drivers/gpu/drm/amd/display/modules/vmid/vmid.c

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/amd/display/modules/vmid/vmid.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/amd/display/modules/vmid/vmid.c
Extension
.c
Size
4702 bytes
Lines
179
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct core_vmid {
	struct mod_vmid public;
	struct dc *dc;

	unsigned int num_vmid;
	unsigned int num_vmids_available;
	uint64_t ptb_assigned_to_vmid[MAX_VMID];
	struct dc_virtual_addr_space_config base_config;
};

#define MOD_VMID_TO_CORE(mod_vmid)\
		container_of(mod_vmid, struct core_vmid, public)

static void add_ptb_to_table(struct core_vmid *core_vmid, unsigned int vmid, uint64_t ptb)
{
	if (vmid < MAX_VMID) {
		core_vmid->ptb_assigned_to_vmid[vmid] = ptb;
		core_vmid->num_vmids_available--;
	}
}

static void clear_entry_from_vmid_table(struct core_vmid *core_vmid, unsigned int vmid)
{
	if (vmid < MAX_VMID) {
		core_vmid->ptb_assigned_to_vmid[vmid] = 0;
		core_vmid->num_vmids_available++;
	}
}

static void evict_vmids(struct core_vmid *core_vmid)
{
	unsigned int i;
	int ord_int = dc_get_vmid_use_vector(core_vmid->dc);

	ASSERT(ord_int >= 0 && ord_int <= 0xFFFF);
	uint16_t ord = (uint16_t)ord_int;

	// At this point any positions with value 0 are unused vmids, evict them
	for (i = 1; i < core_vmid->num_vmid; i++) {
		if (!(ord & (1u << i)))
			clear_entry_from_vmid_table(core_vmid, i);
	}
}

// Return value of -1 indicates vmid table uninitialized or ptb dne in the table
static int get_existing_vmid_for_ptb(struct core_vmid *core_vmid, uint64_t ptb)
{
	unsigned int i;

	for (i = 0; i < core_vmid->num_vmid; i++) {
		if (core_vmid->ptb_assigned_to_vmid[i] == ptb)
			return i;
	}

	return -1;
}

// Expected to be called only when there's an available vmid
static int get_next_available_vmid(struct core_vmid *core_vmid)
{
	unsigned int i;

	for (i = 1; i < core_vmid->num_vmid; i++) {
		if (core_vmid->ptb_assigned_to_vmid[i] == 0)
			return i;
	}

	return -1;
}

uint8_t mod_vmid_get_for_ptb(struct mod_vmid *mod_vmid, uint64_t ptb)
{
	struct core_vmid *core_vmid = MOD_VMID_TO_CORE(mod_vmid);
	int vmid = 0;

	// Physical address gets vmid 0
	if (ptb == 0)
		return 0;

	vmid = get_existing_vmid_for_ptb(core_vmid, ptb);

	if (vmid == -1) {
		struct dc_virtual_addr_space_config va_config = core_vmid->base_config;

		va_config.page_table_base_addr = ptb;

		if (core_vmid->num_vmids_available == 0)
			evict_vmids(core_vmid);

		vmid = get_next_available_vmid(core_vmid);

Annotation

Implementation Notes