disp: msm: sde: fix dsc reservation logic

In current SDE driver, DSC resource allocation is done in
reverse order for DP displays. If this DSC resource allocation
invoked with array previously chosen DSC blocks, dereferencing
the array should be in same order of resource allocation to
avoid index mismatch and resource allocation failure.

Change-Id: I83fb74e6677effcf6ddaeea45a0bd6140fd1e6d5
Signed-off-by: Prabhanjan Kandula <[email protected]>

msm/sde/sde_rm.c

@@ -1644,16 +1644,15 @@ static int _sde_rm_reserve_dsc(
 	/* Find a first DSC */
 	while (alloc_count != num_dsc_enc &&
 			_sde_rm_get_hw_locked(rm, &iter_i, list_forward)) {
-		const struct sde_hw_dsc *hw_dsc = to_sde_hw_dsc(
-				iter_i.blk->hw);
+		int req_index = list_forward ? alloc_count : (num_dsc_enc - alloc_count - 1);
+		const struct sde_hw_dsc *hw_dsc = to_sde_hw_dsc(iter_i.blk->hw);
 		unsigned long features = hw_dsc->caps->features;
-		bool has_422_420_support =
-			BIT(SDE_DSC_NATIVE_422_EN) & features;
+		bool has_422_420_support = BIT(SDE_DSC_NATIVE_422_EN) & features;
 
 		if (reserve_mask & (1 << iter_i.blk->id))
 			continue;
 
-		if (_dsc_ids && (iter_i.blk->id != _dsc_ids[alloc_count]))
+		if (_dsc_ids && (iter_i.blk->id != _dsc_ids[req_index]))
 			continue;
 
 		/* if this hw block does not support required feature */
@@ -1668,7 +1667,7 @@ static int _sde_rm_reserve_dsc(
 		SDE_DEBUG("blk id = %d, _dsc_ids[%d] = %d\n",
 			iter_i.blk->id,
 			alloc_count,
-			_dsc_ids ? _dsc_ids[alloc_count] : -1);
+			_dsc_ids ? _dsc_ids[req_index] : -1);
 
 		/* reset and restart from current block if allocated dsc blocks are not contiguous */
 		if (alloc_count >= 1 && (abs(dsc[alloc_count - 1]->id - iter_i.blk->id) != 1)) {
@@ -1687,11 +1686,12 @@ static int _sde_rm_reserve_dsc(
 		sde_rm_init_hw_iter(&iter_j, 0, SDE_HW_BLK_DSC);
 
 		while (_sde_rm_get_hw_locked(rm, &iter_j, list_forward)) {
+			req_index = list_forward ? alloc_count : (num_dsc_enc - alloc_count - 1);
 			if (reserve_mask & (1 << iter_j.blk->id))
 				continue;
 
 			if (_dsc_ids && (iter_j.blk->id !=
-					_dsc_ids[alloc_count]))
+					_dsc_ids[req_index]))
 				continue;
 
 			if (!_sde_rm_check_dsc(rm, rsvp, iter_j.blk,
@@ -1701,7 +1701,7 @@ static int _sde_rm_reserve_dsc(
 			SDE_DEBUG("blk id = %d, _dsc_ids[%d] = %d\n",
 				iter_j.blk->id,
 				alloc_count,
-				_dsc_ids ? _dsc_ids[alloc_count] : -1);
+				_dsc_ids ? _dsc_ids[req_index] : -1);
 
 			reserve_mask |= (1 << iter_j.blk->id);
 			dsc[alloc_count++] = iter_j.blk;