[PATCHv2,11/56] drm/omap: dsi: simplify write function
diff mbox series

Message ID 20200224232126.3385250-12-sebastian.reichel@collabora.com
State New
Headers show
Series
  • drm/omap: Convert DSI code to use drm_mipi_dsi and drm_panel
Related show

Commit Message

sre@kernel.org Feb. 24, 2020, 11:20 p.m. UTC
Simplify the write related messages handling by using the functionality
provided by CONFIG_DRM_MIPI_DSI.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
---
 drivers/gpu/drm/omapdrm/dss/Kconfig |   1 +
 drivers/gpu/drm/omapdrm/dss/dsi.c   | 144 +++++++---------------------
 2 files changed, 33 insertions(+), 112 deletions(-)

Comments

Laurent Pinchart Feb. 25, 2020, 3:31 p.m. UTC | #1
Hi Sebastian,

Thank you for the patch.

On Tue, Feb 25, 2020 at 12:20:41AM +0100, Sebastian Reichel wrote:
> Simplify the write related messages handling by using the functionality
> provided by CONFIG_DRM_MIPI_DSI.
> 
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
> ---
>  drivers/gpu/drm/omapdrm/dss/Kconfig |   1 +
>  drivers/gpu/drm/omapdrm/dss/dsi.c   | 144 +++++++---------------------
>  2 files changed, 33 insertions(+), 112 deletions(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/dss/Kconfig b/drivers/gpu/drm/omapdrm/dss/Kconfig
> index 72ae79c0c9b4..90e2dd522896 100644
> --- a/drivers/gpu/drm/omapdrm/dss/Kconfig
> +++ b/drivers/gpu/drm/omapdrm/dss/Kconfig
> @@ -95,6 +95,7 @@ config OMAP2_DSS_SDI
>  config OMAP2_DSS_DSI
>  	bool "DSI support"
>  	default n
> +	select DRM_MIPI_DSI
>  	help
>  	  MIPI DSI (Display Serial Interface) support.
>  
> diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
> index 8c223b808740..e5589e615808 100644
> --- a/drivers/gpu/drm/omapdrm/dss/dsi.c
> +++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
> @@ -2696,97 +2696,49 @@ static int dsi_vc_send_null(struct dsi_data *dsi, int channel)
>  	return dsi_vc_send_long(dsi, channel, MIPI_DSI_NULL_PACKET, NULL, 0, 0);
>  }
>  
> -static int dsi_vc_write_nosync_common(struct dsi_data *dsi, int channel,
> -				      const u8 *data, int len,
> -				      enum dss_dsi_content_type type)
> +static int dsi_vc_write_common(struct omap_dss_device *dssdev,
> +			       const struct mipi_dsi_msg *msg)
>  {
> +	struct dsi_data *dsi = to_dsi_data(dssdev);
> +	struct mipi_dsi_packet packet;
>  	int r;
>  
> -	if (len == 0) {
> -		BUG_ON(type == DSS_DSI_CONTENT_DCS);
> -		r = dsi_vc_send_short(dsi, channel,
> -				MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM, 0, 0);
> -	} else if (len == 1) {
> -		r = dsi_vc_send_short(dsi, channel,
> -				type == DSS_DSI_CONTENT_GENERIC ?
> -				MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM :
> -				MIPI_DSI_DCS_SHORT_WRITE, data[0], 0);
> -	} else if (len == 2) {
> -		r = dsi_vc_send_short(dsi, channel,
> -				type == DSS_DSI_CONTENT_GENERIC ?
> -				MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM :
> -				MIPI_DSI_DCS_SHORT_WRITE_PARAM,
> -				data[0] | (data[1] << 8), 0);
> +	r = mipi_dsi_create_packet(&packet, msg);
> +	if (r < 0)
> +		return r;
> +
> +	if (mipi_dsi_packet_format_is_short(msg->type)) {
> +		u16 data = packet.header[1] | (packet.header[2] << 8);
> +		r = dsi_vc_send_short(dsi, msg->channel, msg->type, data, 0);

You use the packet for this case only, I think you could simply write

		u16 data = ((msg->tx_len > 0) ? tx[0] : 0)
			 | (((msg->tx_len > 1) ? tx[1] : 0) << 8);
		r = dsi_vc_send_short(dsi, msg->channel, msg->type, data, 0);

>  	} else {
> -		r = dsi_vc_send_long(dsi, channel,
> -				type == DSS_DSI_CONTENT_GENERIC ?
> -				MIPI_DSI_GENERIC_LONG_WRITE :
> -				MIPI_DSI_DCS_LONG_WRITE, data, len, 0);
> +		r = dsi_vc_send_long(dsi, msg->channel, msg->type,
> +						   msg->tx_buf, msg->tx_len, 0);

Indentation.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

>  	}
>  
> -	return r;
> -}
> -
> -static int dsi_vc_dcs_write_nosync(struct omap_dss_device *dssdev, int channel,
> -		const u8 *data, int len)
> -{
> -	struct dsi_data *dsi = to_dsi_data(dssdev);
> -
> -	return dsi_vc_write_nosync_common(dsi, channel, data, len,
> -			DSS_DSI_CONTENT_DCS);
> -}
> -
> -static int dsi_vc_generic_write_nosync(struct omap_dss_device *dssdev, int channel,
> -		const u8 *data, int len)
> -{
> -	struct dsi_data *dsi = to_dsi_data(dssdev);
> -
> -	return dsi_vc_write_nosync_common(dsi, channel, data, len,
> -			DSS_DSI_CONTENT_GENERIC);
> -}
> -
> -static int dsi_vc_write_common(struct omap_dss_device *dssdev,
> -			       int channel, const u8 *data, int len,
> -			       enum dss_dsi_content_type type)
> -{
> -	struct dsi_data *dsi = to_dsi_data(dssdev);
> -	int r;
> +	if (r < 0)
> +		return r;
>  
> -	r = dsi_vc_write_nosync_common(dsi, channel, data, len, type);
> -	if (r)
> -		goto err;
> +	/*
> +	 * we do not always have to do the BTA sync, for example we can
> +	 * improve performance by setting the update window information
> +	 * without sending BTA sync between the commands. In that case
> +	 * we can return earily.

s/earily/early/

Do I understand correctly that this isn't implemented yet ? You should
make it clear in the comment that it's a candidate for a future
optimization.

> +	 */
>  
> -	r = dsi_vc_send_bta_sync(dssdev, channel);
> -	if (r)
> -		goto err;
> +	r = dsi_vc_send_bta_sync(dssdev, msg->channel);
> +	if (r) {
> +		DSSERR("bta sync failed\n");
> +		return r;
> +	}
>  
>  	/* RX_FIFO_NOT_EMPTY */
> -	if (REG_GET(dsi, DSI_VC_CTRL(channel), 20, 20)) {
> +	if (REG_GET(dsi, DSI_VC_CTRL(msg->channel), 20, 20)) {
>  		DSSERR("rx fifo not empty after write, dumping data:\n");
> -		dsi_vc_flush_receive_data(dsi, channel);
> -		r = -EIO;
> -		goto err;
> +		dsi_vc_flush_receive_data(dsi, msg->channel);
> +		return -EIO;
>  	}
>  
>  	return 0;
> -err:
> -	DSSERR("dsi_vc_write_common(ch %d, cmd 0x%02x, len %d) failed\n",
> -			channel, data[0], len);
> -	return r;
> -}
> -
> -static int dsi_vc_dcs_write(struct omap_dss_device *dssdev, int channel,
> -		const u8 *data, int len)
> -{
> -	return dsi_vc_write_common(dssdev, channel, data, len,
> -			DSS_DSI_CONTENT_DCS);
> -}
> -
> -static int dsi_vc_generic_write(struct omap_dss_device *dssdev, int channel,
> -		const u8 *data, int len)
> -{
> -	return dsi_vc_write_common(dssdev, channel, data, len,
> -			DSS_DSI_CONTENT_GENERIC);
>  }
>  
>  static int dsi_vc_dcs_send_read_request(struct dsi_data *dsi, int channel,
> @@ -3008,15 +2960,6 @@ static int dsi_vc_generic_read(struct omap_dss_device *dssdev, int channel,
>  	return 0;
>  }
>  
> -static int dsi_vc_set_max_rx_packet_size(struct omap_dss_device *dssdev, int channel,
> -		u16 len)
> -{
> -	struct dsi_data *dsi = to_dsi_data(dssdev);
> -
> -	return dsi_vc_send_short(dsi, channel,
> -			MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE, len, 0);
> -}
> -
>  static int dsi_enter_ulps(struct dsi_data *dsi)
>  {
>  	DECLARE_COMPLETION_ONSTACK(completion);
> @@ -4811,35 +4754,17 @@ static void dsi_release_vc(struct omap_dss_device *dssdev, int channel)
>  static ssize_t omap_dsi_transfer(struct omap_dss_device *dssdev,
>  				 const struct mipi_dsi_msg *msg)
>  {
> -	/*
> -	 * no_sync can be used to optimize performance by sending
> -	 * e.g. column and page information without syncing in
> -	 * between. It's not absolutley required, so postpone this
> -	 * feature for now.
> -	 */
> -	bool no_sync = false;
> -	u16 val;
> -
>  	switch (msg->type) {
>  	case MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM:
>  	case MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM:
>  	case MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM:
>  	case MIPI_DSI_GENERIC_LONG_WRITE:
> -		if (no_sync)
> -			return dsi_vc_generic_write_nosync(dssdev, msg->channel,
> -				                      msg->tx_buf, msg->tx_len);
> -		else
> -			return dsi_vc_generic_write(dssdev, msg->channel,
> -						    msg->tx_buf, msg->tx_len);
>  	case MIPI_DSI_DCS_SHORT_WRITE:
>  	case MIPI_DSI_DCS_SHORT_WRITE_PARAM:
>  	case MIPI_DSI_DCS_LONG_WRITE:
> -		if (no_sync)
> -			return dsi_vc_dcs_write_nosync(dssdev, msg->channel,
> -						      msg->tx_buf, msg->tx_len);
> -		else
> -			return dsi_vc_dcs_write(dssdev, msg->channel,
> -						msg->tx_buf, msg->tx_len);
> +	case MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE:
> +	case MIPI_DSI_NULL_PACKET:
> +		return dsi_vc_write_common(dssdev, msg);
>  	case MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM:
>  	case MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM:
>  	case MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM:
> @@ -4849,11 +4774,6 @@ static ssize_t omap_dsi_transfer(struct omap_dss_device *dssdev,
>  		return dsi_vc_dcs_read(dssdev, msg->channel,
>  				((u8*) msg->tx_buf)[0],
>  				msg->rx_buf, msg->rx_len);
> -	case MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE:
> -		val = le16_to_cpu(*((__le16*) msg->tx_buf));
> -		return dsi_vc_set_max_rx_packet_size(dssdev, msg->channel, val);
> -	case MIPI_DSI_NULL_PACKET:
> -		return dsi_vc_send_null(to_dsi_data(dssdev), msg->channel);
>  	}
>  
>  	return -EINVAL;
Sebastian Reichel Feb. 26, 2020, 10:46 p.m. UTC | #2
Hi Laurent,

On Tue, Feb 25, 2020 at 05:31:05PM +0200, Laurent Pinchart wrote:
> > +	if (mipi_dsi_packet_format_is_short(msg->type)) {
> > +		u16 data = packet.header[1] | (packet.header[2] << 8);
> > +		r = dsi_vc_send_short(dsi, msg->channel, msg->type, data, 0);
> 
> You use the packet for this case only, I think you could simply write
> 
> 		u16 data = ((msg->tx_len > 0) ? tx[0] : 0)
> 			 | (((msg->tx_len > 1) ? tx[1] : 0) << 8);
> 		r = dsi_vc_send_short(dsi, msg->channel, msg->type, data, 0);

That probably works with 's/tx[/((u8*) msg->tx_buf)[', which looks
really ugly :) This code is further simplified by a further patch,
which forwards the complete message into dsi_vc_send_short().

> >  	} else {
> > -		r = dsi_vc_send_long(dsi, channel,
> > -				type == DSS_DSI_CONTENT_GENERIC ?
> > -				MIPI_DSI_GENERIC_LONG_WRITE :
> > -				MIPI_DSI_DCS_LONG_WRITE, data, len, 0);
> > +		r = dsi_vc_send_long(dsi, msg->channel, msg->type,
> > +						   msg->tx_buf, msg->tx_len, 0);
> 
> Indentation.

Ok.

> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Are you fine with keeping the mipi_dsi_packet, since it will be
removed in a further patch?

> >  	}
> >  
> > -	return r;
> > -}
> > -
> > -static int dsi_vc_dcs_write_nosync(struct omap_dss_device *dssdev, int channel,
> > -		const u8 *data, int len)
> > -{
> > -	struct dsi_data *dsi = to_dsi_data(dssdev);
> > -
> > -	return dsi_vc_write_nosync_common(dsi, channel, data, len,
> > -			DSS_DSI_CONTENT_DCS);
> > -}
> > -
> > -static int dsi_vc_generic_write_nosync(struct omap_dss_device *dssdev, int channel,
> > -		const u8 *data, int len)
> > -{
> > -	struct dsi_data *dsi = to_dsi_data(dssdev);
> > -
> > -	return dsi_vc_write_nosync_common(dsi, channel, data, len,
> > -			DSS_DSI_CONTENT_GENERIC);
> > -}
> > -
> > -static int dsi_vc_write_common(struct omap_dss_device *dssdev,
> > -			       int channel, const u8 *data, int len,
> > -			       enum dss_dsi_content_type type)
> > -{
> > -	struct dsi_data *dsi = to_dsi_data(dssdev);
> > -	int r;
> > +	if (r < 0)
> > +		return r;
> >  
> > -	r = dsi_vc_write_nosync_common(dsi, channel, data, len, type);
> > -	if (r)
> > -		goto err;
> > +	/*
> > +	 * we do not always have to do the BTA sync, for example we can
> > +	 * improve performance by setting the update window information
> > +	 * without sending BTA sync between the commands. In that case
> > +	 * we can return earily.
> 
> s/earily/early/
> 
> Do I understand correctly that this isn't implemented yet ? You should
> make it clear in the comment that it's a candidate for a future
> optimization.

Yes. I forgot the TODO keyword for some reason. Has been quite some
time since I wrote this patch :) I fixed the earily and prefixed the
message with TODO.

-- Sebastian
Laurent Pinchart Feb. 26, 2020, 10:48 p.m. UTC | #3
Hi Sebastian,

On Wed, Feb 26, 2020 at 11:46:43PM +0100, Sebastian Reichel wrote:
> On Tue, Feb 25, 2020 at 05:31:05PM +0200, Laurent Pinchart wrote:
> > > +	if (mipi_dsi_packet_format_is_short(msg->type)) {
> > > +		u16 data = packet.header[1] | (packet.header[2] << 8);
> > > +		r = dsi_vc_send_short(dsi, msg->channel, msg->type, data, 0);
> > 
> > You use the packet for this case only, I think you could simply write
> > 
> > 		u16 data = ((msg->tx_len > 0) ? tx[0] : 0)
> > 			 | (((msg->tx_len > 1) ? tx[1] : 0) << 8);
> > 		r = dsi_vc_send_short(dsi, msg->channel, msg->type, data, 0);
> 
> That probably works with 's/tx[/((u8*) msg->tx_buf)[', which looks
> really ugly :) This code is further simplified by a further patch,
> which forwards the complete message into dsi_vc_send_short().
> 
> > >  	} else {
> > > -		r = dsi_vc_send_long(dsi, channel,
> > > -				type == DSS_DSI_CONTENT_GENERIC ?
> > > -				MIPI_DSI_GENERIC_LONG_WRITE :
> > > -				MIPI_DSI_DCS_LONG_WRITE, data, len, 0);
> > > +		r = dsi_vc_send_long(dsi, msg->channel, msg->type,
> > > +						   msg->tx_buf, msg->tx_len, 0);
> > 
> > Indentation.
> 
> Ok.
> 
> > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> 
> Are you fine with keeping the mipi_dsi_packet, since it will be
> removed in a further patch?

Yes, please ignore the comments related to the packet structure, I've
realized when reviewing a patch further in this series that this goes
away (I've mentioned that explicitly in the review of that patch).

> > >  	}
> > >  
> > > -	return r;
> > > -}
> > > -
> > > -static int dsi_vc_dcs_write_nosync(struct omap_dss_device *dssdev, int channel,
> > > -		const u8 *data, int len)
> > > -{
> > > -	struct dsi_data *dsi = to_dsi_data(dssdev);
> > > -
> > > -	return dsi_vc_write_nosync_common(dsi, channel, data, len,
> > > -			DSS_DSI_CONTENT_DCS);
> > > -}
> > > -
> > > -static int dsi_vc_generic_write_nosync(struct omap_dss_device *dssdev, int channel,
> > > -		const u8 *data, int len)
> > > -{
> > > -	struct dsi_data *dsi = to_dsi_data(dssdev);
> > > -
> > > -	return dsi_vc_write_nosync_common(dsi, channel, data, len,
> > > -			DSS_DSI_CONTENT_GENERIC);
> > > -}
> > > -
> > > -static int dsi_vc_write_common(struct omap_dss_device *dssdev,
> > > -			       int channel, const u8 *data, int len,
> > > -			       enum dss_dsi_content_type type)
> > > -{
> > > -	struct dsi_data *dsi = to_dsi_data(dssdev);
> > > -	int r;
> > > +	if (r < 0)
> > > +		return r;
> > >  
> > > -	r = dsi_vc_write_nosync_common(dsi, channel, data, len, type);
> > > -	if (r)
> > > -		goto err;
> > > +	/*
> > > +	 * we do not always have to do the BTA sync, for example we can
> > > +	 * improve performance by setting the update window information
> > > +	 * without sending BTA sync between the commands. In that case
> > > +	 * we can return earily.
> > 
> > s/earily/early/
> > 
> > Do I understand correctly that this isn't implemented yet ? You should
> > make it clear in the comment that it's a candidate for a future
> > optimization.
> 
> Yes. I forgot the TODO keyword for some reason. Has been quite some
> time since I wrote this patch :) I fixed the earily and prefixed the
> message with TODO.

Patch
diff mbox series

diff --git a/drivers/gpu/drm/omapdrm/dss/Kconfig b/drivers/gpu/drm/omapdrm/dss/Kconfig
index 72ae79c0c9b4..90e2dd522896 100644
--- a/drivers/gpu/drm/omapdrm/dss/Kconfig
+++ b/drivers/gpu/drm/omapdrm/dss/Kconfig
@@ -95,6 +95,7 @@  config OMAP2_DSS_SDI
 config OMAP2_DSS_DSI
 	bool "DSI support"
 	default n
+	select DRM_MIPI_DSI
 	help
 	  MIPI DSI (Display Serial Interface) support.
 
diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
index 8c223b808740..e5589e615808 100644
--- a/drivers/gpu/drm/omapdrm/dss/dsi.c
+++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
@@ -2696,97 +2696,49 @@  static int dsi_vc_send_null(struct dsi_data *dsi, int channel)
 	return dsi_vc_send_long(dsi, channel, MIPI_DSI_NULL_PACKET, NULL, 0, 0);
 }
 
-static int dsi_vc_write_nosync_common(struct dsi_data *dsi, int channel,
-				      const u8 *data, int len,
-				      enum dss_dsi_content_type type)
+static int dsi_vc_write_common(struct omap_dss_device *dssdev,
+			       const struct mipi_dsi_msg *msg)
 {
+	struct dsi_data *dsi = to_dsi_data(dssdev);
+	struct mipi_dsi_packet packet;
 	int r;
 
-	if (len == 0) {
-		BUG_ON(type == DSS_DSI_CONTENT_DCS);
-		r = dsi_vc_send_short(dsi, channel,
-				MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM, 0, 0);
-	} else if (len == 1) {
-		r = dsi_vc_send_short(dsi, channel,
-				type == DSS_DSI_CONTENT_GENERIC ?
-				MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM :
-				MIPI_DSI_DCS_SHORT_WRITE, data[0], 0);
-	} else if (len == 2) {
-		r = dsi_vc_send_short(dsi, channel,
-				type == DSS_DSI_CONTENT_GENERIC ?
-				MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM :
-				MIPI_DSI_DCS_SHORT_WRITE_PARAM,
-				data[0] | (data[1] << 8), 0);
+	r = mipi_dsi_create_packet(&packet, msg);
+	if (r < 0)
+		return r;
+
+	if (mipi_dsi_packet_format_is_short(msg->type)) {
+		u16 data = packet.header[1] | (packet.header[2] << 8);
+		r = dsi_vc_send_short(dsi, msg->channel, msg->type, data, 0);
 	} else {
-		r = dsi_vc_send_long(dsi, channel,
-				type == DSS_DSI_CONTENT_GENERIC ?
-				MIPI_DSI_GENERIC_LONG_WRITE :
-				MIPI_DSI_DCS_LONG_WRITE, data, len, 0);
+		r = dsi_vc_send_long(dsi, msg->channel, msg->type,
+						   msg->tx_buf, msg->tx_len, 0);
 	}
 
-	return r;
-}
-
-static int dsi_vc_dcs_write_nosync(struct omap_dss_device *dssdev, int channel,
-		const u8 *data, int len)
-{
-	struct dsi_data *dsi = to_dsi_data(dssdev);
-
-	return dsi_vc_write_nosync_common(dsi, channel, data, len,
-			DSS_DSI_CONTENT_DCS);
-}
-
-static int dsi_vc_generic_write_nosync(struct omap_dss_device *dssdev, int channel,
-		const u8 *data, int len)
-{
-	struct dsi_data *dsi = to_dsi_data(dssdev);
-
-	return dsi_vc_write_nosync_common(dsi, channel, data, len,
-			DSS_DSI_CONTENT_GENERIC);
-}
-
-static int dsi_vc_write_common(struct omap_dss_device *dssdev,
-			       int channel, const u8 *data, int len,
-			       enum dss_dsi_content_type type)
-{
-	struct dsi_data *dsi = to_dsi_data(dssdev);
-	int r;
+	if (r < 0)
+		return r;
 
-	r = dsi_vc_write_nosync_common(dsi, channel, data, len, type);
-	if (r)
-		goto err;
+	/*
+	 * we do not always have to do the BTA sync, for example we can
+	 * improve performance by setting the update window information
+	 * without sending BTA sync between the commands. In that case
+	 * we can return earily.
+	 */
 
-	r = dsi_vc_send_bta_sync(dssdev, channel);
-	if (r)
-		goto err;
+	r = dsi_vc_send_bta_sync(dssdev, msg->channel);
+	if (r) {
+		DSSERR("bta sync failed\n");
+		return r;
+	}
 
 	/* RX_FIFO_NOT_EMPTY */
-	if (REG_GET(dsi, DSI_VC_CTRL(channel), 20, 20)) {
+	if (REG_GET(dsi, DSI_VC_CTRL(msg->channel), 20, 20)) {
 		DSSERR("rx fifo not empty after write, dumping data:\n");
-		dsi_vc_flush_receive_data(dsi, channel);
-		r = -EIO;
-		goto err;
+		dsi_vc_flush_receive_data(dsi, msg->channel);
+		return -EIO;
 	}
 
 	return 0;
-err:
-	DSSERR("dsi_vc_write_common(ch %d, cmd 0x%02x, len %d) failed\n",
-			channel, data[0], len);
-	return r;
-}
-
-static int dsi_vc_dcs_write(struct omap_dss_device *dssdev, int channel,
-		const u8 *data, int len)
-{
-	return dsi_vc_write_common(dssdev, channel, data, len,
-			DSS_DSI_CONTENT_DCS);
-}
-
-static int dsi_vc_generic_write(struct omap_dss_device *dssdev, int channel,
-		const u8 *data, int len)
-{
-	return dsi_vc_write_common(dssdev, channel, data, len,
-			DSS_DSI_CONTENT_GENERIC);
 }
 
 static int dsi_vc_dcs_send_read_request(struct dsi_data *dsi, int channel,
@@ -3008,15 +2960,6 @@  static int dsi_vc_generic_read(struct omap_dss_device *dssdev, int channel,
 	return 0;
 }
 
-static int dsi_vc_set_max_rx_packet_size(struct omap_dss_device *dssdev, int channel,
-		u16 len)
-{
-	struct dsi_data *dsi = to_dsi_data(dssdev);
-
-	return dsi_vc_send_short(dsi, channel,
-			MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE, len, 0);
-}
-
 static int dsi_enter_ulps(struct dsi_data *dsi)
 {
 	DECLARE_COMPLETION_ONSTACK(completion);
@@ -4811,35 +4754,17 @@  static void dsi_release_vc(struct omap_dss_device *dssdev, int channel)
 static ssize_t omap_dsi_transfer(struct omap_dss_device *dssdev,
 				 const struct mipi_dsi_msg *msg)
 {
-	/*
-	 * no_sync can be used to optimize performance by sending
-	 * e.g. column and page information without syncing in
-	 * between. It's not absolutley required, so postpone this
-	 * feature for now.
-	 */
-	bool no_sync = false;
-	u16 val;
-
 	switch (msg->type) {
 	case MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM:
 	case MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM:
 	case MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM:
 	case MIPI_DSI_GENERIC_LONG_WRITE:
-		if (no_sync)
-			return dsi_vc_generic_write_nosync(dssdev, msg->channel,
-				                      msg->tx_buf, msg->tx_len);
-		else
-			return dsi_vc_generic_write(dssdev, msg->channel,
-						    msg->tx_buf, msg->tx_len);
 	case MIPI_DSI_DCS_SHORT_WRITE:
 	case MIPI_DSI_DCS_SHORT_WRITE_PARAM:
 	case MIPI_DSI_DCS_LONG_WRITE:
-		if (no_sync)
-			return dsi_vc_dcs_write_nosync(dssdev, msg->channel,
-						      msg->tx_buf, msg->tx_len);
-		else
-			return dsi_vc_dcs_write(dssdev, msg->channel,
-						msg->tx_buf, msg->tx_len);
+	case MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE:
+	case MIPI_DSI_NULL_PACKET:
+		return dsi_vc_write_common(dssdev, msg);
 	case MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM:
 	case MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM:
 	case MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM:
@@ -4849,11 +4774,6 @@  static ssize_t omap_dsi_transfer(struct omap_dss_device *dssdev,
 		return dsi_vc_dcs_read(dssdev, msg->channel,
 				((u8*) msg->tx_buf)[0],
 				msg->rx_buf, msg->rx_len);
-	case MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE:
-		val = le16_to_cpu(*((__le16*) msg->tx_buf));
-		return dsi_vc_set_max_rx_packet_size(dssdev, msg->channel, val);
-	case MIPI_DSI_NULL_PACKET:
-		return dsi_vc_send_null(to_dsi_data(dssdev), msg->channel);
 	}
 
 	return -EINVAL;