diff mbox series

[2/6] drm/vc4: Move LBM creation out of vc4_plane_mode_set()

Message ID 20181115103721.25601-3-boris.brezillon@bootlin.com (mailing list archive)
State New, archived
Headers show
Series drm/vc4: Allow scaling on cursor planes | expand

Commit Message

Boris Brezillon Nov. 15, 2018, 10:37 a.m. UTC
We are about to use vc4_plane_mode_set() in the async check path, and
async updates require that LBM size stay the same since they reuse the
LBM from the previous state. So we definitely don't want to allocate a
new LBM region that we know for sure will be free right away.

Move the LBM allocation out of vc4_plane_mode_set() and call the new
function (vc4_plane_update_lbm()) from vc4_plane_atomic_check().

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
 drivers/gpu/drm/vc4/vc4_drv.h   |  1 +
 drivers/gpu/drm/vc4/vc4_plane.c | 82 ++++++++++++++++++++++-----------
 2 files changed, 55 insertions(+), 28 deletions(-)

Comments

Eric Anholt Nov. 15, 2018, 8:39 p.m. UTC | #1
Boris Brezillon <boris.brezillon@bootlin.com> writes:

> We are about to use vc4_plane_mode_set() in the async check path, and
> async updates require that LBM size stay the same since they reuse the
> LBM from the previous state. So we definitely don't want to allocate a
> new LBM region that we know for sure will be free right away.
>
> Move the LBM allocation out of vc4_plane_mode_set() and call the new
> function (vc4_plane_update_lbm()) from vc4_plane_atomic_check().
>
> Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> ---
>  drivers/gpu/drm/vc4/vc4_drv.h   |  1 +
>  drivers/gpu/drm/vc4/vc4_plane.c | 82 ++++++++++++++++++++++-----------
>  2 files changed, 55 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> index bd6ef1f31822..9ed05fb61eb6 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.h
> +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> @@ -338,6 +338,7 @@ struct vc4_plane_state {
>  	u32 pos0_offset;
>  	u32 pos2_offset;
>  	u32 ptr0_offset;
> +	u32 lbm_offset;
>  
>  	/* Offset where the plane's dlist was last stored in the
>  	 * hardware at vc4_crtc_atomic_flush() time.
> diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
> index f6e3e8d33115..392a51f2bf8f 100644
> --- a/drivers/gpu/drm/vc4/vc4_plane.c
> +++ b/drivers/gpu/drm/vc4/vc4_plane.c
> @@ -452,6 +452,43 @@ static void vc4_write_scaling_parameters(struct drm_plane_state *state,
>  	}
>  }
>  
> +static int vc4_plane_update_lbm(struct drm_plane_state *state)
> +{
> +	struct vc4_dev *vc4 = to_vc4_dev(state->plane->dev);
> +	struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
> +	unsigned long irqflags;
> +	u32 lbm_size;
> +
> +	lbm_size = vc4_lbm_size(state);
> +	if (!lbm_size)
> +		return 0;
> +
> +	if (WARN_ON(!vc4_state->lbm_offset))
> +		return -EINVAL;
> +
> +	/* Allocate the LBM memory that the HVS will use for temporary
> +	 * storage due to our scaling/format conversion.
> +	 */
> +	if (!vc4_state->lbm.allocated) {
> +		int ret;
> +
> +		spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
> +		ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm,
> +						 &vc4_state->lbm,
> +						 lbm_size, 32, 0, 0);
> +		spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
> +
> +		if (ret)
> +			return ret;
> +	} else {
> +		WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
> +	}
> +
> +	vc4_state->dlist[vc4_state->lbm_offset] = vc4_state->lbm.start;
> +
> +	return 0;
> +}
> +
>  /* Writes out a full display list for an active plane to the plane's
>   * private dlist state.
>   */
> @@ -469,31 +506,12 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
>  	bool mix_plane_alpha;
>  	bool covers_screen;
>  	u32 scl0, scl1, pitch0;
> -	u32 lbm_size, tiling;
> -	unsigned long irqflags;
> +	u32 tiling;
>  	u32 hvs_format = format->hvs;
>  	int ret, i;
>  
> -	ret = vc4_plane_setup_clipping_and_scaling(state);
> -	if (ret)
> -		return ret;
> -
> -	/* Allocate the LBM memory that the HVS will use for temporary
> -	 * storage due to our scaling/format conversion.
> -	 */
> -	lbm_size = vc4_lbm_size(state);
> -	if (lbm_size) {
> -		if (!vc4_state->lbm.allocated) {
> -			spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
> -			ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm,
> -							 &vc4_state->lbm,
> -							 lbm_size, 32, 0, 0);
> -			spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
> -		} else {
> -			WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
> -		}
> -	}
>  
> +	ret = vc4_plane_setup_clipping_and_scaling(state);
>  	if (ret)
>  		return ret;
>  
> @@ -717,15 +735,18 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
>  		vc4_dlist_write(vc4_state, SCALER_CSC2_ITR_R_601_5);
>  	}
>  
> +	vc4_state->lbm_offset = 0;
> +
>  	if (vc4_state->x_scaling[0] != VC4_SCALING_NONE ||
>  	    vc4_state->x_scaling[1] != VC4_SCALING_NONE ||
>  	    vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
>  	    vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
> -		/* LBM Base Address. */
> +		/* Reserve a slot for the LBM Base Address. The real value will
> +		 * be set when calling vc4_plane_update_lbm().
> +		 */
>  		if (vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
> -		    vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
> -			vc4_dlist_write(vc4_state, vc4_state->lbm.start);
> -		}
> +		    vc4_state->y_scaling[1] != VC4_SCALING_NONE)
> +			vc4_state->lbm_offset = vc4_state->dlist_count++;
>  
>  		if (num_planes > 1) {
>  			/* Emit Cb/Cr as channel 0 and Y as channel
> @@ -785,13 +806,18 @@ static int vc4_plane_atomic_check(struct drm_plane *plane,
>  				  struct drm_plane_state *state)
>  {
>  	struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
> +	int ret;
>  
>  	vc4_state->dlist_count = 0;
>  
> -	if (plane_enabled(state))
> -		return vc4_plane_mode_set(plane, state);
> -	else
> +	if (!plane_enabled(state))
>  		return 0;
> +
> +	ret = vc4_plane_mode_set(plane, state);
> +	if (ret)
> +		return ret;
> +
> +	return vc4_plane_update_lbm(state);
>  }

Couldn't you call update_lbm() (maybe called allocate_lbm()) first, and
then leave the dlist setup as is without needing lbm_offset?
Boris Brezillon Nov. 15, 2018, 9:10 p.m. UTC | #2
On Thu, 15 Nov 2018 12:39:42 -0800
Eric Anholt <eric@anholt.net> wrote:

> Boris Brezillon <boris.brezillon@bootlin.com> writes:
> 
> > We are about to use vc4_plane_mode_set() in the async check path, and
> > async updates require that LBM size stay the same since they reuse the
> > LBM from the previous state. So we definitely don't want to allocate a
> > new LBM region that we know for sure will be free right away.
> >
> > Move the LBM allocation out of vc4_plane_mode_set() and call the new
> > function (vc4_plane_update_lbm()) from vc4_plane_atomic_check().
> >
> > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> > ---
> >  drivers/gpu/drm/vc4/vc4_drv.h   |  1 +
> >  drivers/gpu/drm/vc4/vc4_plane.c | 82 ++++++++++++++++++++++-----------
> >  2 files changed, 55 insertions(+), 28 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> > index bd6ef1f31822..9ed05fb61eb6 100644
> > --- a/drivers/gpu/drm/vc4/vc4_drv.h
> > +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> > @@ -338,6 +338,7 @@ struct vc4_plane_state {
> >  	u32 pos0_offset;
> >  	u32 pos2_offset;
> >  	u32 ptr0_offset;
> > +	u32 lbm_offset;
> >  
> >  	/* Offset where the plane's dlist was last stored in the
> >  	 * hardware at vc4_crtc_atomic_flush() time.
> > diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
> > index f6e3e8d33115..392a51f2bf8f 100644
> > --- a/drivers/gpu/drm/vc4/vc4_plane.c
> > +++ b/drivers/gpu/drm/vc4/vc4_plane.c
> > @@ -452,6 +452,43 @@ static void vc4_write_scaling_parameters(struct drm_plane_state *state,
> >  	}
> >  }
> >  
> > +static int vc4_plane_update_lbm(struct drm_plane_state *state)
> > +{
> > +	struct vc4_dev *vc4 = to_vc4_dev(state->plane->dev);
> > +	struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
> > +	unsigned long irqflags;
> > +	u32 lbm_size;
> > +
> > +	lbm_size = vc4_lbm_size(state);
> > +	if (!lbm_size)
> > +		return 0;
> > +
> > +	if (WARN_ON(!vc4_state->lbm_offset))
> > +		return -EINVAL;
> > +
> > +	/* Allocate the LBM memory that the HVS will use for temporary
> > +	 * storage due to our scaling/format conversion.
> > +	 */
> > +	if (!vc4_state->lbm.allocated) {
> > +		int ret;
> > +
> > +		spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
> > +		ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm,
> > +						 &vc4_state->lbm,
> > +						 lbm_size, 32, 0, 0);
> > +		spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
> > +
> > +		if (ret)
> > +			return ret;
> > +	} else {
> > +		WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
> > +	}
> > +
> > +	vc4_state->dlist[vc4_state->lbm_offset] = vc4_state->lbm.start;
> > +
> > +	return 0;
> > +}
> > +
> >  /* Writes out a full display list for an active plane to the plane's
> >   * private dlist state.
> >   */
> > @@ -469,31 +506,12 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
> >  	bool mix_plane_alpha;
> >  	bool covers_screen;
> >  	u32 scl0, scl1, pitch0;
> > -	u32 lbm_size, tiling;
> > -	unsigned long irqflags;
> > +	u32 tiling;
> >  	u32 hvs_format = format->hvs;
> >  	int ret, i;
> >  
> > -	ret = vc4_plane_setup_clipping_and_scaling(state);
> > -	if (ret)
> > -		return ret;
> > -
> > -	/* Allocate the LBM memory that the HVS will use for temporary
> > -	 * storage due to our scaling/format conversion.
> > -	 */
> > -	lbm_size = vc4_lbm_size(state);
> > -	if (lbm_size) {
> > -		if (!vc4_state->lbm.allocated) {
> > -			spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
> > -			ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm,
> > -							 &vc4_state->lbm,
> > -							 lbm_size, 32, 0, 0);
> > -			spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
> > -		} else {
> > -			WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
> > -		}
> > -	}
> >  
> > +	ret = vc4_plane_setup_clipping_and_scaling(state);
> >  	if (ret)
> >  		return ret;
> >  
> > @@ -717,15 +735,18 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
> >  		vc4_dlist_write(vc4_state, SCALER_CSC2_ITR_R_601_5);
> >  	}
> >  
> > +	vc4_state->lbm_offset = 0;
> > +
> >  	if (vc4_state->x_scaling[0] != VC4_SCALING_NONE ||
> >  	    vc4_state->x_scaling[1] != VC4_SCALING_NONE ||
> >  	    vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
> >  	    vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
> > -		/* LBM Base Address. */
> > +		/* Reserve a slot for the LBM Base Address. The real value will
> > +		 * be set when calling vc4_plane_update_lbm().
> > +		 */
> >  		if (vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
> > -		    vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
> > -			vc4_dlist_write(vc4_state, vc4_state->lbm.start);
> > -		}
> > +		    vc4_state->y_scaling[1] != VC4_SCALING_NONE)
> > +			vc4_state->lbm_offset = vc4_state->dlist_count++;
> >  
> >  		if (num_planes > 1) {
> >  			/* Emit Cb/Cr as channel 0 and Y as channel
> > @@ -785,13 +806,18 @@ static int vc4_plane_atomic_check(struct drm_plane *plane,
> >  				  struct drm_plane_state *state)
> >  {
> >  	struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
> > +	int ret;
> >  
> >  	vc4_state->dlist_count = 0;
> >  
> > -	if (plane_enabled(state))
> > -		return vc4_plane_mode_set(plane, state);
> > -	else
> > +	if (!plane_enabled(state))
> >  		return 0;
> > +
> > +	ret = vc4_plane_mode_set(plane, state);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return vc4_plane_update_lbm(state);
> >  }  
> 
> Couldn't you call update_lbm() (maybe called allocate_lbm()) first, and
> then leave the dlist setup as is without needing lbm_offset?

I'll anyway need lbm_offset for the dlist check I do in async_check().
Eric Anholt Nov. 20, 2018, 4:41 a.m. UTC | #3
Boris Brezillon <boris.brezillon@bootlin.com> writes:

> On Thu, 15 Nov 2018 12:39:42 -0800
> Eric Anholt <eric@anholt.net> wrote:
>
>> Boris Brezillon <boris.brezillon@bootlin.com> writes:
>> 
>> > We are about to use vc4_plane_mode_set() in the async check path, and
>> > async updates require that LBM size stay the same since they reuse the
>> > LBM from the previous state. So we definitely don't want to allocate a
>> > new LBM region that we know for sure will be free right away.
>> >
>> > Move the LBM allocation out of vc4_plane_mode_set() and call the new
>> > function (vc4_plane_update_lbm()) from vc4_plane_atomic_check().
>> >
>> > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
>> > ---
>> >  drivers/gpu/drm/vc4/vc4_drv.h   |  1 +
>> >  drivers/gpu/drm/vc4/vc4_plane.c | 82 ++++++++++++++++++++++-----------
>> >  2 files changed, 55 insertions(+), 28 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
>> > index bd6ef1f31822..9ed05fb61eb6 100644
>> > --- a/drivers/gpu/drm/vc4/vc4_drv.h
>> > +++ b/drivers/gpu/drm/vc4/vc4_drv.h
>> > @@ -338,6 +338,7 @@ struct vc4_plane_state {
>> >  	u32 pos0_offset;
>> >  	u32 pos2_offset;
>> >  	u32 ptr0_offset;
>> > +	u32 lbm_offset;
>> >  
>> >  	/* Offset where the plane's dlist was last stored in the
>> >  	 * hardware at vc4_crtc_atomic_flush() time.
>> > diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
>> > index f6e3e8d33115..392a51f2bf8f 100644
>> > --- a/drivers/gpu/drm/vc4/vc4_plane.c
>> > +++ b/drivers/gpu/drm/vc4/vc4_plane.c
>> > @@ -452,6 +452,43 @@ static void vc4_write_scaling_parameters(struct drm_plane_state *state,
>> >  	}
>> >  }
>> >  
>> > +static int vc4_plane_update_lbm(struct drm_plane_state *state)
>> > +{
>> > +	struct vc4_dev *vc4 = to_vc4_dev(state->plane->dev);
>> > +	struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
>> > +	unsigned long irqflags;
>> > +	u32 lbm_size;
>> > +
>> > +	lbm_size = vc4_lbm_size(state);
>> > +	if (!lbm_size)
>> > +		return 0;
>> > +
>> > +	if (WARN_ON(!vc4_state->lbm_offset))
>> > +		return -EINVAL;
>> > +
>> > +	/* Allocate the LBM memory that the HVS will use for temporary
>> > +	 * storage due to our scaling/format conversion.
>> > +	 */
>> > +	if (!vc4_state->lbm.allocated) {
>> > +		int ret;
>> > +
>> > +		spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
>> > +		ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm,
>> > +						 &vc4_state->lbm,
>> > +						 lbm_size, 32, 0, 0);
>> > +		spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
>> > +
>> > +		if (ret)
>> > +			return ret;
>> > +	} else {
>> > +		WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
>> > +	}
>> > +
>> > +	vc4_state->dlist[vc4_state->lbm_offset] = vc4_state->lbm.start;
>> > +
>> > +	return 0;
>> > +}
>> > +
>> >  /* Writes out a full display list for an active plane to the plane's
>> >   * private dlist state.
>> >   */
>> > @@ -469,31 +506,12 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
>> >  	bool mix_plane_alpha;
>> >  	bool covers_screen;
>> >  	u32 scl0, scl1, pitch0;
>> > -	u32 lbm_size, tiling;
>> > -	unsigned long irqflags;
>> > +	u32 tiling;
>> >  	u32 hvs_format = format->hvs;
>> >  	int ret, i;
>> >  
>> > -	ret = vc4_plane_setup_clipping_and_scaling(state);
>> > -	if (ret)
>> > -		return ret;
>> > -
>> > -	/* Allocate the LBM memory that the HVS will use for temporary
>> > -	 * storage due to our scaling/format conversion.
>> > -	 */
>> > -	lbm_size = vc4_lbm_size(state);
>> > -	if (lbm_size) {
>> > -		if (!vc4_state->lbm.allocated) {
>> > -			spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
>> > -			ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm,
>> > -							 &vc4_state->lbm,
>> > -							 lbm_size, 32, 0, 0);
>> > -			spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
>> > -		} else {
>> > -			WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
>> > -		}
>> > -	}
>> >  
>> > +	ret = vc4_plane_setup_clipping_and_scaling(state);
>> >  	if (ret)
>> >  		return ret;
>> >  
>> > @@ -717,15 +735,18 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
>> >  		vc4_dlist_write(vc4_state, SCALER_CSC2_ITR_R_601_5);
>> >  	}
>> >  
>> > +	vc4_state->lbm_offset = 0;
>> > +
>> >  	if (vc4_state->x_scaling[0] != VC4_SCALING_NONE ||
>> >  	    vc4_state->x_scaling[1] != VC4_SCALING_NONE ||
>> >  	    vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
>> >  	    vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
>> > -		/* LBM Base Address. */
>> > +		/* Reserve a slot for the LBM Base Address. The real value will
>> > +		 * be set when calling vc4_plane_update_lbm().
>> > +		 */
>> >  		if (vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
>> > -		    vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
>> > -			vc4_dlist_write(vc4_state, vc4_state->lbm.start);
>> > -		}
>> > +		    vc4_state->y_scaling[1] != VC4_SCALING_NONE)
>> > +			vc4_state->lbm_offset = vc4_state->dlist_count++;
>> >  
>> >  		if (num_planes > 1) {
>> >  			/* Emit Cb/Cr as channel 0 and Y as channel
>> > @@ -785,13 +806,18 @@ static int vc4_plane_atomic_check(struct drm_plane *plane,
>> >  				  struct drm_plane_state *state)
>> >  {
>> >  	struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
>> > +	int ret;
>> >  
>> >  	vc4_state->dlist_count = 0;
>> >  
>> > -	if (plane_enabled(state))
>> > -		return vc4_plane_mode_set(plane, state);
>> > -	else
>> > +	if (!plane_enabled(state))
>> >  		return 0;
>> > +
>> > +	ret = vc4_plane_mode_set(plane, state);
>> > +	if (ret)
>> > +		return ret;
>> > +
>> > +	return vc4_plane_update_lbm(state);
>> >  }  
>> 
>> Couldn't you call update_lbm() (maybe called allocate_lbm()) first, and
>> then leave the dlist setup as is without needing lbm_offset?
>
> I'll anyway need lbm_offset for the dlist check I do in async_check().

Fair enough.

Reviewed-by: Eric Anholt <eric@anholt.net>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index bd6ef1f31822..9ed05fb61eb6 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -338,6 +338,7 @@  struct vc4_plane_state {
 	u32 pos0_offset;
 	u32 pos2_offset;
 	u32 ptr0_offset;
+	u32 lbm_offset;
 
 	/* Offset where the plane's dlist was last stored in the
 	 * hardware at vc4_crtc_atomic_flush() time.
diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
index f6e3e8d33115..392a51f2bf8f 100644
--- a/drivers/gpu/drm/vc4/vc4_plane.c
+++ b/drivers/gpu/drm/vc4/vc4_plane.c
@@ -452,6 +452,43 @@  static void vc4_write_scaling_parameters(struct drm_plane_state *state,
 	}
 }
 
+static int vc4_plane_update_lbm(struct drm_plane_state *state)
+{
+	struct vc4_dev *vc4 = to_vc4_dev(state->plane->dev);
+	struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
+	unsigned long irqflags;
+	u32 lbm_size;
+
+	lbm_size = vc4_lbm_size(state);
+	if (!lbm_size)
+		return 0;
+
+	if (WARN_ON(!vc4_state->lbm_offset))
+		return -EINVAL;
+
+	/* Allocate the LBM memory that the HVS will use for temporary
+	 * storage due to our scaling/format conversion.
+	 */
+	if (!vc4_state->lbm.allocated) {
+		int ret;
+
+		spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
+		ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm,
+						 &vc4_state->lbm,
+						 lbm_size, 32, 0, 0);
+		spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
+
+		if (ret)
+			return ret;
+	} else {
+		WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
+	}
+
+	vc4_state->dlist[vc4_state->lbm_offset] = vc4_state->lbm.start;
+
+	return 0;
+}
+
 /* Writes out a full display list for an active plane to the plane's
  * private dlist state.
  */
@@ -469,31 +506,12 @@  static int vc4_plane_mode_set(struct drm_plane *plane,
 	bool mix_plane_alpha;
 	bool covers_screen;
 	u32 scl0, scl1, pitch0;
-	u32 lbm_size, tiling;
-	unsigned long irqflags;
+	u32 tiling;
 	u32 hvs_format = format->hvs;
 	int ret, i;
 
-	ret = vc4_plane_setup_clipping_and_scaling(state);
-	if (ret)
-		return ret;
-
-	/* Allocate the LBM memory that the HVS will use for temporary
-	 * storage due to our scaling/format conversion.
-	 */
-	lbm_size = vc4_lbm_size(state);
-	if (lbm_size) {
-		if (!vc4_state->lbm.allocated) {
-			spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
-			ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm,
-							 &vc4_state->lbm,
-							 lbm_size, 32, 0, 0);
-			spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
-		} else {
-			WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
-		}
-	}
 
+	ret = vc4_plane_setup_clipping_and_scaling(state);
 	if (ret)
 		return ret;
 
@@ -717,15 +735,18 @@  static int vc4_plane_mode_set(struct drm_plane *plane,
 		vc4_dlist_write(vc4_state, SCALER_CSC2_ITR_R_601_5);
 	}
 
+	vc4_state->lbm_offset = 0;
+
 	if (vc4_state->x_scaling[0] != VC4_SCALING_NONE ||
 	    vc4_state->x_scaling[1] != VC4_SCALING_NONE ||
 	    vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
 	    vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
-		/* LBM Base Address. */
+		/* Reserve a slot for the LBM Base Address. The real value will
+		 * be set when calling vc4_plane_update_lbm().
+		 */
 		if (vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
-		    vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
-			vc4_dlist_write(vc4_state, vc4_state->lbm.start);
-		}
+		    vc4_state->y_scaling[1] != VC4_SCALING_NONE)
+			vc4_state->lbm_offset = vc4_state->dlist_count++;
 
 		if (num_planes > 1) {
 			/* Emit Cb/Cr as channel 0 and Y as channel
@@ -785,13 +806,18 @@  static int vc4_plane_atomic_check(struct drm_plane *plane,
 				  struct drm_plane_state *state)
 {
 	struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
+	int ret;
 
 	vc4_state->dlist_count = 0;
 
-	if (plane_enabled(state))
-		return vc4_plane_mode_set(plane, state);
-	else
+	if (!plane_enabled(state))
 		return 0;
+
+	ret = vc4_plane_mode_set(plane, state);
+	if (ret)
+		return ret;
+
+	return vc4_plane_update_lbm(state);
 }
 
 static void vc4_plane_atomic_update(struct drm_plane *plane,