[PATCH v2 3/3] drm/nouveau: begin documenting core nouveau structures

From: Lyude Paul
Date: Fri Mar 26 2021 - 20:19:01 EST


From: Jeremy Cline <jcline@xxxxxxxxxx>

Start on documentation for the Nouveau device structure and the NVIF
client structure it uses. This documentation is not complete as the
structures are non-trivial and I am not familiar with large portions of
them.

Signed-off-by: Jeremy Cline <jcline@xxxxxxxxxx>
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nouveau_drv.h | 67 +++++++++++++++++++++++++++
1 file changed, 67 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
index 8eb133fd6df0..43d751d2445f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -88,8 +88,20 @@ enum nouveau_drm_handle {
NVDRM_NVSW = 0x55550000,
};

+/**
+ * struct nouveau_cli - A DRM-specific NVIF client.
+ *
+ * This encapsulates a NVIF client and is intended to be the sole interface
+ * between the DRM APIs and NVKM. An instance of this structure is allocated
+ * for each userspace client when they open the device file. Additionally,
+ * there are several allocated strictly for the kernel's use.
+ */
struct nouveau_cli {
struct nvif_client base;
+
+ /**
+ * @drm: A reference to the device that the client is associated with.
+ */
struct nouveau_drm *drm;
struct mutex mutex;

@@ -99,6 +111,9 @@ struct nouveau_cli {
struct nouveau_vmm svm;
const struct nvif_mclass *mem;

+ /**
+ * @head: The list entry for this client in the @drm device's list of clients.
+ */
struct list_head head;
void *abi16;
struct list_head objects;
@@ -106,13 +121,36 @@ struct nouveau_cli {
char name[32];

struct work_struct work;
+
+ /**
+ * @worker: List of pending &struct nouveau_cli_work associated with this client.
+ */
struct list_head worker;
+
+ /**
+ * @lock: Protects the @worker list. Additionally, this lock on the
+ * @drm.master instance is used to serialize destruction of the @base
+ * member in this structure, as well as the destruction of the &struct
+ * nvif_mem embedded in &struct nouveau_mem instances.
+ */
struct mutex lock;
};

+/**
+ * struct nouveau_cli_work - A pending work item for an NVIF client.
+ */
struct nouveau_cli_work {
void (*func)(struct nouveau_cli_work *);
+
+ /**
+ * @cli: Reference to the NVIF client this work belongs to.
+ */
struct nouveau_cli *cli;
+
+ /**
+ * @head: The list entry for this work item in the &struct nouveau_cli
+ * worker list.
+ */
struct list_head head;

struct dma_fence *fence;
@@ -131,9 +169,32 @@ nouveau_cli(struct drm_file *fpriv)
#include <nvif/object.h>
#include <nvif/parent.h>

+/**
+ * struct nouveau_drm - The nouveau-specific device structure.
+ *
+ * This structure is allocated for a device when it is probed and keeps track
+ * of all the nouveau-specific device details. The lifetime of this structure
+ * is the same as the lifetime of a &struct drm_device and is managed by the
+ * DRM layer.
+ */
struct nouveau_drm {
+ /**
+ * @parent: Implementation of the interface required to use the NVIF_DEBUG
+ * and NVIF_ERROR macros
+ */
struct nvif_parent parent;
+
+ /**
+ * @master: This NVIF client is used to initialize the NVIF driver and used
+ * for TTM memory allocations. It is the root of the NVIF object tree.
+ */
struct nouveau_cli master;
+
+ /**
+ * @client: This NVIF client is used by the DRM layer to interact with
+ * the NVKM layer for everything except TTM memory allocations. It, and
+ * all other clients, are children of the primary (@master) client.
+ */
struct nouveau_cli client;

/**
@@ -141,6 +202,12 @@ struct nouveau_drm {
*/
struct drm_device drm_dev;

+ /**
+ * @clients: List of all &struct nouveau_cli allocated for userspace
+ * associated with this DRM device. Clients are allocated when the DRM
+ * file is opened and deallocated when the file is closed. This list is
+ * protected by the mutex in @client.
+ */
struct list_head clients;

u8 old_pm_cap;
--
2.30.2