diff mbox series

[PATCHv3] drm/i915/display/dp: On AUX xfer timeout restart freshly

Message ID 20230613044239.691706-1-arun.r.murthy@intel.com (mailing list archive)
State New, archived
Headers show
Series [PATCHv3] drm/i915/display/dp: On AUX xfer timeout restart freshly | expand

Commit Message

Murthy, Arun R June 13, 2023, 4:42 a.m. UTC
On AUX transfer timeout, as per DP spec need to retry for 3 times and
has to be restarted freshly.

v3: handle timeout and dont rely on register value on timeout (Imre)

Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
---
 .../drm/i915/display/intel_display_types.h    |  1 -
 drivers/gpu/drm/i915/display/intel_dp_aux.c   | 72 +++++++++----------
 2 files changed, 34 insertions(+), 39 deletions(-)

Comments

Imre Deak June 13, 2023, 10:49 a.m. UTC | #1
On Tue, Jun 13, 2023 at 10:12:39AM +0530, Arun R Murthy wrote:
> On AUX transfer timeout, as per DP spec need to retry for 3 times and
> has to be restarted freshly.
> 
> v3: handle timeout and dont rely on register value on timeout (Imre)
> 
> Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
> ---
>  .../drm/i915/display/intel_display_types.h    |  1 -
>  drivers/gpu/drm/i915/display/intel_dp_aux.c   | 72 +++++++++----------
>  2 files changed, 34 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 2d8297f8d088..0942b109b4ca 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1741,7 +1741,6 @@ struct intel_dp {
>  	/* sink or branch descriptor */
>  	struct drm_dp_desc desc;
>  	struct drm_dp_aux aux;
> -	u32 aux_busy_last_status;
>  	u8 train_set[4];
>  
>  	struct intel_pps pps;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> index 0c27db8ae4f1..244b4d7d716d 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> @@ -36,25 +36,24 @@ static void intel_dp_aux_unpack(u32 src, u8 *dst, int dst_bytes)
>  		dst[i] = src >> ((3 - i) * 8);
>  }
>  
> -static u32
> -intel_dp_aux_wait_done(struct intel_dp *intel_dp)
> +static int
> +intel_dp_aux_wait_done(struct intel_dp *intel_dp, u32 *status)
>  {
>  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
>  	i915_reg_t ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp);
>  	const unsigned int timeout_ms = 10;
> -	u32 status;
>  	int ret;
>  
>  	ret = __intel_de_wait_for_register(i915, ch_ctl,
>  					   DP_AUX_CH_CTL_SEND_BUSY, 0,
> -					   2, timeout_ms, &status);
> +					   50, timeout_ms, status);
>  
>  	if (ret == -ETIMEDOUT)
>  		drm_err(&i915->drm,
>  			"%s: did not complete or timeout within %ums (status 0x%08x)\n",
> -			intel_dp->aux.name, timeout_ms, status);
> +			intel_dp->aux.name, timeout_ms, *status);
>  
> -	return status;
> +	return ret;
>  }
>  
>  static u32 g4x_get_aux_clock_divider(struct intel_dp *intel_dp, int index)
> @@ -186,10 +185,7 @@ static u32 skl_get_aux_send_ctl(struct intel_dp *intel_dp,
>  	 */
>  	ret = DP_AUX_CH_CTL_SEND_BUSY |
>  		DP_AUX_CH_CTL_DONE |
> -		DP_AUX_CH_CTL_INTERRUPT |

The above one-liner change, also applied in g4x_get_aux_send_ctl()
should be a separate patch.

> -		DP_AUX_CH_CTL_TIME_OUT_ERROR |
>  		DP_AUX_CH_CTL_TIME_OUT_MAX |
> -		DP_AUX_CH_CTL_RECEIVE_ERROR |
>  		DP_AUX_CH_CTL_MESSAGE_SIZE(send_bytes) |
>  		DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(intel_dp_aux_fw_sync_len()) |
>  		DP_AUX_CH_CTL_SYNC_PULSE_SKL(intel_dp_aux_sync_len());
> @@ -273,30 +269,6 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
>  	 * it using the same AUX CH simultaneously
>  	 */
>  
> -	/* Try to wait for any previous AUX channel activity */
> -	for (try = 0; try < 3; try++) {
> -		status = intel_de_read_notrace(i915, ch_ctl);
> -		if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0)
> -			break;
> -		msleep(1);
> -	}
> -	/* just trace the final value */
> -	trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
> -
> -	if (try == 3) {
> -		const u32 status = intel_de_read(i915, ch_ctl);
> -
> -		if (status != intel_dp->aux_busy_last_status) {
> -			drm_WARN(&i915->drm, 1,
> -				 "%s: not started (status 0x%08x)\n",
> -				 intel_dp->aux.name, status);
> -			intel_dp->aux_busy_last_status = status;
> -		}
> -
> -		ret = -EBUSY;
> -		goto out;
> -	}
> -
>  	/* Only 5 data registers! */
>  	if (drm_WARN_ON(&i915->drm, send_bytes > 20 || recv_size > 20)) {
>  		ret = -E2BIG;
> @@ -304,14 +276,31 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
>  	}
>  
>  	while ((aux_clock_divider = intel_dp->get_aux_clock_divider(intel_dp, clock++))) {
> -		u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
> +		/* Must try at least 3 times according to DP spec */
> +		for (try = 0; try < 5; try++) {
> +			u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
>  							  send_bytes,
>  							  aux_clock_divider);
>  
> -		send_ctl |= aux_send_ctl_flags;
> +			send_ctl |= aux_send_ctl_flags;
> +
> +			/* Try to wait for any previous AUX channel activity */
> +			/* TODO: if typeC then 4.2ms else 800us. For DG2 add 1.5ms for both cases */
> +			ret = intel_dp_aux_wait_done(intel_dp, &status);
> +			/* just trace the final value */
> +			trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
> +
> +			/* On timeout dont read the status bits as its not updated */
> +			if (ret == -ETIMEDOUT) {
> +				drm_WARN(&i915->drm, 1,
> +					 "%s: not started, previous Tx still in process (status 0x%08x)\n",
> +					 intel_dp->aux.name, status);
> +				if (try > 3)
> +					goto out;
> +				else
> +					continue;
> +			}
>  
> -		/* Must try at least 3 times according to DP spec */
> -		for (try = 0; try < 5; try++) {
>  			/* Load the send data into the aux channel data registers */
>  			for (i = 0; i < send_bytes; i += 4)
>  				intel_de_write(i915, ch_data[i >> 2],
> @@ -320,8 +309,15 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
>  
>  			/* Send the command and wait for it to complete */
>  			intel_de_write(i915, ch_ctl, send_ctl);
> +			intel_de_rmw(i915, ch_ctl, DP_AUX_CH_CTL_INTERRUPT |
> +				     DP_AUX_CH_CTL_TIME_OUT_ERROR |
> +				     DP_AUX_CH_CTL_RECEIVE_ERROR, 0);
>  
> -			status = intel_dp_aux_wait_done(intel_dp);

The review comments were not addressed and these changes still don't
make sense to me. What I meant is - instead of all the above changes -
bailing out at this point if DP_AUX_CH_CTL_SEND_BUSY is still set in
status.

> +			ret = intel_dp_aux_wait_done(intel_dp, &status);
> +
> +			/* On timeout dont read the status bits as its not updated */
> +			if (ret == -ETIMEDOUT)
> +				continue;
>  
>  			/* Clear done status and any errors */
>  			intel_de_write(i915, ch_ctl,
> -- 
> 2.25.1
>
Kahola, Mika June 13, 2023, 12:31 p.m. UTC | #2
> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of Arun R Murthy
> Sent: Tuesday, June 13, 2023 7:43 AM
> To: intel-gfx@lists.freedesktop.org
> Cc: Nikula, Jani <jani.nikula@intel.com>
> Subject: [Intel-gfx] [PATCHv3] drm/i915/display/dp: On AUX xfer timeout restart freshly
> 
> On AUX transfer timeout, as per DP spec need to retry for 3 times and has to be restarted freshly.
> 
> v3: handle timeout and dont rely on register value on timeout (Imre)
> 
> Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
> ---
>  .../drm/i915/display/intel_display_types.h    |  1 -
>  drivers/gpu/drm/i915/display/intel_dp_aux.c   | 72 +++++++++----------
>  2 files changed, 34 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 2d8297f8d088..0942b109b4ca 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1741,7 +1741,6 @@ struct intel_dp {
>  	/* sink or branch descriptor */
>  	struct drm_dp_desc desc;
>  	struct drm_dp_aux aux;
> -	u32 aux_busy_last_status;
>  	u8 train_set[4];
> 
>  	struct intel_pps pps;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> index 0c27db8ae4f1..244b4d7d716d 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> @@ -36,25 +36,24 @@ static void intel_dp_aux_unpack(u32 src, u8 *dst, int dst_bytes)
>  		dst[i] = src >> ((3 - i) * 8);
>  }
> 
> -static u32
> -intel_dp_aux_wait_done(struct intel_dp *intel_dp)
> +static int
> +intel_dp_aux_wait_done(struct intel_dp *intel_dp, u32 *status)
>  {
>  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
>  	i915_reg_t ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp);
>  	const unsigned int timeout_ms = 10;
> -	u32 status;
>  	int ret;
> 
>  	ret = __intel_de_wait_for_register(i915, ch_ctl,
>  					   DP_AUX_CH_CTL_SEND_BUSY, 0,
> -					   2, timeout_ms, &status);
> +					   50, timeout_ms, status);
> 
>  	if (ret == -ETIMEDOUT)
>  		drm_err(&i915->drm,
>  			"%s: did not complete or timeout within %ums (status 0x%08x)\n",
> -			intel_dp->aux.name, timeout_ms, status);
> +			intel_dp->aux.name, timeout_ms, *status);
> 
> -	return status;
> +	return ret;
>  }
> 
>  static u32 g4x_get_aux_clock_divider(struct intel_dp *intel_dp, int index) @@ -186,10 +185,7 @@ static u32
> skl_get_aux_send_ctl(struct intel_dp *intel_dp,
>  	 */
>  	ret = DP_AUX_CH_CTL_SEND_BUSY |
>  		DP_AUX_CH_CTL_DONE |
> -		DP_AUX_CH_CTL_INTERRUPT |
> -		DP_AUX_CH_CTL_TIME_OUT_ERROR |
>  		DP_AUX_CH_CTL_TIME_OUT_MAX |
> -		DP_AUX_CH_CTL_RECEIVE_ERROR |
>  		DP_AUX_CH_CTL_MESSAGE_SIZE(send_bytes) |
>  		DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(intel_dp_aux_fw_sync_len()) |
>  		DP_AUX_CH_CTL_SYNC_PULSE_SKL(intel_dp_aux_sync_len());
> @@ -273,30 +269,6 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
>  	 * it using the same AUX CH simultaneously
>  	 */
> 
> -	/* Try to wait for any previous AUX channel activity */
> -	for (try = 0; try < 3; try++) {
> -		status = intel_de_read_notrace(i915, ch_ctl);
> -		if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0)
> -			break;
> -		msleep(1);
> -	}
> -	/* just trace the final value */
> -	trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
> -
> -	if (try == 3) {
> -		const u32 status = intel_de_read(i915, ch_ctl);
> -
> -		if (status != intel_dp->aux_busy_last_status) {
> -			drm_WARN(&i915->drm, 1,
> -				 "%s: not started (status 0x%08x)\n",
> -				 intel_dp->aux.name, status);
> -			intel_dp->aux_busy_last_status = status;
> -		}
> -
> -		ret = -EBUSY;
> -		goto out;
> -	}
> -
>  	/* Only 5 data registers! */
>  	if (drm_WARN_ON(&i915->drm, send_bytes > 20 || recv_size > 20)) {
>  		ret = -E2BIG;
> @@ -304,14 +276,31 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
>  	}
> 
>  	while ((aux_clock_divider = intel_dp->get_aux_clock_divider(intel_dp, clock++))) {
> -		u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
> +		/* Must try at least 3 times according to DP spec */
> +		for (try = 0; try < 5; try++) {
It seems that we try 5 times here. Was this intention or keep tries in 3 as commit message/comment would suggest?

-Mika-
> +			u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
>  							  send_bytes,
>  							  aux_clock_divider);
> 
> -		send_ctl |= aux_send_ctl_flags;
> +			send_ctl |= aux_send_ctl_flags;
> +
> +			/* Try to wait for any previous AUX channel activity */
> +			/* TODO: if typeC then 4.2ms else 800us. For DG2 add 1.5ms for both cases */
> +			ret = intel_dp_aux_wait_done(intel_dp, &status);
> +			/* just trace the final value */
> +			trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
> +
> +			/* On timeout dont read the status bits as its not updated */
> +			if (ret == -ETIMEDOUT) {
> +				drm_WARN(&i915->drm, 1,
> +					 "%s: not started, previous Tx still in process (status 0x%08x)\n",
> +					 intel_dp->aux.name, status);
> +				if (try > 3)
> +					goto out;
> +				else
> +					continue;
> +			}
> 
> -		/* Must try at least 3 times according to DP spec */
> -		for (try = 0; try < 5; try++) {
>  			/* Load the send data into the aux channel data registers */
>  			for (i = 0; i < send_bytes; i += 4)
>  				intel_de_write(i915, ch_data[i >> 2], @@ -320,8 +309,15 @@ intel_dp_aux_xfer(struct
> intel_dp *intel_dp,
> 
>  			/* Send the command and wait for it to complete */
>  			intel_de_write(i915, ch_ctl, send_ctl);
> +			intel_de_rmw(i915, ch_ctl, DP_AUX_CH_CTL_INTERRUPT |
> +				     DP_AUX_CH_CTL_TIME_OUT_ERROR |
> +				     DP_AUX_CH_CTL_RECEIVE_ERROR, 0);
> 
> -			status = intel_dp_aux_wait_done(intel_dp);
> +			ret = intel_dp_aux_wait_done(intel_dp, &status);
> +
> +			/* On timeout dont read the status bits as its not updated */
> +			if (ret == -ETIMEDOUT)
> +				continue;
> 
>  			/* Clear done status and any errors */
>  			intel_de_write(i915, ch_ctl,
> --
> 2.25.1
Murthy, Arun R June 19, 2023, 6:24 a.m. UTC | #3
> -----Original Message-----
> From: Kahola, Mika <mika.kahola@intel.com>
> Sent: Tuesday, June 13, 2023 6:02 PM
> To: Murthy, Arun R <arun.r.murthy@intel.com>; intel-
> gfx@lists.freedesktop.org
> Cc: Nikula, Jani <jani.nikula@intel.com>
> Subject: RE: [Intel-gfx] [PATCHv3] drm/i915/display/dp: On AUX xfer timeout
> restart freshly
> 
> > -----Original Message-----
> > From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of
> > Arun R Murthy
> > Sent: Tuesday, June 13, 2023 7:43 AM
> > To: intel-gfx@lists.freedesktop.org
> > Cc: Nikula, Jani <jani.nikula@intel.com>
> > Subject: [Intel-gfx] [PATCHv3] drm/i915/display/dp: On AUX xfer
> > timeout restart freshly
> >
> > On AUX transfer timeout, as per DP spec need to retry for 3 times and has
> to be restarted freshly.
> >
> > v3: handle timeout and dont rely on register value on timeout (Imre)
> >
> > Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
> > ---
> >  .../drm/i915/display/intel_display_types.h    |  1 -
> >  drivers/gpu/drm/i915/display/intel_dp_aux.c   | 72 +++++++++----------
> >  2 files changed, 34 insertions(+), 39 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> > b/drivers/gpu/drm/i915/display/intel_display_types.h
> > index 2d8297f8d088..0942b109b4ca 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > @@ -1741,7 +1741,6 @@ struct intel_dp {
> >  	/* sink or branch descriptor */
> >  	struct drm_dp_desc desc;
> >  	struct drm_dp_aux aux;
> > -	u32 aux_busy_last_status;
> >  	u8 train_set[4];
> >
> >  	struct intel_pps pps;
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > index 0c27db8ae4f1..244b4d7d716d 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > @@ -36,25 +36,24 @@ static void intel_dp_aux_unpack(u32 src, u8 *dst,
> int dst_bytes)
> >  		dst[i] = src >> ((3 - i) * 8);
> >  }
> >
> > -static u32
> > -intel_dp_aux_wait_done(struct intel_dp *intel_dp)
> > +static int
> > +intel_dp_aux_wait_done(struct intel_dp *intel_dp, u32 *status)
> >  {
> >  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> >  	i915_reg_t ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp);
> >  	const unsigned int timeout_ms = 10;
> > -	u32 status;
> >  	int ret;
> >
> >  	ret = __intel_de_wait_for_register(i915, ch_ctl,
> >  					   DP_AUX_CH_CTL_SEND_BUSY, 0,
> > -					   2, timeout_ms, &status);
> > +					   50, timeout_ms, status);
> >
> >  	if (ret == -ETIMEDOUT)
> >  		drm_err(&i915->drm,
> >  			"%s: did not complete or timeout within %ums
> (status 0x%08x)\n",
> > -			intel_dp->aux.name, timeout_ms, status);
> > +			intel_dp->aux.name, timeout_ms, *status);
> >
> > -	return status;
> > +	return ret;
> >  }
> >
> >  static u32 g4x_get_aux_clock_divider(struct intel_dp *intel_dp, int
> > index) @@ -186,10 +185,7 @@ static u32 skl_get_aux_send_ctl(struct
> intel_dp *intel_dp,
> >  	 */
> >  	ret = DP_AUX_CH_CTL_SEND_BUSY |
> >  		DP_AUX_CH_CTL_DONE |
> > -		DP_AUX_CH_CTL_INTERRUPT |
> > -		DP_AUX_CH_CTL_TIME_OUT_ERROR |
> >  		DP_AUX_CH_CTL_TIME_OUT_MAX |
> > -		DP_AUX_CH_CTL_RECEIVE_ERROR |
> >  		DP_AUX_CH_CTL_MESSAGE_SIZE(send_bytes) |
> >
> 	DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(intel_dp_aux_fw_sync_len())
> |
> >
> 	DP_AUX_CH_CTL_SYNC_PULSE_SKL(intel_dp_aux_sync_len());
> > @@ -273,30 +269,6 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> >  	 * it using the same AUX CH simultaneously
> >  	 */
> >
> > -	/* Try to wait for any previous AUX channel activity */
> > -	for (try = 0; try < 3; try++) {
> > -		status = intel_de_read_notrace(i915, ch_ctl);
> > -		if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0)
> > -			break;
> > -		msleep(1);
> > -	}
> > -	/* just trace the final value */
> > -	trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
> > -
> > -	if (try == 3) {
> > -		const u32 status = intel_de_read(i915, ch_ctl);
> > -
> > -		if (status != intel_dp->aux_busy_last_status) {
> > -			drm_WARN(&i915->drm, 1,
> > -				 "%s: not started (status 0x%08x)\n",
> > -				 intel_dp->aux.name, status);
> > -			intel_dp->aux_busy_last_status = status;
> > -		}
> > -
> > -		ret = -EBUSY;
> > -		goto out;
> > -	}
> > -
> >  	/* Only 5 data registers! */
> >  	if (drm_WARN_ON(&i915->drm, send_bytes > 20 || recv_size > 20)) {
> >  		ret = -E2BIG;
> > @@ -304,14 +276,31 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> >  	}
> >
> >  	while ((aux_clock_divider = intel_dp-
> >get_aux_clock_divider(intel_dp, clock++))) {
> > -		u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
> > +		/* Must try at least 3 times according to DP spec */
> > +		for (try = 0; try < 5; try++) {
> It seems that we try 5 times here. Was this intention or keep tries in 3 as
> commit message/comment would suggest?
> 
Will change the comment. As per the spec yes its 3 times, but with software overhead we have been trying this retry for 5 times.

Thanks and Regards,
Arun R Murthy
--------------------
> -Mika-
> > +			u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
> >  							  send_bytes,
> >  							  aux_clock_divider);
> >
> > -		send_ctl |= aux_send_ctl_flags;
> > +			send_ctl |= aux_send_ctl_flags;
> > +
> > +			/* Try to wait for any previous AUX channel activity
> */
> > +			/* TODO: if typeC then 4.2ms else 800us. For DG2
> add 1.5ms for both cases */
> > +			ret = intel_dp_aux_wait_done(intel_dp, &status);
> > +			/* just trace the final value */
> > +			trace_i915_reg_rw(false, ch_ctl, status, sizeof(status),
> true);
> > +
> > +			/* On timeout dont read the status bits as its not
> updated */
> > +			if (ret == -ETIMEDOUT) {
> > +				drm_WARN(&i915->drm, 1,
> > +					 "%s: not started, previous Tx still in
> process (status 0x%08x)\n",
> > +					 intel_dp->aux.name, status);
> > +				if (try > 3)
> > +					goto out;
> > +				else
> > +					continue;
> > +			}
> >
> > -		/* Must try at least 3 times according to DP spec */
> > -		for (try = 0; try < 5; try++) {
> >  			/* Load the send data into the aux channel data
> registers */
> >  			for (i = 0; i < send_bytes; i += 4)
> >  				intel_de_write(i915, ch_data[i >> 2], @@ -
> 320,8 +309,15 @@
> > intel_dp_aux_xfer(struct intel_dp *intel_dp,
> >
> >  			/* Send the command and wait for it to complete */
> >  			intel_de_write(i915, ch_ctl, send_ctl);
> > +			intel_de_rmw(i915, ch_ctl,
> DP_AUX_CH_CTL_INTERRUPT |
> > +				     DP_AUX_CH_CTL_TIME_OUT_ERROR |
> > +				     DP_AUX_CH_CTL_RECEIVE_ERROR, 0);
> >
> > -			status = intel_dp_aux_wait_done(intel_dp);
> > +			ret = intel_dp_aux_wait_done(intel_dp, &status);
> > +
> > +			/* On timeout dont read the status bits as its not
> updated */
> > +			if (ret == -ETIMEDOUT)
> > +				continue;
> >
> >  			/* Clear done status and any errors */
> >  			intel_de_write(i915, ch_ctl,
> > --
> > 2.25.1
Murthy, Arun R June 20, 2023, 6:26 a.m. UTC | #4
> -----Original Message-----
> From: Deak, Imre <imre.deak@intel.com>
> Sent: Tuesday, June 13, 2023 4:19 PM
> To: Murthy, Arun R <arun.r.murthy@intel.com>
> Cc: intel-gfx@lists.freedesktop.org; Nikula, Jani <jani.nikula@intel.com>
> Subject: Re: [PATCHv3] drm/i915/display/dp: On AUX xfer timeout restart
> freshly
> 
> On Tue, Jun 13, 2023 at 10:12:39AM +0530, Arun R Murthy wrote:
> > On AUX transfer timeout, as per DP spec need to retry for 3 times and
> > has to be restarted freshly.
> >
> > v3: handle timeout and dont rely on register value on timeout (Imre)
> >
> > Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
> > ---
> >  .../drm/i915/display/intel_display_types.h    |  1 -
> >  drivers/gpu/drm/i915/display/intel_dp_aux.c   | 72 +++++++++----------
> >  2 files changed, 34 insertions(+), 39 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> > b/drivers/gpu/drm/i915/display/intel_display_types.h
> > index 2d8297f8d088..0942b109b4ca 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > @@ -1741,7 +1741,6 @@ struct intel_dp {
> >  	/* sink or branch descriptor */
> >  	struct drm_dp_desc desc;
> >  	struct drm_dp_aux aux;
> > -	u32 aux_busy_last_status;
> >  	u8 train_set[4];
> >
> >  	struct intel_pps pps;
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > index 0c27db8ae4f1..244b4d7d716d 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > @@ -36,25 +36,24 @@ static void intel_dp_aux_unpack(u32 src, u8 *dst,
> int dst_bytes)
> >  		dst[i] = src >> ((3 - i) * 8);
> >  }
> >
> > -static u32
> > -intel_dp_aux_wait_done(struct intel_dp *intel_dp)
> > +static int
> > +intel_dp_aux_wait_done(struct intel_dp *intel_dp, u32 *status)
> >  {
> >  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> >  	i915_reg_t ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp);
> >  	const unsigned int timeout_ms = 10;
> > -	u32 status;
> >  	int ret;
> >
> >  	ret = __intel_de_wait_for_register(i915, ch_ctl,
> >  					   DP_AUX_CH_CTL_SEND_BUSY, 0,
> > -					   2, timeout_ms, &status);
> > +					   50, timeout_ms, status);
> >
> >  	if (ret == -ETIMEDOUT)
> >  		drm_err(&i915->drm,
> >  			"%s: did not complete or timeout within %ums
> (status 0x%08x)\n",
> > -			intel_dp->aux.name, timeout_ms, status);
> > +			intel_dp->aux.name, timeout_ms, *status);
> >
> > -	return status;
> > +	return ret;
> >  }
> >
> >  static u32 g4x_get_aux_clock_divider(struct intel_dp *intel_dp, int
> > index) @@ -186,10 +185,7 @@ static u32 skl_get_aux_send_ctl(struct
> intel_dp *intel_dp,
> >  	 */
> >  	ret = DP_AUX_CH_CTL_SEND_BUSY |
> >  		DP_AUX_CH_CTL_DONE |
> > -		DP_AUX_CH_CTL_INTERRUPT |
> 
> The above one-liner change, also applied in g4x_get_aux_send_ctl() should
> be a separate patch.
> 
> > -		DP_AUX_CH_CTL_TIME_OUT_ERROR |
> >  		DP_AUX_CH_CTL_TIME_OUT_MAX |
> > -		DP_AUX_CH_CTL_RECEIVE_ERROR |
> >  		DP_AUX_CH_CTL_MESSAGE_SIZE(send_bytes) |
> >
> 	DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(intel_dp_aux_fw_sync_len())
> |
> >
> 	DP_AUX_CH_CTL_SYNC_PULSE_SKL(intel_dp_aux_sync_len());
> > @@ -273,30 +269,6 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> >  	 * it using the same AUX CH simultaneously
> >  	 */
> >
> > -	/* Try to wait for any previous AUX channel activity */
> > -	for (try = 0; try < 3; try++) {
> > -		status = intel_de_read_notrace(i915, ch_ctl);
> > -		if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0)
> > -			break;
> > -		msleep(1);
> > -	}
> > -	/* just trace the final value */
> > -	trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
> > -
> > -	if (try == 3) {
> > -		const u32 status = intel_de_read(i915, ch_ctl);
> > -
> > -		if (status != intel_dp->aux_busy_last_status) {
> > -			drm_WARN(&i915->drm, 1,
> > -				 "%s: not started (status 0x%08x)\n",
> > -				 intel_dp->aux.name, status);
> > -			intel_dp->aux_busy_last_status = status;
> > -		}
> > -
> > -		ret = -EBUSY;
> > -		goto out;
> > -	}
> > -
> >  	/* Only 5 data registers! */
> >  	if (drm_WARN_ON(&i915->drm, send_bytes > 20 || recv_size > 20)) {
> >  		ret = -E2BIG;
> > @@ -304,14 +276,31 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> >  	}
> >
> >  	while ((aux_clock_divider = intel_dp-
> >get_aux_clock_divider(intel_dp, clock++))) {
> > -		u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
> > +		/* Must try at least 3 times according to DP spec */
> > +		for (try = 0; try < 5; try++) {
> > +			u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
> >  							  send_bytes,
> >  							  aux_clock_divider);
> >
> > -		send_ctl |= aux_send_ctl_flags;
> > +			send_ctl |= aux_send_ctl_flags;
> > +
> > +			/* Try to wait for any previous AUX channel activity
> */
> > +			/* TODO: if typeC then 4.2ms else 800us. For DG2
> add 1.5ms for both cases */
> > +			ret = intel_dp_aux_wait_done(intel_dp, &status);
> > +			/* just trace the final value */
> > +			trace_i915_reg_rw(false, ch_ctl, status, sizeof(status),
> true);
> > +
> > +			/* On timeout dont read the status bits as its not
> updated */
> > +			if (ret == -ETIMEDOUT) {
> > +				drm_WARN(&i915->drm, 1,
> > +					 "%s: not started, previous Tx still in
> process (status 0x%08x)\n",
> > +					 intel_dp->aux.name, status);
> > +				if (try > 3)
> > +					goto out;
> > +				else
> > +					continue;
> > +			}
> >
> > -		/* Must try at least 3 times according to DP spec */
> > -		for (try = 0; try < 5; try++) {
> >  			/* Load the send data into the aux channel data
> registers */
> >  			for (i = 0; i < send_bytes; i += 4)
> >  				intel_de_write(i915, ch_data[i >> 2], @@ -
> 320,8 +309,15 @@
> > intel_dp_aux_xfer(struct intel_dp *intel_dp,
> >
> >  			/* Send the command and wait for it to complete */
> >  			intel_de_write(i915, ch_ctl, send_ctl);
> > +			intel_de_rmw(i915, ch_ctl,
> DP_AUX_CH_CTL_INTERRUPT |
> > +				     DP_AUX_CH_CTL_TIME_OUT_ERROR |
> > +				     DP_AUX_CH_CTL_RECEIVE_ERROR, 0);
> >
> > -			status = intel_dp_aux_wait_done(intel_dp);
> 
> The review comments were not addressed and these changes still don't
> make sense to me. What I meant is - instead of all the above changes -
> bailing out at this point if DP_AUX_CH_CTL_SEND_BUSY is still set in status.
> 

I think my 2st patch version had considered this SEND_BUSY bit. In the beginning of this loop there is a check for SEND_BUSY to ensure that the previous aux transaction is complete. Then we write the data and here we check for error(timeout or receive) only. If SEND_BUSY is checked over here again the code for aux transaction in progress check will be duplicated.

Will be floating v6 patch which takes care of this SEND_BUSY and acts upon properly.

Thanks and Regards,
Arun R Murthy
--------------------
Imre Deak June 20, 2023, 5:07 p.m. UTC | #5
On Tue, Jun 20, 2023 at 09:26:28AM +0300, Murthy, Arun R wrote:
> > -----Original Message-----
> > From: Deak, Imre <imre.deak@intel.com>
> > Sent: Tuesday, June 13, 2023 4:19 PM
> > To: Murthy, Arun R <arun.r.murthy@intel.com>
> > Cc: intel-gfx@lists.freedesktop.org; Nikula, Jani <jani.nikula@intel.com>
> > Subject: Re: [PATCHv3] drm/i915/display/dp: On AUX xfer timeout restart
> > freshly
> >
> > On Tue, Jun 13, 2023 at 10:12:39AM +0530, Arun R Murthy wrote:
> > > On AUX transfer timeout, as per DP spec need to retry for 3 times and
> > > has to be restarted freshly.
> > >
> > > v3: handle timeout and dont rely on register value on timeout (Imre)
> > >
> > > Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
> > > ---
> > >  .../drm/i915/display/intel_display_types.h    |  1 -
> > >  drivers/gpu/drm/i915/display/intel_dp_aux.c   | 72 +++++++++----------
> > >  2 files changed, 34 insertions(+), 39 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > index 2d8297f8d088..0942b109b4ca 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > @@ -1741,7 +1741,6 @@ struct intel_dp {
> > >     /* sink or branch descriptor */
> > >     struct drm_dp_desc desc;
> > >     struct drm_dp_aux aux;
> > > -   u32 aux_busy_last_status;
> > >     u8 train_set[4];
> > >
> > >     struct intel_pps pps;
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > > b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > > index 0c27db8ae4f1..244b4d7d716d 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> > > @@ -36,25 +36,24 @@ static void intel_dp_aux_unpack(u32 src, u8 *dst,
> > int dst_bytes)
> > >             dst[i] = src >> ((3 - i) * 8);
> > >  }
> > >
> > > -static u32
> > > -intel_dp_aux_wait_done(struct intel_dp *intel_dp)
> > > +static int
> > > +intel_dp_aux_wait_done(struct intel_dp *intel_dp, u32 *status)
> > >  {
> > >     struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > >     i915_reg_t ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp);
> > >     const unsigned int timeout_ms = 10;
> > > -   u32 status;
> > >     int ret;
> > >
> > >     ret = __intel_de_wait_for_register(i915, ch_ctl,
> > >                                        DP_AUX_CH_CTL_SEND_BUSY, 0,
> > > -                                      2, timeout_ms, &status);
> > > +                                      50, timeout_ms, status);
> > >
> > >     if (ret == -ETIMEDOUT)
> > >             drm_err(&i915->drm,
> > >                     "%s: did not complete or timeout within %ums
> > (status 0x%08x)\n",
> > > -                   intel_dp->aux.name, timeout_ms, status);
> > > +                   intel_dp->aux.name, timeout_ms, *status);
> > >
> > > -   return status;
> > > +   return ret;
> > >  }
> > >
> > >  static u32 g4x_get_aux_clock_divider(struct intel_dp *intel_dp, int
> > > index) @@ -186,10 +185,7 @@ static u32 skl_get_aux_send_ctl(struct
> > intel_dp *intel_dp,
> > >      */
> > >     ret = DP_AUX_CH_CTL_SEND_BUSY |
> > >             DP_AUX_CH_CTL_DONE |
> > > -           DP_AUX_CH_CTL_INTERRUPT |
> >
> > The above one-liner change, also applied in g4x_get_aux_send_ctl() should
> > be a separate patch.
> >
> > > -           DP_AUX_CH_CTL_TIME_OUT_ERROR |
> > >             DP_AUX_CH_CTL_TIME_OUT_MAX |
> > > -           DP_AUX_CH_CTL_RECEIVE_ERROR |
> > >             DP_AUX_CH_CTL_MESSAGE_SIZE(send_bytes) |
> > >
> >       DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(intel_dp_aux_fw_sync_len())
> > |
> > >
> >       DP_AUX_CH_CTL_SYNC_PULSE_SKL(intel_dp_aux_sync_len());
> > > @@ -273,30 +269,6 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> > >      * it using the same AUX CH simultaneously
> > >      */
> > >
> > > -   /* Try to wait for any previous AUX channel activity */
> > > -   for (try = 0; try < 3; try++) {
> > > -           status = intel_de_read_notrace(i915, ch_ctl);
> > > -           if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0)
> > > -                   break;
> > > -           msleep(1);
> > > -   }
> > > -   /* just trace the final value */
> > > -   trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
> > > -
> > > -   if (try == 3) {
> > > -           const u32 status = intel_de_read(i915, ch_ctl);
> > > -
> > > -           if (status != intel_dp->aux_busy_last_status) {
> > > -                   drm_WARN(&i915->drm, 1,
> > > -                            "%s: not started (status 0x%08x)\n",
> > > -                            intel_dp->aux.name, status);
> > > -                   intel_dp->aux_busy_last_status = status;
> > > -           }
> > > -
> > > -           ret = -EBUSY;
> > > -           goto out;
> > > -   }
> > > -
> > >     /* Only 5 data registers! */
> > >     if (drm_WARN_ON(&i915->drm, send_bytes > 20 || recv_size > 20)) {
> > >             ret = -E2BIG;
> > > @@ -304,14 +276,31 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> > >     }
> > >
> > >     while ((aux_clock_divider = intel_dp-
> > >get_aux_clock_divider(intel_dp, clock++))) {
> > > -           u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
> > > +           /* Must try at least 3 times according to DP spec */
> > > +           for (try = 0; try < 5; try++) {
> > > +                   u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
> > >                                                       send_bytes,
> > >                                                       aux_clock_divider);
> > >
> > > -           send_ctl |= aux_send_ctl_flags;
> > > +                   send_ctl |= aux_send_ctl_flags;
> > > +
> > > +                   /* Try to wait for any previous AUX channel activity
> > */
> > > +                   /* TODO: if typeC then 4.2ms else 800us. For DG2
> > add 1.5ms for both cases */
> > > +                   ret = intel_dp_aux_wait_done(intel_dp, &status);
> > > +                   /* just trace the final value */
> > > +                   trace_i915_reg_rw(false, ch_ctl, status, sizeof(status),
> > true);
> > > +
> > > +                   /* On timeout dont read the status bits as its not
> > updated */
> > > +                   if (ret == -ETIMEDOUT) {
> > > +                           drm_WARN(&i915->drm, 1,
> > > +                                    "%s: not started, previous Tx still in
> > process (status 0x%08x)\n",
> > > +                                    intel_dp->aux.name, status);
> > > +                           if (try > 3)
> > > +                                   goto out;
> > > +                           else
> > > +                                   continue;
> > > +                   }
> > >
> > > -           /* Must try at least 3 times according to DP spec */
> > > -           for (try = 0; try < 5; try++) {
> > >                     /* Load the send data into the aux channel data
> > registers */
> > >                     for (i = 0; i < send_bytes; i += 4)
> > >                             intel_de_write(i915, ch_data[i >> 2], @@ -
> > 320,8 +309,15 @@
> > > intel_dp_aux_xfer(struct intel_dp *intel_dp,
> > >
> > >                     /* Send the command and wait for it to complete */
> > >                     intel_de_write(i915, ch_ctl, send_ctl);
> > > +                   intel_de_rmw(i915, ch_ctl,
> > DP_AUX_CH_CTL_INTERRUPT |
> > > +                                DP_AUX_CH_CTL_TIME_OUT_ERROR |
> > > +                                DP_AUX_CH_CTL_RECEIVE_ERROR, 0);
> > >
> > > -                   status = intel_dp_aux_wait_done(intel_dp);
> >
> > The review comments were not addressed and these changes still don't
> > make sense to me. What I meant is - instead of all the above changes -
> > bailing out at this point if DP_AUX_CH_CTL_SEND_BUSY is still set in status.
> 
> I think my 2st patch version had considered this SEND_BUSY bit. In the
> beginning of this loop there is a check for SEND_BUSY to ensure that
> the previous aux transaction is complete.
>
> Then we write the data and here we check for error(timeout or receive)
> only. If SEND_BUSY is checked over here again the code for aux
> transaction in progress check will be duplicated.

There is already a check in the current code for SEND_BUSY before the
first transaction attempt. Any subsequent error handling, including
checking for SEND_BUSY being still set, should be done at one place
after waiting for the transaction to complete (along with TIME_OUT_ERROR
and RECEIVE_ERROR checks). I don't see a reason to repeat the call to
intel_dp_aux_wait_done() as in this patch, right after it has already
timed out.

> Will be floating v6 patch which takes care of this SEND_BUSY and acts
> upon properly.
> 
> Thanks and Regards,
> Arun R Murthy
> --------------------
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 2d8297f8d088..0942b109b4ca 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1741,7 +1741,6 @@  struct intel_dp {
 	/* sink or branch descriptor */
 	struct drm_dp_desc desc;
 	struct drm_dp_aux aux;
-	u32 aux_busy_last_status;
 	u8 train_set[4];
 
 	struct intel_pps pps;
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
index 0c27db8ae4f1..244b4d7d716d 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
@@ -36,25 +36,24 @@  static void intel_dp_aux_unpack(u32 src, u8 *dst, int dst_bytes)
 		dst[i] = src >> ((3 - i) * 8);
 }
 
-static u32
-intel_dp_aux_wait_done(struct intel_dp *intel_dp)
+static int
+intel_dp_aux_wait_done(struct intel_dp *intel_dp, u32 *status)
 {
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	i915_reg_t ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp);
 	const unsigned int timeout_ms = 10;
-	u32 status;
 	int ret;
 
 	ret = __intel_de_wait_for_register(i915, ch_ctl,
 					   DP_AUX_CH_CTL_SEND_BUSY, 0,
-					   2, timeout_ms, &status);
+					   50, timeout_ms, status);
 
 	if (ret == -ETIMEDOUT)
 		drm_err(&i915->drm,
 			"%s: did not complete or timeout within %ums (status 0x%08x)\n",
-			intel_dp->aux.name, timeout_ms, status);
+			intel_dp->aux.name, timeout_ms, *status);
 
-	return status;
+	return ret;
 }
 
 static u32 g4x_get_aux_clock_divider(struct intel_dp *intel_dp, int index)
@@ -186,10 +185,7 @@  static u32 skl_get_aux_send_ctl(struct intel_dp *intel_dp,
 	 */
 	ret = DP_AUX_CH_CTL_SEND_BUSY |
 		DP_AUX_CH_CTL_DONE |
-		DP_AUX_CH_CTL_INTERRUPT |
-		DP_AUX_CH_CTL_TIME_OUT_ERROR |
 		DP_AUX_CH_CTL_TIME_OUT_MAX |
-		DP_AUX_CH_CTL_RECEIVE_ERROR |
 		DP_AUX_CH_CTL_MESSAGE_SIZE(send_bytes) |
 		DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(intel_dp_aux_fw_sync_len()) |
 		DP_AUX_CH_CTL_SYNC_PULSE_SKL(intel_dp_aux_sync_len());
@@ -273,30 +269,6 @@  intel_dp_aux_xfer(struct intel_dp *intel_dp,
 	 * it using the same AUX CH simultaneously
 	 */
 
-	/* Try to wait for any previous AUX channel activity */
-	for (try = 0; try < 3; try++) {
-		status = intel_de_read_notrace(i915, ch_ctl);
-		if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0)
-			break;
-		msleep(1);
-	}
-	/* just trace the final value */
-	trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
-
-	if (try == 3) {
-		const u32 status = intel_de_read(i915, ch_ctl);
-
-		if (status != intel_dp->aux_busy_last_status) {
-			drm_WARN(&i915->drm, 1,
-				 "%s: not started (status 0x%08x)\n",
-				 intel_dp->aux.name, status);
-			intel_dp->aux_busy_last_status = status;
-		}
-
-		ret = -EBUSY;
-		goto out;
-	}
-
 	/* Only 5 data registers! */
 	if (drm_WARN_ON(&i915->drm, send_bytes > 20 || recv_size > 20)) {
 		ret = -E2BIG;
@@ -304,14 +276,31 @@  intel_dp_aux_xfer(struct intel_dp *intel_dp,
 	}
 
 	while ((aux_clock_divider = intel_dp->get_aux_clock_divider(intel_dp, clock++))) {
-		u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
+		/* Must try at least 3 times according to DP spec */
+		for (try = 0; try < 5; try++) {
+			u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
 							  send_bytes,
 							  aux_clock_divider);
 
-		send_ctl |= aux_send_ctl_flags;
+			send_ctl |= aux_send_ctl_flags;
+
+			/* Try to wait for any previous AUX channel activity */
+			/* TODO: if typeC then 4.2ms else 800us. For DG2 add 1.5ms for both cases */
+			ret = intel_dp_aux_wait_done(intel_dp, &status);
+			/* just trace the final value */
+			trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
+
+			/* On timeout dont read the status bits as its not updated */
+			if (ret == -ETIMEDOUT) {
+				drm_WARN(&i915->drm, 1,
+					 "%s: not started, previous Tx still in process (status 0x%08x)\n",
+					 intel_dp->aux.name, status);
+				if (try > 3)
+					goto out;
+				else
+					continue;
+			}
 
-		/* Must try at least 3 times according to DP spec */
-		for (try = 0; try < 5; try++) {
 			/* Load the send data into the aux channel data registers */
 			for (i = 0; i < send_bytes; i += 4)
 				intel_de_write(i915, ch_data[i >> 2],
@@ -320,8 +309,15 @@  intel_dp_aux_xfer(struct intel_dp *intel_dp,
 
 			/* Send the command and wait for it to complete */
 			intel_de_write(i915, ch_ctl, send_ctl);
+			intel_de_rmw(i915, ch_ctl, DP_AUX_CH_CTL_INTERRUPT |
+				     DP_AUX_CH_CTL_TIME_OUT_ERROR |
+				     DP_AUX_CH_CTL_RECEIVE_ERROR, 0);
 
-			status = intel_dp_aux_wait_done(intel_dp);
+			ret = intel_dp_aux_wait_done(intel_dp, &status);
+
+			/* On timeout dont read the status bits as its not updated */
+			if (ret == -ETIMEDOUT)
+				continue;
 
 			/* Clear done status and any errors */
 			intel_de_write(i915, ch_ctl,