Hi all,

Today's linux-next merge of the drm tree got a conflict in:

  drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c

between commit:

  cffcb42c57686 ("drm/bridge: dw-hdmi-qp: fix multi-channel audio output")

from the drm-misc-fixes tree and commit:

  3ea699b56d31c ("drm/bridge: dw-hdmi-qp: Rework Audio InfoFrame handler")

from the drm tree.

I fixed it up (see below) and can carry the fix as necessary. This
is now fixed as far as linux-next is concerned, but any non trivial
conflicts should be mentioned to your upstream maintainer when your tree
is submitted for merging.  You may also want to consider cooperating
with the maintainer of the conflicting tree to minimise any particularly
complex conflicts.

diff --combined drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
index facfb7526928d,d649a1cf07f5c..0000000000000
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
@@@ -11,6 -11,7 +11,7 @@@
  #include <linux/export.h>
  #include <linux/i2c.h>
  #include <linux/irq.h>
+ #include <linux/minmax.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/of.h>
@@@ -748,120 -749,6 +749,6 @@@ static struct i2c_adapter *dw_hdmi_qp_i
  	return adap;
  }
  
- static int dw_hdmi_qp_config_avi_infoframe(struct dw_hdmi_qp *hdmi,
- 					   const u8 *buffer, size_t len)
- {
- 	u32 val, i, j;
- 
- 	if (len != HDMI_INFOFRAME_SIZE(AVI)) {
- 		dev_err(hdmi->dev, "failed to configure avi infoframe\n");
- 		return -EINVAL;
- 	}
- 
- 	/*
- 	 * DW HDMI QP IP uses a different byte format from standard AVI info
- 	 * frames, though generally the bits are in the correct bytes.
- 	 */
- 	val = buffer[1] << 8 | buffer[2] << 16;
- 	dw_hdmi_qp_write(hdmi, val, PKT_AVI_CONTENTS0);
- 
- 	for (i = 0; i < 4; i++) {
- 		for (j = 0; j < 4; j++) {
- 			if (i * 4 + j >= 14)
- 				break;
- 			if (!j)
- 				val = buffer[i * 4 + j + 3];
- 			val |= buffer[i * 4 + j + 3] << (8 * j);
- 		}
- 
- 		dw_hdmi_qp_write(hdmi, val, PKT_AVI_CONTENTS1 + i * 4);
- 	}
- 
- 	dw_hdmi_qp_mod(hdmi, 0, PKTSCHED_AVI_FIELDRATE, PKTSCHED_PKT_CONFIG1);
- 
- 	dw_hdmi_qp_mod(hdmi, PKTSCHED_AVI_TX_EN | PKTSCHED_GCP_TX_EN,
- 		       PKTSCHED_AVI_TX_EN | PKTSCHED_GCP_TX_EN, PKTSCHED_PKT_EN);
- 
- 	return 0;
- }
- 
- static int dw_hdmi_qp_config_drm_infoframe(struct dw_hdmi_qp *hdmi,
- 					   const u8 *buffer, size_t len)
- {
- 	u32 val, i;
- 
- 	if (len != HDMI_INFOFRAME_SIZE(DRM)) {
- 		dev_err(hdmi->dev, "failed to configure drm infoframe\n");
- 		return -EINVAL;
- 	}
- 
- 	dw_hdmi_qp_mod(hdmi, 0, PKTSCHED_DRMI_TX_EN, PKTSCHED_PKT_EN);
- 
- 	val = buffer[1] << 8 | buffer[2] << 16;
- 	dw_hdmi_qp_write(hdmi, val, PKT_DRMI_CONTENTS0);
- 
- 	for (i = 0; i <= buffer[2]; i++) {
- 		if (i % 4 == 0)
- 			val = buffer[3 + i];
- 		val |= buffer[3 + i] << ((i % 4) * 8);
- 
- 		if ((i % 4 == 3) || i == buffer[2])
- 			dw_hdmi_qp_write(hdmi, val,
- 					 PKT_DRMI_CONTENTS1 + ((i / 4) * 4));
- 	}
- 
- 	dw_hdmi_qp_mod(hdmi, 0, PKTSCHED_DRMI_FIELDRATE, PKTSCHED_PKT_CONFIG1);
- 	dw_hdmi_qp_mod(hdmi, PKTSCHED_DRMI_TX_EN, PKTSCHED_DRMI_TX_EN,
- 		       PKTSCHED_PKT_EN);
- 
- 	return 0;
- }
- 
- /*
-  * Static values documented in the TRM
-  * Different values are only used for debug purposes
-  */
- #define DW_HDMI_QP_AUDIO_INFOFRAME_HB1	0x1
- #define DW_HDMI_QP_AUDIO_INFOFRAME_HB2	0xa
- 
- static int dw_hdmi_qp_config_audio_infoframe(struct dw_hdmi_qp *hdmi,
- 					     const u8 *buffer, size_t len)
- {
- 	/*
- 	 * AUDI_CONTENTS0: { RSV, HB2, HB1, RSV }
- 	 * AUDI_CONTENTS1: { PB3, PB2, PB1, PB0 }
- 	 * AUDI_CONTENTS2: { PB7, PB6, PB5, PB4 }
- 	 *
- 	 * PB0: CheckSum
- 	 * PB1: | CT3    | CT2  | CT1  | CT0  | F13  | CC2 | CC1 | CC0 |
- 	 * PB2: | F27    | F26  | F25  | SF2  | SF1  | SF0 | SS1 | SS0 |
- 	 * PB3: | F37    | F36  | F35  | F34  | F33  | F32 | F31 | F30 |
- 	 * PB4: | CA7    | CA6  | CA5  | CA4  | CA3  | CA2 | CA1 | CA0 |
- 	 * PB5: | DM_INH | LSV3 | LSV2 | LSV1 | LSV0 | F52 | F51 | F50 |
- 	 * PB6~PB10: Reserved
- 	 *
- 	 * AUDI_CONTENTS0 default value defined by HDMI specification,
- 	 * and shall only be changed for debug purposes.
- 	 */
- 	u32 header_bytes = (DW_HDMI_QP_AUDIO_INFOFRAME_HB1 << 8) |
- 			  (DW_HDMI_QP_AUDIO_INFOFRAME_HB2 << 16);
- 
- 	regmap_bulk_write(hdmi->regm, PKT_AUDI_CONTENTS0, &header_bytes, 1);
- 	regmap_bulk_write(hdmi->regm, PKT_AUDI_CONTENTS1, &buffer[3], 1);
- 	regmap_bulk_write(hdmi->regm, PKT_AUDI_CONTENTS2, &buffer[7], 1);
- 
- 	/* Enable ACR, AUDI, AMD */
- 	dw_hdmi_qp_mod(hdmi,
- 		       PKTSCHED_ACR_TX_EN | PKTSCHED_AUDI_TX_EN | PKTSCHED_AMD_TX_EN,
- 		       PKTSCHED_ACR_TX_EN | PKTSCHED_AUDI_TX_EN | PKTSCHED_AMD_TX_EN,
- 		       PKTSCHED_PKT_EN);
- 
- 	/* Enable AUDS */
- 	dw_hdmi_qp_mod(hdmi, PKTSCHED_AUDS_TX_EN, PKTSCHED_AUDS_TX_EN, PKTSCHED_PKT_EN);
- 
- 	return 0;
- }
- 
  static void dw_hdmi_qp_bridge_atomic_enable(struct drm_bridge *bridge,
  					    struct drm_atomic_state *state)
  {
@@@ -970,9 -857,9 +857,9 @@@ static int dw_hdmi_qp_bridge_clear_avi_
  
  static int dw_hdmi_qp_bridge_clear_hdmi_infoframe(struct drm_bridge *bridge)
  {
- 	/* FIXME: add support for this InfoFrame */
+ 	struct dw_hdmi_qp *hdmi = bridge->driver_private;
  
- 	drm_warn_once(bridge->encoder->dev, "HDMI VSI not supported\n");
+ 	dw_hdmi_qp_mod(hdmi, 0, PKTSCHED_VSI_TX_EN, PKTSCHED_PKT_EN);
  
  	return 0;
  }
@@@ -986,6 -873,15 +873,15 @@@ static int dw_hdmi_qp_bridge_clear_hdr_
  	return 0;
  }
  
+ static int dw_hdmi_qp_bridge_clear_spd_infoframe(struct drm_bridge *bridge)
+ {
+ 	struct dw_hdmi_qp *hdmi = bridge->driver_private;
+ 
+ 	dw_hdmi_qp_mod(hdmi, 0, PKTSCHED_SPDI_TX_EN, PKTSCHED_PKT_EN);
+ 
+ 	return 0;
+ }
+ 
  static int dw_hdmi_qp_bridge_clear_audio_infoframe(struct drm_bridge *bridge)
  {
  	struct dw_hdmi_qp *hdmi = bridge->driver_private;
@@@ -999,6 -895,32 +895,32 @@@
  	return 0;
  }
  
+ static void dw_hdmi_qp_write_pkt(struct dw_hdmi_qp *hdmi, const u8 *buffer,
+ 				 size_t start, size_t len, unsigned int reg)
+ {
+ 	u32 val = 0;
+ 	size_t i;
+ 
+ 	for (i = start; i < start + len; i++)
+ 		val |= buffer[i] << ((i % 4) * BITS_PER_BYTE);
+ 
+ 	dw_hdmi_qp_write(hdmi, val, reg);
+ }
+ 
+ static void dw_hdmi_qp_write_infoframe(struct dw_hdmi_qp *hdmi, const u8 *buffer,
+ 				       size_t len, unsigned int reg)
+ {
+ 	size_t i;
+ 
+ 	/* InfoFrame packet header */
+ 	dw_hdmi_qp_write_pkt(hdmi, buffer, 1, 2, reg);
+ 
+ 	/* InfoFrame packet body */
+ 	for (i = 0; i < len - 3; i += 4)
+ 		dw_hdmi_qp_write_pkt(hdmi, buffer + 3, i, min(len - i - 3, 4),
+ 				     reg + i + 4);
+ }
+ 
  static int dw_hdmi_qp_bridge_write_avi_infoframe(struct drm_bridge *bridge,
  						 const u8 *buffer, size_t len)
  {
@@@ -1006,15 -928,27 +928,27 @@@
  
  	dw_hdmi_qp_bridge_clear_avi_infoframe(bridge);
  
- 	return dw_hdmi_qp_config_avi_infoframe(hdmi, buffer, len);
+ 	dw_hdmi_qp_write_infoframe(hdmi, buffer, len, PKT_AVI_CONTENTS0);
+ 
+ 	dw_hdmi_qp_mod(hdmi, 0, PKTSCHED_AVI_FIELDRATE, PKTSCHED_PKT_CONFIG1);
+ 	dw_hdmi_qp_mod(hdmi, PKTSCHED_AVI_TX_EN | PKTSCHED_GCP_TX_EN,
+ 		       PKTSCHED_AVI_TX_EN | PKTSCHED_GCP_TX_EN, PKTSCHED_PKT_EN);
+ 
+ 	return 0;
  }
  
  static int dw_hdmi_qp_bridge_write_hdmi_infoframe(struct drm_bridge *bridge,
  						  const u8 *buffer, size_t len)
  {
+ 	struct dw_hdmi_qp *hdmi = bridge->driver_private;
+ 
  	dw_hdmi_qp_bridge_clear_hdmi_infoframe(bridge);
  
- 	/* FIXME: add support for the HDMI VSI */
+ 	dw_hdmi_qp_write_infoframe(hdmi, buffer, len, PKT_VSI_CONTENTS0);
+ 
+ 	dw_hdmi_qp_mod(hdmi, 0, PKTSCHED_VSI_FIELDRATE, PKTSCHED_PKT_CONFIG1);
+ 	dw_hdmi_qp_mod(hdmi, PKTSCHED_VSI_TX_EN, PKTSCHED_VSI_TX_EN,
+ 		       PKTSCHED_PKT_EN);
  
  	return 0;
  }
@@@ -1026,7 -960,28 +960,28 @@@ static int dw_hdmi_qp_bridge_write_hdr_
  
  	dw_hdmi_qp_bridge_clear_hdr_drm_infoframe(bridge);
  
- 	return dw_hdmi_qp_config_drm_infoframe(hdmi, buffer, len);
+ 	dw_hdmi_qp_write_infoframe(hdmi, buffer, len, PKT_DRMI_CONTENTS0);
+ 
+ 	dw_hdmi_qp_mod(hdmi, 0, PKTSCHED_DRMI_FIELDRATE, PKTSCHED_PKT_CONFIG1);
+ 	dw_hdmi_qp_mod(hdmi, PKTSCHED_DRMI_TX_EN, PKTSCHED_DRMI_TX_EN,
+ 		       PKTSCHED_PKT_EN);
+ 
+ 	return 0;
+ }
+ 
+ static int dw_hdmi_qp_bridge_write_spd_infoframe(struct drm_bridge *bridge,
+ 						 const u8 *buffer, size_t len)
+ {
+ 	struct dw_hdmi_qp *hdmi = bridge->driver_private;
+ 
+ 	dw_hdmi_qp_bridge_clear_spd_infoframe(bridge);
+ 
+ 	dw_hdmi_qp_write_infoframe(hdmi, buffer, len, PKT_SPDI_CONTENTS0);
+ 
+ 	dw_hdmi_qp_mod(hdmi, PKTSCHED_SPDI_TX_EN, PKTSCHED_SPDI_TX_EN,
+ 		       PKTSCHED_PKT_EN);
+ 
+ 	return 0;
  }
  
  static int dw_hdmi_qp_bridge_write_audio_infoframe(struct drm_bridge *bridge,
@@@ -1036,7 -991,31 +991,31 @@@
  
  	dw_hdmi_qp_bridge_clear_audio_infoframe(bridge);
  
- 	return dw_hdmi_qp_config_audio_infoframe(hdmi, buffer, len);
+ 	/*
+ 	 * AUDI_CONTENTS0: { RSV, HB2, HB1, RSV }
+ 	 * AUDI_CONTENTS1: { PB3, PB2, PB1, PB0 }
+ 	 * AUDI_CONTENTS2: { PB7, PB6, PB5, PB4 }
+ 	 *
+ 	 * PB0: CheckSum
+ 	 * PB1: | CT3    | CT2  | CT1  | CT0  | F13  | CC2 | CC1 | CC0 |
+ 	 * PB2: | F27    | F26  | F25  | SF2  | SF1  | SF0 | SS1 | SS0 |
+ 	 * PB3: | F37    | F36  | F35  | F34  | F33  | F32 | F31 | F30 |
+ 	 * PB4: | CA7    | CA6  | CA5  | CA4  | CA3  | CA2 | CA1 | CA0 |
+ 	 * PB5: | DM_INH | LSV3 | LSV2 | LSV1 | LSV0 | F52 | F51 | F50 |
+ 	 * PB6~PB10: Reserved
+ 	 */
+ 	dw_hdmi_qp_write_infoframe(hdmi, buffer, len, PKT_AUDI_CONTENTS0);
+ 
+ 	/* Enable ACR, AUDI, AMD */
+ 	dw_hdmi_qp_mod(hdmi,
+ 		       PKTSCHED_ACR_TX_EN | PKTSCHED_AUDI_TX_EN | PKTSCHED_AMD_TX_EN,
+ 		       PKTSCHED_ACR_TX_EN | PKTSCHED_AUDI_TX_EN | PKTSCHED_AMD_TX_EN,
+ 		       PKTSCHED_PKT_EN);
+ 
+ 	/* Enable AUDS */
+ 	dw_hdmi_qp_mod(hdmi, PKTSCHED_AUDS_TX_EN, PKTSCHED_AUDS_TX_EN, PKTSCHED_PKT_EN);
+ 
+ 	return 0;
  }
  
  #ifdef CONFIG_DRM_DW_HDMI_QP_CEC
@@@ -1227,6 -1206,8 +1206,8 @@@ static const struct drm_bridge_funcs dw
  	.hdmi_write_hdmi_infoframe = dw_hdmi_qp_bridge_write_hdmi_infoframe,
  	.hdmi_clear_hdr_drm_infoframe = dw_hdmi_qp_bridge_clear_hdr_drm_infoframe,
  	.hdmi_write_hdr_drm_infoframe = dw_hdmi_qp_bridge_write_hdr_drm_infoframe,
+ 	.hdmi_clear_spd_infoframe = dw_hdmi_qp_bridge_clear_spd_infoframe,
+ 	.hdmi_write_spd_infoframe = dw_hdmi_qp_bridge_write_spd_infoframe,
  	.hdmi_clear_audio_infoframe = dw_hdmi_qp_bridge_clear_audio_infoframe,
  	.hdmi_write_audio_infoframe = dw_hdmi_qp_bridge_write_audio_infoframe,
  	.hdmi_audio_startup = dw_hdmi_qp_audio_enable,
@@@ -1344,7 -1325,8 +1325,8 @@@ struct dw_hdmi_qp *dw_hdmi_qp_bind(stru
  			   DRM_BRIDGE_OP_EDID |
  			   DRM_BRIDGE_OP_HDMI |
  			   DRM_BRIDGE_OP_HDMI_AUDIO |
- 			   DRM_BRIDGE_OP_HDMI_HDR_DRM_INFOFRAME;
+ 			   DRM_BRIDGE_OP_HDMI_HDR_DRM_INFOFRAME |
+ 			   DRM_BRIDGE_OP_HDMI_SPD_INFOFRAME;
  	if (!hdmi->no_hpd)
  		hdmi->bridge.ops |= DRM_BRIDGE_OP_HPD;
  	hdmi->bridge.of_node = pdev->dev.of_node;

Hello Mark, all,

On Wed Mar 18, 2026 at 3:36 PM CET, Mark Brown wrote:
> Hi all,
>
> Today's linux-next merge of the drm tree got a conflict in:
>
>   drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
>
> between commit:
>
>   cffcb42c57686 ("drm/bridge: dw-hdmi-qp: fix multi-channel audio output")
>
> from the drm-misc-fixes tree and commit:
>
>   3ea699b56d31c ("drm/bridge: dw-hdmi-qp: Rework Audio InfoFrame handler")
>
> from the drm tree.
>
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.

The conflict originated as I applied cffcb42c57686 on drm-misc-fixes. I
carefully followed the dim procedure as I know it, so I'm not sure I did
anything wrong, but if I did I apologize.

The steps I did are:

 - dim update-branches
 - dim checkout drm-misc-fixes
 - dim b4-shazam URL
 - dim checkpatch+sparse ...
 - dim push-branch drm-misc-fixes

One thing with this procedure is that dim push-branch pushes first, then
finds out any conflicts. I wonder whether dim could be changed to find any
conflicts before pushing.

As soon as dim push-branch warned me about the conflict I tried solving it
myself as per [0], but the patches on drm-misc-next (3ea699b56d31c) changed
the codebase completely and was unable to sort it out fully.

I at least fixed the conflict at a pure patch application level, so I would
expect the rerere cache would avoid future conflicts.  I was wrong
apparently. It had worked in the past, no idea what went wrong this time.

Then, as far as the original bug is concerned, I notified the involved
patch authors [1] hoping they could find out whether there is the same bug
in the drm-misc-next code and fix it if needed.

If there is anything I should have done differently I'd be happy to know in
order to adjust my process in the future.

[0] https://drm.pages.freedesktop.org/maintainer-tools/committer/conflict-resolution.html
[1] https://lore.kernel.org/lkml/DH58MAETGDMM.2QS6VJDQ7UXIV@bootlin.com/

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Hi Luca,

On 3/18/26 5:49 PM, Luca Ceresoli wrote:
> Hello Mark, all,
> 
> On Wed Mar 18, 2026 at 3:36 PM CET, Mark Brown wrote:
>> Hi all,
>>
>> Today's linux-next merge of the drm tree got a conflict in:
>>
>>   drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
>>
>> between commit:
>>
>>   cffcb42c57686 ("drm/bridge: dw-hdmi-qp: fix multi-channel audio output")
>>
>> from the drm-misc-fixes tree and commit:
>>
>>   3ea699b56d31c ("drm/bridge: dw-hdmi-qp: Rework Audio InfoFrame handler")
>>
>> from the drm tree.
>>
>> I fixed it up (see below) and can carry the fix as necessary. This
>> is now fixed as far as linux-next is concerned, but any non trivial
>> conflicts should be mentioned to your upstream maintainer when your tree
>> is submitted for merging.  You may also want to consider cooperating
>> with the maintainer of the conflicting tree to minimise any particularly
>> complex conflicts.
> 
> The conflict originated as I applied cffcb42c57686 on drm-misc-fixes. I
> carefully followed the dim procedure as I know it, so I'm not sure I did
> anything wrong, but if I did I apologize.
> 
> The steps I did are:
> 
>  - dim update-branches
>  - dim checkout drm-misc-fixes
>  - dim b4-shazam URL
>  - dim checkpatch+sparse ...
>  - dim push-branch drm-misc-fixes
> 
> One thing with this procedure is that dim push-branch pushes first, then
> finds out any conflicts. I wonder whether dim could be changed to find any
> conflicts before pushing.
> 
> As soon as dim push-branch warned me about the conflict I tried solving it
> myself as per [0], but the patches on drm-misc-next (3ea699b56d31c) changed
> the codebase completely and was unable to sort it out fully.
> 
> I at least fixed the conflict at a pure patch application level, so I would
> expect the rerere cache would avoid future conflicts.  I was wrong
> apparently. It had worked in the past, no idea what went wrong this time.
> 
> Then, as far as the original bug is concerned, I notified the involved
> patch authors [1] hoping they could find out whether there is the same bug
> in the drm-misc-next code and fix it if needed.

I've already confirmed that commit 3ea699b56d31c in drm-misc-next does also
handle the audio bug, therefore no additional fix is required.

Regards,
Cristian