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Commit 2a57e9b5 authored by Laurent Pinchart's avatar Laurent Pinchart
Browse files

drm: rcar-du: Keep plane to CRTC associations when disabling a plane 



Changing the plane to CRTC associations requires restarting the CRTC
group, creating visible flicker. Mitigate the issue by changing plane
association only when a plane becomes enabled, not when it get disabled.

Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
parent 08058611

drivers/gpu/drm/rcar-du/rcar_du_crtc.c

+28 −20
Original line number Diff line number Diff line
@@ -208,9 +208,10 @@ static void rcar_du_crtc_update_planes(struct rcar_du_crtc *rcrtc) 
{

	struct rcar_du_plane *planes[RCAR_DU_NUM_HW_PLANES];

	unsigned int num_planes = 0;

	unsigned int dptsr_planes;

	unsigned int hwplanes = 0;

	unsigned int prio = 0;

	unsigned int i;

	u32 dptsr = 0;

	u32 dspr = 0;



	for (i = 0; i < ARRAY_SIZE(rcrtc->group->planes); ++i) {
@@ -238,36 +239,43 @@ static void rcar_du_crtc_update_planes(struct rcar_du_crtc *rcrtc) 


		prio -= 4;

		dspr |= (index + 1) << prio;

		dptsr |= DPTSR_PnDK(index) |  DPTSR_PnTS(index);

		hwplanes |= 1 << index;



		if (plane_format(plane)->planes == 2) {

			index = (index + 1) % 8;



			prio -= 4;

			dspr |= (index + 1) << prio;

			dptsr |= DPTSR_PnDK(index) |  DPTSR_PnTS(index);

			hwplanes |= 1 << index;

		}

	}



	/* Select display timing and dot clock generator 2 for planes associated

	 * with superposition controller 2.

	 */

	if (rcrtc->index % 2) {

		/* The DPTSR register is updated when the display controller is

		 * stopped. We thus need to restart the DU. Once again, sorry

		 * for the flicker. One way to mitigate the issue would be to

		 * pre-associate planes with CRTCs (either with a fixed 4/4

		 * split, or through a module parameter). Flicker would then

		 * occur only if we need to break the pre-association.

	/* Update the planes to display timing and dot clock generator

	 * associations.

	 *

	 * Updating the DPTSR register requires restarting the CRTC group,

	 * resulting in visible flicker. To mitigate the issue only update the

	 * association if needed by enabled planes. Planes being disabled will

	 * keep their current association.

	 *

	 * To mitigate the issue further we could pre-associate planes with

	 * CRTCs, either with a fixed 4/4 split, or through a module parameter.

	 */

	mutex_lock(&rcrtc->group->lock);

		if (rcar_du_group_read(rcrtc->group, DPTSR) != dptsr) {

			rcar_du_group_write(rcrtc->group, DPTSR, dptsr);



	dptsr_planes = rcrtc->index % 2 ? rcrtc->group->dptsr_planes | hwplanes

		     : rcrtc->group->dptsr_planes & ~hwplanes;



	if (dptsr_planes != rcrtc->group->dptsr_planes) {

		rcar_du_group_write(rcrtc->group, DPTSR,

				    (dptsr_planes << 16) | dptsr_planes);

		rcrtc->group->dptsr_planes = dptsr_planes;



		if (rcrtc->group->used_crtcs)

			rcar_du_group_restart(rcrtc->group);

	}



	mutex_unlock(&rcrtc->group->lock);

	}



	rcar_du_group_write(rcrtc->group, rcrtc->index % 2 ? DS2PR : DS1PR,

			    dspr);

drivers/gpu/drm/rcar-du/rcar_du_group.c

+6 −0
Original line number Diff line number Diff line
@@ -85,6 +85,12 @@ static void rcar_du_group_setup(struct rcar_du_group *rgrp) 
	 * superposition 0 to DU0 pins. DU1 pins will be configured dynamically.

	 */

	rcar_du_group_write(rgrp, DORCR, DORCR_PG1D_DS1 | DORCR_DPRS);



	/* Apply planes to CRTCs association. */

	mutex_lock(&rgrp->lock);

	rcar_du_group_write(rgrp, DPTSR, (rgrp->dptsr_planes << 16) |

			    rgrp->dptsr_planes);

	mutex_unlock(&rgrp->lock);

}



/*

drivers/gpu/drm/rcar-du/rcar_du_group.h

+3 −1
Original line number Diff line number Diff line
@@ -27,7 +27,8 @@ struct rcar_du_device; 
 * @index: group index

 * @use_count: number of users of the group (rcar_du_group_(get|put))

 * @used_crtcs: number of CRTCs currently in use

 * @lock: protects the DPTSR register

 * @lock: protects the dptsr_planes field and the DPTSR register

 * @dptsr_planes: bitmask of planes driven by dot-clock and timing generator 1

 * @planes: planes handled by the group

 */

struct rcar_du_group {
@@ -39,6 +40,7 @@ struct rcar_du_group { 
	unsigned int used_crtcs;



	struct mutex lock;

	unsigned int dptsr_planes;



	struct rcar_du_plane planes[RCAR_DU_NUM_KMS_PLANES];

};