd130x->bl_dev = bl;
+       }
 
        ret = ssd130x_init_modeset(ssd130x);
        if (ret)
diff --git a/drivers/gpu/drm/solomon/ssd130x.h 
b/drivers/gpu/drm/solomon/ssd130x.h
index fd81262f2ceb9..536a5649edffc 100644
--- a/drivers/gpu/drm/solomon/ssd130x.h
+++ b/drivers/gpu/drm/solomon/ssd130x.h
@@ -100,6 +100,8 @@ struct ssd130x_device {
        u32 prechargep2;
 
        struct backlight_device *bl_dev;
+       /* Controller is powered and initialized, set from atomic commits */
+       bool enabled;
        struct pwm_device *pwm;
        struct gpio_desc *reset;
        struct regulator *vcc_reg;

-- 
2.53.0

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