[PATCH 1/4] drm/panel/lpm102a188a: Switch to mipi_dsi_generic_write_seq_multi()

[PATCH 1/4] drm/panel/lpm102a188a: Switch to mipi_dsi_generic_write_seq_multi()

[rtapadia730]

From: Rajeev Tapadia <rtapadia730@gmail.com>

Replace deprecated mipi_dsi_generic_write_seq() calls with
mipi_dsi_generic_write_seq_multi(). This avoids hidden early returns
and matches the direction of other panel drivers.

No functional change intended.

Signed-off-by: Rajeev Tapadia <rtapadia730@gmail.com>
---

Question for reviewers:
In this patch, I switched to using mipi_dsi_generic_write_seq_multi().
Currently, if both link1 and link2 return errors, only one error is
reported via accum_err. How should this ideally be handled? Should we
report the first error, the last, or combine them somehow?

 drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c b/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c
index 5f897e143758..982cb61849a0 100644
--- a/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c
+++ b/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c
@@ -162,27 +162,34 @@ static int jdi_setup_symmetrical_split(struct mipi_dsi_device *left,
 static int jdi_write_dcdc_registers(struct jdi_panel *jdi)
 {
 	/* Clear the manufacturer command access protection */
-	mipi_dsi_generic_write_seq(jdi->link1, MCS_CMD_ACS_PROT,
+	struct mipi_dsi_multi_context dsi_ctx1 = {.dsi = jdi->link1};
+	struct mipi_dsi_multi_context dsi_ctx2 = {.dsi = jdi->link2};
+
+	mipi_dsi_generic_write_seq_multi(&dsi_ctx1, MCS_CMD_ACS_PROT,
 				   MCS_CMD_ACS_PROT_OFF);
-	mipi_dsi_generic_write_seq(jdi->link2, MCS_CMD_ACS_PROT,
+	mipi_dsi_generic_write_seq_multi(&dsi_ctx2, MCS_CMD_ACS_PROT,
 				   MCS_CMD_ACS_PROT_OFF);
 	/*
 	 * Change the VGH/VGL divide rations to move the noise generated by the
 	 * TCONN. This should hopefully avoid interaction with the backlight
 	 * controller.
 	 */
-	mipi_dsi_generic_write_seq(jdi->link1, MCS_PWR_CTRL_FUNC,
+	mipi_dsi_generic_write_seq_multi(&dsi_ctx1, MCS_PWR_CTRL_FUNC,
 				   MCS_PWR_CTRL_PARAM1_VGH_330_DIV |
 				   MCS_PWR_CTRL_PARAM1_DEFAULT,
 				   MCS_PWR_CTRL_PARAM2_VGL_410_DIV |
 				   MCS_PWR_CTRL_PARAM2_DEFAULT);
 
-	mipi_dsi_generic_write_seq(jdi->link2, MCS_PWR_CTRL_FUNC,
+	mipi_dsi_generic_write_seq_multi(&dsi_ctx2, MCS_PWR_CTRL_FUNC,
 				   MCS_PWR_CTRL_PARAM1_VGH_330_DIV |
 				   MCS_PWR_CTRL_PARAM1_DEFAULT,
 				   MCS_PWR_CTRL_PARAM2_VGL_410_DIV |
 				   MCS_PWR_CTRL_PARAM2_DEFAULT);
 
+	if (dsi_ctx1.accum_err < 0)
+		return dsi_ctx1.accum_err;
+	if (dsi_ctx2.accum_err < 0)
+		return dsi_ctx2.accum_err;
 	return 0;
 }
 
-- 
2.51.0

[PATCH 2/4] drm/mipi-dsi: remove deprecated write_seq macro and chatty helper

[rtapadia730]

From: Rajeev Tapadia <rtapadia730@gmail.com>

The mipi_dsi_generic_write_seq() macro is non-intuitive because it
returns out of the caller on error, leading to subtle bugs in panel
drivers. Similarly, mipi_dsi_generic_write_chatty() is redundant.

Both are removed in favour of mipi_dsi_generic_write_multi(), which
provides proper error accumulation for multiple DSI writes and is safer
for panel drivers.

Signed-off-by: Rajeev Tapadia <rtapadia730@gmail.com>
---
 drivers/gpu/drm/drm_mipi_dsi.c | 32 +++-----------------------------
 include/drm/drm_mipi_dsi.h     | 23 -----------------------
 2 files changed, 3 insertions(+), 52 deletions(-)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 3a9b3278a6e3..bc847ab5c822 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -773,42 +773,16 @@ ssize_t mipi_dsi_generic_write(struct mipi_dsi_device *dsi, const void *payload,
 EXPORT_SYMBOL(mipi_dsi_generic_write);
 
 /**
- * mipi_dsi_generic_write_chatty() - mipi_dsi_generic_write() w/ an error log
- * @dsi: DSI peripheral device
+ * mipi_dsi_generic_write_multi()
+ * @ctx: Context for multiple DSI transactions
  * @payload: buffer containing the payload
  * @size: size of payload buffer
  *
  * Like mipi_dsi_generic_write() but includes a dev_err()
- * call for you and returns 0 upon success, not the number of bytes sent.
+ * call for you.
  *
  * Return: 0 on success or a negative error code on failure.
  */
-int mipi_dsi_generic_write_chatty(struct mipi_dsi_device *dsi,
-				  const void *payload, size_t size)
-{
-	struct device *dev = &dsi->dev;
-	ssize_t ret;
-
-	ret = mipi_dsi_generic_write(dsi, payload, size);
-	if (ret < 0) {
-		dev_err(dev, "sending generic data %*ph failed: %zd\n",
-			(int)size, payload, ret);
-		return ret;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(mipi_dsi_generic_write_chatty);
-
-/**
- * mipi_dsi_generic_write_multi() - mipi_dsi_generic_write_chatty() w/ accum_err
- * @ctx: Context for multiple DSI transactions
- * @payload: buffer containing the payload
- * @size: size of payload buffer
- *
- * Like mipi_dsi_generic_write_chatty() but deals with errors in a way that
- * makes it convenient to make several calls in a row.
- */
 void mipi_dsi_generic_write_multi(struct mipi_dsi_multi_context *ctx,
 				  const void *payload, size_t size)
 {
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 57a869a6f6e8..e4d26ed7a62a 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -288,8 +288,6 @@ void mipi_dsi_picture_parameter_set_multi(struct mipi_dsi_multi_context *ctx,
 
 ssize_t mipi_dsi_generic_write(struct mipi_dsi_device *dsi, const void *payload,
 			       size_t size);
-int mipi_dsi_generic_write_chatty(struct mipi_dsi_device *dsi,
-				  const void *payload, size_t size);
 void mipi_dsi_generic_write_multi(struct mipi_dsi_multi_context *ctx,
 				  const void *payload, size_t size);
 ssize_t mipi_dsi_generic_read(struct mipi_dsi_device *dsi, const void *params,
@@ -382,27 +380,6 @@ void mipi_dsi_dcs_set_tear_scanline_multi(struct mipi_dsi_multi_context *ctx,
 					  u16 scanline);
 void mipi_dsi_dcs_set_tear_off_multi(struct mipi_dsi_multi_context *ctx);
 
-/**
- * mipi_dsi_generic_write_seq - transmit data using a generic write packet
- *
- * This macro will print errors for you and will RETURN FROM THE CALLING
- * FUNCTION (yes this is non-intuitive) upon error.
- *
- * Because of the non-intuitive return behavior, THIS MACRO IS DEPRECATED.
- * Please replace calls of it with mipi_dsi_generic_write_seq_multi().
- *
- * @dsi: DSI peripheral device
- * @seq: buffer containing the payload
- */
-#define mipi_dsi_generic_write_seq(dsi, seq...)                                \
-	do {                                                                   \
-		static const u8 d[] = { seq };                                 \
-		int ret;                                                       \
-		ret = mipi_dsi_generic_write_chatty(dsi, d, ARRAY_SIZE(d));    \
-		if (ret < 0)                                                   \
-			return ret;                                            \
-	} while (0)
-
 /**
  * mipi_dsi_generic_write_seq_multi - transmit data using a generic write packet
  *
-- 
2.51.0


Test message

[PATCH 3/4] drm/mipi-dsi: remove deprecated mipi_dsi_dcs_write_buffer_chatty

[rtapadia730]

From: Rajeev Tapadia <rtapadia730@gmail.com>

The mipi_dsi_dcs_write_buffer_chatty() helper is redundant and
non-intuitive. It has been removed in favour of
mipi_dsi_dcs_write_buffer_multi(), which handles multiple DSI writes with
proper error accumulation.

Signed-off-by: Rajeev Tapadia <rtapadia730@gmail.com>
---
 drivers/gpu/drm/drm_mipi_dsi.c | 32 ++------------------------------
 include/drm/drm_mipi_dsi.h     |  2 --
 2 files changed, 2 insertions(+), 32 deletions(-)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index bc847ab5c822..c2fcc219cb58 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -926,40 +926,12 @@ ssize_t mipi_dsi_dcs_write_buffer(struct mipi_dsi_device *dsi,
 EXPORT_SYMBOL(mipi_dsi_dcs_write_buffer);
 
 /**
- * mipi_dsi_dcs_write_buffer_chatty - mipi_dsi_dcs_write_buffer() w/ an error log
- * @dsi: DSI peripheral device
- * @data: buffer containing data to be transmitted
- * @len: size of transmission buffer
- *
- * Like mipi_dsi_dcs_write_buffer() but includes a dev_err()
- * call for you and returns 0 upon success, not the number of bytes sent.
- *
- * Return: 0 on success or a negative error code on failure.
- */
-int mipi_dsi_dcs_write_buffer_chatty(struct mipi_dsi_device *dsi,
-				     const void *data, size_t len)
-{
-	struct device *dev = &dsi->dev;
-	ssize_t ret;
-
-	ret = mipi_dsi_dcs_write_buffer(dsi, data, len);
-	if (ret < 0) {
-		dev_err(dev, "sending dcs data %*ph failed: %zd\n",
-			(int)len, data, ret);
-		return ret;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(mipi_dsi_dcs_write_buffer_chatty);
-
-/**
- * mipi_dsi_dcs_write_buffer_multi - mipi_dsi_dcs_write_buffer_chatty() w/ accum_err
+ * mipi_dsi_dcs_write_buffer_multi - mipi_dsi_dcs_write_buffer() w/ accum_err
  * @ctx: Context for multiple DSI transactions
  * @data: buffer containing data to be transmitted
  * @len: size of transmission buffer
  *
- * Like mipi_dsi_dcs_write_buffer_chatty() but deals with errors in a way that
+ * Like mipi_dsi_dcs_write_buffer() but deals with errors in a way that
  * makes it convenient to make several calls in a row.
  */
 void mipi_dsi_dcs_write_buffer_multi(struct mipi_dsi_multi_context *ctx,
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index e4d26ed7a62a..cda981a41bc6 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -326,8 +326,6 @@ enum mipi_dsi_dcs_tear_mode {
 
 ssize_t mipi_dsi_dcs_write_buffer(struct mipi_dsi_device *dsi,
 				  const void *data, size_t len);
-int mipi_dsi_dcs_write_buffer_chatty(struct mipi_dsi_device *dsi,
-				     const void *data, size_t len);
 void mipi_dsi_dcs_write_buffer_multi(struct mipi_dsi_multi_context *ctx,
 				     const void *data, size_t len);
 ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, u8 cmd,
-- 
2.51.0

Test patch

[PATCH 4/4] drm/todo: remove todo entry for deprecated mipi_dsi_*_write_seq()

[rtapadia730]

From: Rajeev Tapadia <rtapadia730@gmail.com>

The todo entry about transitioning from mipi_dsi_*_write_seq() is
completed.

Signed-off-by: Rajeev Tapadia <rtapadia730@gmail.com>
---
 Documentation/gpu/todo.rst | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index be8637da3fe9..76afb8a784e3 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -497,24 +497,6 @@ Contact: Douglas Anderson <dianders@chromium.org>
 
 Level: Intermediate
 
-Transition away from using mipi_dsi_*_write_seq()
--------------------------------------------------
-
-The macros mipi_dsi_generic_write_seq() and mipi_dsi_dcs_write_seq() are
-non-intuitive because, if there are errors, they return out of the *caller's*
-function. We should move all callers to use mipi_dsi_generic_write_seq_multi()
-and mipi_dsi_dcs_write_seq_multi() macros instead.
-
-Once all callers are transitioned, the macros and the functions that they call,
-mipi_dsi_generic_write_chatty() and mipi_dsi_dcs_write_buffer_chatty(), can
-probably be removed. Alternatively, if people feel like the _multi() variants
-are overkill for some use cases, we could keep the mipi_dsi_*_write_seq()
-variants but change them not to return out of the caller.
-
-Contact: Douglas Anderson <dianders@chromium.org>
-
-Level: Starter
-
 Remove devm_drm_put_bridge()
 ----------------------------
 
-- 
2.51.0

Re: [PATCH 1/4] drm/panel/lpm102a188a: Switch to mipi_dsi_generic_write_seq_multi()

[neil.armstrong]

On 9/21/25 20:37, rtapadia730@gmail.com wrote:
> From: Rajeev Tapadia <rtapadia730@gmail.com>
> 
> Replace deprecated mipi_dsi_generic_write_seq() calls with
> mipi_dsi_generic_write_seq_multi(). This avoids hidden early returns
> and matches the direction of other panel drivers.
> 
> No functional change intended.
> 
> Signed-off-by: Rajeev Tapadia <rtapadia730@gmail.com>
> ---
> 
> Question for reviewers:
> In this patch, I switched to using mipi_dsi_generic_write_seq_multi().
> Currently, if both link1 and link2 return errors, only one error is
> reported via accum_err. How should this ideally be handled? Should we
> report the first error, the last, or combine them somehow?

No it's fine, the first error is catched and reported.

The good way to do this is via this macro:

#define mipi_dsi_dual_dcs_write_seq_multi(dsi_ctx, dsi0, dsi1, cmd, seq...)	\
		do {								\
			dsi_ctx.dsi = dsi0;					\
			mipi_dsi_dcs_write_seq_multi(&dsi_ctx, cmd, seq);	\
			dsi_ctx.dsi = dsi1;					\
			mipi_dsi_dcs_write_seq_multi(&dsi_ctx, cmd, seq);	\
		} while (0)

with a single context. The mipi_dsi_dcs_write_seq_multi will print the
error from the proper DSI and the context will have the appropriate error.

Neil

> 
>   drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c | 15 +++++++++++----
>   1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c b/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c
> index 5f897e143758..982cb61849a0 100644
> --- a/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c
> +++ b/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c
> @@ -162,27 +162,34 @@ static int jdi_setup_symmetrical_split(struct mipi_dsi_device *left,
>   static int jdi_write_dcdc_registers(struct jdi_panel *jdi)
>   {
>   	/* Clear the manufacturer command access protection */
> -	mipi_dsi_generic_write_seq(jdi->link1, MCS_CMD_ACS_PROT,
> +	struct mipi_dsi_multi_context dsi_ctx1 = {.dsi = jdi->link1};
> +	struct mipi_dsi_multi_context dsi_ctx2 = {.dsi = jdi->link2};
> +
> +	mipi_dsi_generic_write_seq_multi(&dsi_ctx1, MCS_CMD_ACS_PROT,
>   				   MCS_CMD_ACS_PROT_OFF);
> -	mipi_dsi_generic_write_seq(jdi->link2, MCS_CMD_ACS_PROT,
> +	mipi_dsi_generic_write_seq_multi(&dsi_ctx2, MCS_CMD_ACS_PROT,
>   				   MCS_CMD_ACS_PROT_OFF);
>   	/*
>   	 * Change the VGH/VGL divide rations to move the noise generated by the
>   	 * TCONN. This should hopefully avoid interaction with the backlight
>   	 * controller.
>   	 */
> -	mipi_dsi_generic_write_seq(jdi->link1, MCS_PWR_CTRL_FUNC,
> +	mipi_dsi_generic_write_seq_multi(&dsi_ctx1, MCS_PWR_CTRL_FUNC,
>   				   MCS_PWR_CTRL_PARAM1_VGH_330_DIV |
>   				   MCS_PWR_CTRL_PARAM1_DEFAULT,
>   				   MCS_PWR_CTRL_PARAM2_VGL_410_DIV |
>   				   MCS_PWR_CTRL_PARAM2_DEFAULT);
>   
> -	mipi_dsi_generic_write_seq(jdi->link2, MCS_PWR_CTRL_FUNC,
> +	mipi_dsi_generic_write_seq_multi(&dsi_ctx2, MCS_PWR_CTRL_FUNC,
>   				   MCS_PWR_CTRL_PARAM1_VGH_330_DIV |
>   				   MCS_PWR_CTRL_PARAM1_DEFAULT,
>   				   MCS_PWR_CTRL_PARAM2_VGL_410_DIV |
>   				   MCS_PWR_CTRL_PARAM2_DEFAULT);
>   
> +	if (dsi_ctx1.accum_err < 0)
> +		return dsi_ctx1.accum_err;
> +	if (dsi_ctx2.accum_err < 0)
> +		return dsi_ctx2.accum_err;
>   	return 0;
>   }
>