drm/msm/mdp5: Write to SMP registers even if allocations don't change

Requests for assigning/freeing SMP blocks by planes are collected during
the atomic check phase, and represented by mdp5_smp_state's 'assigned'
and 'released' members.

Once the atomic state is committed, these members are reset to 0,
indicating that the existing configuration satisfies all the planes.
Future atomic commits will copy the old mdp5_smp_state, and the 'assigned'
and 'released' members would be updated only if there was a change in
the plane configurations.

When we disable and re-enable display, we lose the values we wrote to the
SMP registers, but the code doesn't program the registers because there
isn't any change in mdp5_smp_state.

Fix this by writing to the registers irrespective of whether there was
a change in SMP state or not. We do this by keeping a cache of the
register values, and write them every time we commit a state.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/mdp/mdp5/mdp5_smp.c

@@ -28,6 +28,13 @@ struct mdp5_smp {
 
 	int blk_cnt;
 	int blk_size;
+
+	/* register cache */
+	u32 alloc_w[22];
+	u32 alloc_r[22];
+	u32 pipe_reqprio_fifo_wm0[SSPP_MAX];
+	u32 pipe_reqprio_fifo_wm1[SSPP_MAX];
+	u32 pipe_reqprio_fifo_wm2[SSPP_MAX];
 };
 
 static inline
@@ -98,16 +105,15 @@ static int smp_request_block(struct mdp5_smp *smp,
 static void set_fifo_thresholds(struct mdp5_smp *smp,
 		enum mdp5_pipe pipe, int nblks)
 {
-	struct mdp5_kms *mdp5_kms = get_kms(smp);
 	u32 smp_entries_per_blk = smp->blk_size / (128 / BITS_PER_BYTE);
 	u32 val;
 
 	/* 1/4 of SMP pool that is being fetched */
 	val = (nblks * smp_entries_per_blk) / 4;
 
-	mdp5_write(mdp5_kms, REG_MDP5_PIPE_REQPRIO_FIFO_WM_0(pipe), val * 1);
-	mdp5_write(mdp5_kms, REG_MDP5_PIPE_REQPRIO_FIFO_WM_1(pipe), val * 2);
-	mdp5_write(mdp5_kms, REG_MDP5_PIPE_REQPRIO_FIFO_WM_2(pipe), val * 3);
+	smp->pipe_reqprio_fifo_wm0[pipe] = val * 1;
+	smp->pipe_reqprio_fifo_wm1[pipe] = val * 2;
+	smp->pipe_reqprio_fifo_wm2[pipe] = val * 3;
 }
 
 /*
@@ -222,7 +228,6 @@ void mdp5_smp_release(struct mdp5_smp *smp, struct mdp5_smp_state *state,
 static unsigned update_smp_state(struct mdp5_smp *smp,
 		u32 cid, mdp5_smp_state_t *assigned)
 {
-	struct mdp5_kms *mdp5_kms = get_kms(smp);
 	int cnt = smp->blk_cnt;
 	unsigned nblks = 0;
 	u32 blk, val;
@@ -231,7 +236,7 @@ static unsigned update_smp_state(struct mdp5_smp *smp,
 		int idx = blk / 3;
 		int fld = blk % 3;
 
-		val = mdp5_read(mdp5_kms, REG_MDP5_SMP_ALLOC_W_REG(idx));
+		val = smp->alloc_w[idx];
 
 		switch (fld) {
 		case 0:
@@ -248,15 +253,48 @@ static unsigned update_smp_state(struct mdp5_smp *smp,
 			break;
 		}
 
-		mdp5_write(mdp5_kms, REG_MDP5_SMP_ALLOC_W_REG(idx), val);
-		mdp5_write(mdp5_kms, REG_MDP5_SMP_ALLOC_R_REG(idx), val);
+		smp->alloc_w[idx] = val;
+		smp->alloc_r[idx] = val;
 
 		nblks++;
 	}
 
 	return nblks;
 }
 
+static void write_smp_alloc_regs(struct mdp5_smp *smp)
+{
+	struct mdp5_kms *mdp5_kms = get_kms(smp);
+	int i, num_regs;
+
+	num_regs = smp->blk_cnt / 3 + 1;
+
+	for (i = 0; i < num_regs; i++) {
+		mdp5_write(mdp5_kms, REG_MDP5_SMP_ALLOC_W_REG(i),
+			   smp->alloc_w[i]);
+		mdp5_write(mdp5_kms, REG_MDP5_SMP_ALLOC_R_REG(i),
+			   smp->alloc_r[i]);
+	}
+}
+
+static void write_smp_fifo_regs(struct mdp5_smp *smp)
+{
+	struct mdp5_kms *mdp5_kms = get_kms(smp);
+	int i;
+
+	for (i = 0; i < mdp5_kms->num_hwpipes; i++) {
+		struct mdp5_hw_pipe *hwpipe = mdp5_kms->hwpipes[i];
+		enum mdp5_pipe pipe = hwpipe->pipe;
+
+		mdp5_write(mdp5_kms, REG_MDP5_PIPE_REQPRIO_FIFO_WM_0(pipe),
+			   smp->pipe_reqprio_fifo_wm0[pipe]);
+		mdp5_write(mdp5_kms, REG_MDP5_PIPE_REQPRIO_FIFO_WM_1(pipe),
+			   smp->pipe_reqprio_fifo_wm1[pipe]);
+		mdp5_write(mdp5_kms, REG_MDP5_PIPE_REQPRIO_FIFO_WM_2(pipe),
+			   smp->pipe_reqprio_fifo_wm2[pipe]);
+	}
+}
+
 void mdp5_smp_prepare_commit(struct mdp5_smp *smp, struct mdp5_smp_state *state)
 {
 	enum mdp5_pipe pipe;
@@ -277,6 +315,9 @@ void mdp5_smp_prepare_commit(struct mdp5_smp *smp, struct mdp5_smp_state *state)
 		set_fifo_thresholds(smp, pipe, nblks);
 	}
 
+	write_smp_alloc_regs(smp);
+	write_smp_fifo_regs(smp);
+
 	state->assigned = 0;
 }
 
@@ -289,6 +330,8 @@ void mdp5_smp_complete_commit(struct mdp5_smp *smp, struct mdp5_smp_state *state
 		set_fifo_thresholds(smp, pipe, 0);
 	}
 
+	write_smp_fifo_regs(smp);
+
 	state->released = 0;
 }