2023-01-14 01:26:47

by Richard Acayan

Subject: [RFC PATCH v2 1/2] drm/dsi-mipi: Fix byte order of DCS set/get brightness

From: Daniel Mentz <[email protected]>

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 <[email protected]>
Change-Id: I24306e21ec6a5ff48ea121d977419a81d5b44152
Link: https://android.googlesource.com/kernel/msm/+/754affd62d0ee268c686c53169b1dbb7deac8550
[richard: fix 16-bit brightness_get]
[richard: use separate functions instead of switch/case]
Signed-off-by: Richard Acayan <[email protected]>
---
drivers/gpu/drm/drm_mipi_dsi.c | 52 ++++++++++++++++++++++++++++++++++
include/drm/drm_mipi_dsi.h | 4 +++
2 files changed, 56 insertions(+)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 497ef4b6a90a..4bc15fbd009d 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -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);
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 4f503d99f668..16f30975b22b 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -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
--
2.39.0

2023-01-14 02:03:25

by Richard Acayan

Subject: Re: [RFC PATCH v2 1/2] drm/dsi-mipi: Fix byte order of DCS set/get brightness

On Fri, Jan 13, 2023 at 08:00:05PM -0500, Richard Acayan wrote:
> From: Daniel Mentz <[email protected]>
>
> 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 <[email protected]>
> Change-Id: I24306e21ec6a5ff48ea121d977419a81d5b44152
I need to check which local commits I'm actually emailing...

This line will be removed in v3.

> Link: https://android.googlesource.com/kernel/msm/+/754affd62d0ee268c686c53169b1dbb7deac8550
> [richard: fix 16-bit brightness_get]
> [richard: use separate functions instead of switch/case]
> Signed-off-by: Richard Acayan <[email protected]>
> ---
> drivers/gpu/drm/drm_mipi_dsi.c | 52 ++++++++++++++++++++++++++++++++++
> include/drm/drm_mipi_dsi.h | 4 +++
> 2 files changed, 56 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> index 497ef4b6a90a..4bc15fbd009d 100644
> --- a/drivers/gpu/drm/drm_mipi_dsi.c
> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> @@ -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);
> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
> index 4f503d99f668..16f30975b22b 100644
> --- a/include/drm/drm_mipi_dsi.h
> +++ b/include/drm/drm_mipi_dsi.h
> @@ -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
> --
> 2.39.0
>