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drm/mipi-dsi: Fix byte order of 16-bit DCS set/get brightness

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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: 1a9d759331 ("drm/dsi: Implement DCS set/get display brightness")
Signed-off-by: Daniel Mentz <danielmentz@google.com>
Link: 754affd62d
[richard: fix 16-bit brightness_get]
Signed-off-by: Richard Acayan <mailingradian@gmail.com>
Tested-by: Caleb Connolly <caleb@connolly.tech>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230116224909.23884-2-mailingradian@gmail.com
This commit is contained in:
Daniel Mentz 2023-01-16 17:49:07 -05:00 committed by Neil Armstrong
parent 13acb368bf
commit c9d27c6be5
2 changed files with 56 additions and 0 deletions
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52
drivers/gpu/drm/drm_mipi_dsi.c
View File

@ -1224,6 +1224,58 @@ 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);

4
include/drm/drm_mipi_dsi.h
View File

@ -296,6 +296,10 @@ 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);
/**
* mipi_dsi_generic_write_seq - transmit data using a generic write packet