drm/amdgpu: simplify allocation of scratch regs

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.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Nils Wallménius <nils.wallmenius@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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 ffeda245f38b..953148058bdb 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 01a42b6a69a4..19943356cca7 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 b323f5ef64d2..e0132436c76f 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 c4e14015ec5b..cfed6db69b93 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 c8c45ba952c8..69543d4eef34 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)