[PATCH] drm/amdgpu: simplify allocation of scratch regs

[Nils Wallménius]

The scratch regs are sequential so there's no need to keep
them in an array, we can just return the index of the first
free register + the base register. Also change the array
of bools for keeping track of the free regs to a bitfield.

Signed-off-by: Nils Wallménius <nils.wallmenius at gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h     |  3 +--
 drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c | 21 +++++++--------------
 drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c   |  7 +------
 drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c   |  7 +------
 drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c   |  7 +------
 5 files changed, 11 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index ffeda245..9531480 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -794,8 +794,7 @@ struct amdgpu_kiq {
 struct amdgpu_scratch {
 	unsigned		num_reg;
 	uint32_t                reg_base;
-	bool			free[32];
-	uint32_t		reg[32];
+	uint32_t		free_mask;
 };
 
 /*
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
index 01a42b6..1994335 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
@@ -42,12 +42,12 @@ int amdgpu_gfx_scratch_get(struct amdgpu_device *adev, uint32_t *reg)
 {
 	int i;
 
-	for (i = 0; i < adev->gfx.scratch.num_reg; i++) {
-		if (adev->gfx.scratch.free[i]) {
-			adev->gfx.scratch.free[i] = false;
-			*reg = adev->gfx.scratch.reg[i];
-			return 0;
-		}
+	i = ffs(adev->gfx.scratch.free_mask);
+	if (i != 0 && i <= adev->gfx.scratch.num_reg) {
+		i--;
+		adev->gfx.scratch.free_mask &= ~(1u << i);
+		*reg = adev->gfx.scratch.reg_base + i;
+		return 0;
 	}
 	return -EINVAL;
 }
@@ -62,14 +62,7 @@ int amdgpu_gfx_scratch_get(struct amdgpu_device *adev, uint32_t *reg)
  */
 void amdgpu_gfx_scratch_free(struct amdgpu_device *adev, uint32_t reg)
 {
-	int i;
-
-	for (i = 0; i < adev->gfx.scratch.num_reg; i++) {
-		if (adev->gfx.scratch.reg[i] == reg) {
-			adev->gfx.scratch.free[i] = true;
-			return;
-		}
-	}
+	adev->gfx.scratch.free_mask |= 1u << (reg - adev->gfx.scratch.reg_base);
 }
 
 /**
diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c
index b323f5e..e013243 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c
@@ -1794,14 +1794,9 @@ static void gfx_v6_0_gpu_init(struct amdgpu_device *adev)
 
 static void gfx_v6_0_scratch_init(struct amdgpu_device *adev)
 {
-	int i;
-
 	adev->gfx.scratch.num_reg = 7;
 	adev->gfx.scratch.reg_base = mmSCRATCH_REG0;
-	for (i = 0; i < adev->gfx.scratch.num_reg; i++) {
-		adev->gfx.scratch.free[i] = true;
-		adev->gfx.scratch.reg[i] = adev->gfx.scratch.reg_base + i;
-	}
+	adev->gfx.scratch.free_mask = (1u << adev->gfx.scratch.num_reg) - 1;
 }
 
 static int gfx_v6_0_ring_test_ring(struct amdgpu_ring *ring)
diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c
index c4e1401..cfed6db 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c
@@ -2003,14 +2003,9 @@ static void gfx_v7_0_gpu_init(struct amdgpu_device *adev)
  */
 static void gfx_v7_0_scratch_init(struct amdgpu_device *adev)
 {
-	int i;
-
 	adev->gfx.scratch.num_reg = 7;
 	adev->gfx.scratch.reg_base = mmSCRATCH_REG0;
-	for (i = 0; i < adev->gfx.scratch.num_reg; i++) {
-		adev->gfx.scratch.free[i] = true;
-		adev->gfx.scratch.reg[i] = adev->gfx.scratch.reg_base + i;
-	}
+	adev->gfx.scratch.free_mask = (1u << adev->gfx.scratch.num_reg) - 1;
 }
 
 /**
diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
index c8c45ba..69543d4 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
@@ -749,14 +749,9 @@ static void gfx_v8_0_init_golden_registers(struct amdgpu_device *adev)
 
 static void gfx_v8_0_scratch_init(struct amdgpu_device *adev)
 {
-	int i;
-
 	adev->gfx.scratch.num_reg = 7;
 	adev->gfx.scratch.reg_base = mmSCRATCH_REG0;
-	for (i = 0; i < adev->gfx.scratch.num_reg; i++) {
-		adev->gfx.scratch.free[i] = true;
-		adev->gfx.scratch.reg[i] = adev->gfx.scratch.reg_base + i;
-	}
+	adev->gfx.scratch.free_mask = (1u << adev->gfx.scratch.num_reg) - 1;
 }
 
 static int gfx_v8_0_ring_test_ring(struct amdgpu_ring *ring)
-- 
2.10.2