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Commit d7ea84cd authored by Daniel Mentz's avatar Daniel Mentz Committed by Greg Kroah-Hartman
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drm/mipi-dsi: Fix byte order of 16-bit DCS set/get brightness 



[ Upstream commit c9d27c6be518b4ef2966d9564654ef99292ea1b3 ]

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.

Add new functions to properly handle 16-bit brightness in big endian,
since the two 8- and 16-bit cases are distinct from each other.

[richard: use separate functions instead of switch/case]
[richard: split into 16-bit component]

Fixes: 1a9d7593 ("drm/dsi: Implement DCS set/get display brightness")
Signed-off-by: default avatarDaniel Mentz <danielmentz@google.com>
Link: https://android.googlesource.com/kernel/msm/+/754affd62d0ee268c686c53169b1dbb7deac8550


[richard: fix 16-bit brightness_get]
Signed-off-by: default avatarRichard Acayan <mailingradian@gmail.com>
Tested-by: default avatarCaleb Connolly <caleb@connolly.tech>
Reviewed-by: default avatarNeil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: default avatarSam Ravnborg <sam@ravnborg.org>
Signed-off-by: default avatarNeil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230116224909.23884-2-mailingradian@gmail.com


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent a9eafb04

drivers/gpu/drm/drm_mipi_dsi.c

+52 −0
Original line number Diff line number Diff line
@@ -1091,6 +1091,58 @@ int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi, 
}

EXPORT_SYMBOL(mipi_dsi_dcs_get_display_brightness);



/**

 * mipi_dsi_dcs_set_display_brightness_large() - sets the 16-bit brightness value

 *    of the display

 * @dsi: DSI peripheral device

 * @brightness: brightness value

 *

 * Return: 0 on success or a negative error code on failure.

 */

int mipi_dsi_dcs_set_display_brightness_large(struct mipi_dsi_device *dsi,

					     u16 brightness)

{

	u8 payload[2] = { brightness >> 8, brightness & 0xff };

	ssize_t err;



	err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,

				 payload, sizeof(payload));

	if (err < 0)

		return err;



	return 0;

}

EXPORT_SYMBOL(mipi_dsi_dcs_set_display_brightness_large);



/**

 * mipi_dsi_dcs_get_display_brightness_large() - gets the current 16-bit

 *    brightness value of the display

 * @dsi: DSI peripheral device

 * @brightness: brightness value

 *

 * Return: 0 on success or a negative error code on failure.

 */

int mipi_dsi_dcs_get_display_brightness_large(struct mipi_dsi_device *dsi,

					     u16 *brightness)

{

	u8 brightness_be[2];

	ssize_t err;



	err = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_DISPLAY_BRIGHTNESS,

				brightness_be, sizeof(brightness_be));

	if (err <= 0) {

		if (err == 0)

			err = -ENODATA;



		return err;

	}



	*brightness = (brightness_be[0] << 8) | brightness_be[1];



	return 0;

}

EXPORT_SYMBOL(mipi_dsi_dcs_get_display_brightness_large);



static int mipi_dsi_drv_probe(struct device *dev)

{

	struct mipi_dsi_driver *drv = to_mipi_dsi_driver(dev->driver);

include/drm/drm_mipi_dsi.h

+4 −0
Original line number Diff line number Diff line
@@ -279,6 +279,10 @@ int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi, 
					u16 brightness);

int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,

					u16 *brightness);

int mipi_dsi_dcs_set_display_brightness_large(struct mipi_dsi_device *dsi,

					     u16 brightness);

int mipi_dsi_dcs_get_display_brightness_large(struct mipi_dsi_device *dsi,

					     u16 *brightness);



/**

 * struct mipi_dsi_driver - DSI driver