drm/amdgpu: Fix allocating extra dwords for rings (v2)

Rename extra_dw to extra_bytes and document what it's for.

The value is already used as if it were bytes in vcn_v4_0.c
and in amdgpu_ring_init. Just adjust the dword count in
jpeg_v1_0.c so that it becomes a byte count.

v2:
Rename extra_dw to extra_bytes as discussed during review.

Fixes: c8c1a1d2ef04 ("drm/amdgpu: define and add extra dword for jpeg ring")
Signed-off-by: Timur Kristóf <[e-mail]>
Reviewed-by: Christian König <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c

···
 
 	/* Allocate ring buffer */
 	if (ring->ring_obj == NULL) {
-		r = amdgpu_bo_create_kernel(adev, ring->ring_size + ring->funcs->extra_dw, PAGE_SIZE,
+		r = amdgpu_bo_create_kernel(adev, ring->ring_size + ring->funcs->extra_bytes,
+					    PAGE_SIZE,
 					    AMDGPU_GEM_DOMAIN_GTT,
 					    &ring->ring_obj,
 					    &ring->gpu_addr,

drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h

···
 	bool			support_64bit_ptrs;
 	bool			no_user_fence;
 	bool			secure_submission_supported;
-	unsigned		extra_dw;
+
+	/**
+	 * @extra_bytes:
+	 *
+	 * Optional extra space in bytes that is added to the ring size
+	 * when allocating the BO that holds the contents of the ring.
+	 * This space isn't used for command submission to the ring,
+	 * but is just there to satisfy some hardware requirements or
+	 * implement workarounds. It's up to the implementation of each
+	 * specific ring to initialize this space.
+	 */
+	unsigned		extra_bytes;
 
 	/* ring read/write ptr handling */
 	u64 (*get_rptr)(struct amdgpu_ring *ring);

drivers/gpu/drm/amd/amdgpu/jpeg_v1_0.c

···
 	.nop = PACKET0(0x81ff, 0),
 	.support_64bit_ptrs = false,
 	.no_user_fence = true,
-	.extra_dw = 64,
+	.extra_bytes = 256,
 	.get_rptr = jpeg_v1_0_decode_ring_get_rptr,
 	.get_wptr = jpeg_v1_0_decode_ring_get_wptr,
 	.set_wptr = jpeg_v1_0_decode_ring_set_wptr,

drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c

···
 	.type = AMDGPU_RING_TYPE_VCN_ENC,
 	.align_mask = 0x3f,
 	.nop = VCN_ENC_CMD_NO_OP,
-	.extra_dw = sizeof(struct amdgpu_vcn_rb_metadata),
+	.extra_bytes = sizeof(struct amdgpu_vcn_rb_metadata),
 	.get_rptr = vcn_v4_0_unified_ring_get_rptr,
 	.get_wptr = vcn_v4_0_unified_ring_get_wptr,
 	.set_wptr = vcn_v4_0_unified_ring_set_wptr,