drm/nouveau: exec: report max pushs through getparam

Report the maximum number of IBs that can be pushed with a single DRM_IOCTL_NOUVEAU_EXEC through DRM_IOCTL_NOUVEAU_GETPARAM. While the maximum number of IBs per ring might vary between chipsets, the kernel will make sure that userspace can only push a fraction of the maximum number of IBs per ring per job, such that we avoid a situation where there's only a single job occupying the ring, which could potentially lead to the ring run dry. Using DRM_IOCTL_NOUVEAU_GETPARAM to report the maximum number of IBs that can be pushed with a single DRM_IOCTL_NOUVEAU_EXEC implies that all channels of a given device have the same ring size.

Danilo Krummrich committed 3 years ago

Commit d59e75e1 parent bbe08a06 files · +49 −4Browse files

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include/uapi/drm/nouveau_drm.h+10−0

@@ -44,6 +44,16 @@ extern "C" { · 43 unmodified lines
44	44	#define NOUVEAU_GETPARAM_PTIMER_TIME 14
45	45	#define NOUVEAU_GETPARAM_HAS_BO_USAGE 15
46	46	#define NOUVEAU_GETPARAM_HAS_PAGEFLIP 16
	47	+
	48	+/**
	49	+ * @NOUVEAU_GETPARAM_EXEC_PUSH_MAX
	50	+ *
	51	+ * Query the maximum amount of IBs that can be pushed through a single
	52	+ * &drm_nouveau_exec structure and hence a single &DRM_IOCTL_NOUVEAU_EXEC
	53	+ * ioctl().
	54	+ */
	55	+#define NOUVEAU_GETPARAM_EXEC_PUSH_MAX 17
	56	+
47	57	struct drm_nouveau_getparam {
48	58	__u64 param;
49	59	__u64 value;