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From:   Richard Acayan <mailingradian@gmail.com>
To:     Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Thierry Reding <thierry.reding@gmail.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Joel Selvaraj <jo@jsfamily.in>,
        Robert Chiras <robert.chiras@nxp.com>,
        Emil Velikov <emil.l.velikov@gmail.com>,
        Vinay Simha BN <simhavcs@gmail.com>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Cc:     Daniel Mentz <danielmentz@google.com>,
        Richard Acayan <mailingradian@gmail.com>
Subject: [RFC PATCH] drm/dsi-mipi: Fix byte order of DCS set/get brightness
Date:   Thu, 12 Jan 2023 23:18:48 -0500
Message-Id: <20230113041848.200704-1-mailingradian@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
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From: Daniel Mentz <danielmentz@google.com>

The MIPI DCS specification demands that brightness values are sent in
big endian byte order. It also states that one parameter (i.e. one byte)
shall be sent/received for 8 bit wide values, and two parameters shall
be used for values that are between 9 and 16 bits wide.

Fixes: 1a9d759331b8 ("drm/dsi: Implement DCS set/get display brightness")
Signed-off-by: Daniel Mentz <danielmentz@google.com>
Change-Id: I24306e21ec6a5ff48ea121d977419a81d5b44152
Link: https://android.googlesource.com/kernel/msm/+/754affd62d0ee268c686c53169b1dbb7deac8550
[richard: fix 16-bit brightness_get; change brightness call by all panels on the -next tree]
Signed-off-by: Richard Acayan <mailingradian@gmail.com>
---
 drivers/gpu/drm/drm_mipi_dsi.c                | 44 ++++++++++++++++---
 .../drm/panel/panel-asus-z00t-tm5p5-n35596.c  |  4 +-
 .../gpu/drm/panel/panel-boe-bf060y8m-aj0.c    |  4 +-
 drivers/gpu/drm/panel/panel-ebbg-ft8719.c     |  2 +-
 drivers/gpu/drm/panel/panel-jdi-fhd-r63452.c  |  2 +-
 .../gpu/drm/panel/panel-jdi-lt070me05000.c    |  4 +-
 drivers/gpu/drm/panel/panel-raydium-rm67191.c |  4 +-
 .../gpu/drm/panel/panel-samsung-s6e63j0x03.c  |  2 +-
 drivers/gpu/drm/panel/panel-samsung-sofef00.c |  4 +-
 .../panel/panel-sony-tulip-truly-nt35521.c    |  4 +-
 include/drm/drm_mipi_dsi.h                    |  4 +-
 11 files changed, 55 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 497ef4b6a90a..1e6dbf986d97 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -1180,17 +1180,33 @@ EXPORT_SYMBOL(mipi_dsi_dcs_set_tear_scanline);
  *    display
  * @dsi: DSI peripheral device
  * @brightness: brightness value
+ * @num_params: Number of parameters (bytes) to encode brightness value in. The
+ *              MIPI specification states that one parameter shall be sent for
+ *              devices that support 8-bit brightness levels. For devices that
+ *              support brightness levels wider than 8-bit, two parameters
+ *              shall be sent.
  *
  * Return: 0 on success or a negative error code on failure.
  */
 int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi,
-					u16 brightness)
+					u16 brightness, size_t num_params)
 {
-	u8 payload[2] = { brightness & 0xff, brightness >> 8 };
+	u8 payload[2];
 	ssize_t err;
 
+	switch (num_params) {
+	case 1:
+		payload[0] = brightness & 0xff;
+		break;
+	case 2:
+		payload[0] = brightness >> 8;
+		payload[1] = brightness & 0xff;
+		break;
+	default:
+		return -EINVAL;
+	}
 	err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
-				 payload, sizeof(payload));
+				 payload, num_params);
 	if (err < 0)
 		return err;
 
@@ -1203,16 +1219,25 @@ EXPORT_SYMBOL(mipi_dsi_dcs_set_display_brightness);
  *    of the display
  * @dsi: DSI peripheral device
  * @brightness: brightness value
+ * @num_params: Number of parameters (i.e. bytes) the brightness value is
+ *              encoded in. The MIPI specification states that one parameter
+ *              shall be returned from devices that support 8-bit brightness
+ *              levels. Devices that support brightness levels wider than
+ *              8-bit return two parameters (i.e. bytes).
  *
  * Return: 0 on success or a negative error code on failure.
  */
 int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
-					u16 *brightness)
+					u16 *brightness, size_t num_params)
 {
+	u8 payload[2];
 	ssize_t err;
 
+	if (!(num_params == 1 || num_params == 2))
+		return -EINVAL;
+
 	err = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_DISPLAY_BRIGHTNESS,
-				brightness, sizeof(*brightness));
+				payload, num_params);
 	if (err <= 0) {
 		if (err == 0)
 			err = -ENODATA;
@@ -1220,6 +1245,15 @@ int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
 		return err;
 	}
 
+	switch (num_params) {
+	case 1:
+		*brightness = payload[0];
+		break;
+	case 2:
+		*brightness = (payload[0] << 8) | payload[1];
+		break;
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(mipi_dsi_dcs_get_display_brightness);
diff --git a/drivers/gpu/drm/panel/panel-asus-z00t-tm5p5-n35596.c b/drivers/gpu/drm/panel/panel-asus-z00t-tm5p5-n35596.c
index b3235781e6ba..9f849c68d57c 100644
--- a/drivers/gpu/drm/panel/panel-asus-z00t-tm5p5-n35596.c
+++ b/drivers/gpu/drm/panel/panel-asus-z00t-tm5p5-n35596.c
@@ -220,7 +220,7 @@ static int tm5p5_nt35596_bl_update_status(struct backlight_device *bl)
 
 	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
 
-	ret = mipi_dsi_dcs_set_display_brightness(dsi, brightness);
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, brightness, 1);
 	if (ret < 0)
 		return ret;
 
@@ -237,7 +237,7 @@ static int tm5p5_nt35596_bl_get_brightness(struct backlight_device *bl)
 
 	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
 
-	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness);
+	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness, 1);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/gpu/drm/panel/panel-boe-bf060y8m-aj0.c b/drivers/gpu/drm/panel/panel-boe-bf060y8m-aj0.c
index ad58840eda41..5a0366366055 100644
--- a/drivers/gpu/drm/panel/panel-boe-bf060y8m-aj0.c
+++ b/drivers/gpu/drm/panel/panel-boe-bf060y8m-aj0.c
@@ -253,7 +253,7 @@ static int boe_bf060y8m_aj0_bl_update_status(struct backlight_device *bl)
 	u16 brightness = backlight_get_brightness(bl);
 	int ret;
 
-	ret = mipi_dsi_dcs_set_display_brightness(dsi, brightness);
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, brightness, 1);
 	if (ret < 0)
 		return ret;
 
@@ -266,7 +266,7 @@ static int boe_bf060y8m_aj0_bl_get_brightness(struct backlight_device *bl)
 	u16 brightness;
 	int ret;
 
-	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness);
+	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness, 1);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/gpu/drm/panel/panel-ebbg-ft8719.c b/drivers/gpu/drm/panel/panel-ebbg-ft8719.c
index e85d63a176d0..0666e0390c7c 100644
--- a/drivers/gpu/drm/panel/panel-ebbg-ft8719.c
+++ b/drivers/gpu/drm/panel/panel-ebbg-ft8719.c
@@ -62,7 +62,7 @@ static int ebbg_ft8719_on(struct ebbg_ft8719 *ctx)
 
 	dsi->mode_flags |= MIPI_DSI_MODE_LPM;
 
-	ret = mipi_dsi_dcs_set_display_brightness(dsi, 0x00ff);
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, 0x00ff, 1);
 	if (ret < 0) {
 		dev_err(dev, "Failed to set display brightness: %d\n", ret);
 		return ret;
diff --git a/drivers/gpu/drm/panel/panel-jdi-fhd-r63452.c b/drivers/gpu/drm/panel/panel-jdi-fhd-r63452.c
index d8765b2294fb..47ebf7b7da4a 100644
--- a/drivers/gpu/drm/panel/panel-jdi-fhd-r63452.c
+++ b/drivers/gpu/drm/panel/panel-jdi-fhd-r63452.c
@@ -102,7 +102,7 @@ static int jdi_fhd_r63452_on(struct jdi_fhd_r63452 *ctx)
 		return ret;
 	}
 
-	ret = mipi_dsi_dcs_set_display_brightness(dsi, 0x00ff);
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, 0x00ff, 1);
 	if (ret < 0) {
 		dev_err(dev, "Failed to set display brightness: %d\n", ret);
 		return ret;
diff --git a/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c b/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c
index 8f4f137a2af6..7d2f147a2504 100644
--- a/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c
+++ b/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c
@@ -332,7 +332,7 @@ static int dsi_dcs_bl_get_brightness(struct backlight_device *bl)
 
 	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
 
-	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness);
+	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness, 1);
 	if (ret < 0)
 		return ret;
 
@@ -348,7 +348,7 @@ static int dsi_dcs_bl_update_status(struct backlight_device *bl)
 
 	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
 
-	ret = mipi_dsi_dcs_set_display_brightness(dsi, bl->props.brightness);
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, bl->props.brightness, 1);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/gpu/drm/panel/panel-raydium-rm67191.c b/drivers/gpu/drm/panel/panel-raydium-rm67191.c
index dbb1ed4efbed..00f6bd163af2 100644
--- a/drivers/gpu/drm/panel/panel-raydium-rm67191.c
+++ b/drivers/gpu/drm/panel/panel-raydium-rm67191.c
@@ -473,7 +473,7 @@ static int rad_bl_get_brightness(struct backlight_device *bl)
 
 	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
 
-	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness);
+	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness, 1);
 	if (ret < 0)
 		return ret;
 
@@ -493,7 +493,7 @@ static int rad_bl_update_status(struct backlight_device *bl)
 
 	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
 
-	ret = mipi_dsi_dcs_set_display_brightness(dsi, bl->props.brightness);
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, bl->props.brightness, 1);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/gpu/drm/panel/panel-samsung-s6e63j0x03.c b/drivers/gpu/drm/panel/panel-samsung-s6e63j0x03.c
index e06fd35de814..f5e235db7ad2 100644
--- a/drivers/gpu/drm/panel/panel-samsung-s6e63j0x03.c
+++ b/drivers/gpu/drm/panel/panel-samsung-s6e63j0x03.c
@@ -365,7 +365,7 @@ static int s6e63j0x03_enable(struct drm_panel *panel)
 		return ret;
 
 	/* set default white brightness */
-	ret = mipi_dsi_dcs_set_display_brightness(dsi, 0x00ff);
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, 0x00ff, 1);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/gpu/drm/panel/panel-samsung-sofef00.c b/drivers/gpu/drm/panel/panel-samsung-sofef00.c
index 1a0d24595faa..b481195c9b8f 100644
--- a/drivers/gpu/drm/panel/panel-samsung-sofef00.c
+++ b/drivers/gpu/drm/panel/panel-samsung-sofef00.c
@@ -224,10 +224,8 @@ static int sofef00_panel_bl_update_status(struct backlight_device *bl)
 	u16 brightness;
 
 	brightness = (u16)backlight_get_brightness(bl);
-	// This panel needs the high and low bytes swapped for the brightness value
-	brightness = __swab16(brightness);
 
-	err = mipi_dsi_dcs_set_display_brightness(dsi, brightness);
+	err = mipi_dsi_dcs_set_display_brightness(dsi, brightness, 2);
 	if (err < 0)
 		return err;
 
diff --git a/drivers/gpu/drm/panel/panel-sony-tulip-truly-nt35521.c b/drivers/gpu/drm/panel/panel-sony-tulip-truly-nt35521.c
index fa9be3c299c0..dbf179fdda88 100644
--- a/drivers/gpu/drm/panel/panel-sony-tulip-truly-nt35521.c
+++ b/drivers/gpu/drm/panel/panel-sony-tulip-truly-nt35521.c
@@ -420,7 +420,7 @@ static int truly_nt35521_bl_update_status(struct backlight_device *bl)
 	u16 brightness = backlight_get_brightness(bl);
 	int ret;
 
-	ret = mipi_dsi_dcs_set_display_brightness(dsi, brightness);
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, brightness, 1);
 	if (ret < 0)
 		return ret;
 
@@ -433,7 +433,7 @@ static int truly_nt35521_bl_get_brightness(struct backlight_device *bl)
 	u16 brightness;
 	int ret;
 
-	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness);
+	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness, 1);
 	if (ret < 0)
 		return ret;
 
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 4f503d99f668..da02f09f251b 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -293,9 +293,9 @@ int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
 int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format);
 int mipi_dsi_dcs_set_tear_scanline(struct mipi_dsi_device *dsi, u16 scanline);
 int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi,
-					u16 brightness);
+					u16 brightness, size_t num_params);
 int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
-					u16 *brightness);
+					u16 *brightness, size_t num_params);
 
 /**
  * mipi_dsi_generic_write_seq - transmit data using a generic write packet
-- 
2.39.0