Pcode¶
Xe PCODE is the component responsible for interfacing with the PCODE firmware. It shall provide a very simple ABI to other Xe components, but be the single and consolidated place that will communicate with PCODE. All read and write operations to PCODE will be internal and private to this component.
What’s next: - PCODE hw metrics - PCODE for display operations
Internal API¶
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int xe_pcode_request(struct xe_gt *gt, u32 mbox, u32 request, u32 reply_mask, u32 reply, int timeout_base_ms)¶
send PCODE request until acknowledgment
Parameters
struct xe_gt *gt
gt
u32 mbox
PCODE mailbox ID the request is targeted for
u32 request
request ID
u32 reply_mask
mask used to check for request acknowledgment
u32 reply
value used to check for request acknowledgment
int timeout_base_ms
timeout for polling with preemption enabled
Description
Keep resending the request to mbox until PCODE acknowledges it, PCODE reports an error or an overall timeout of timeout_base_ms**+50 ms expires. The request is acknowledged once the PCODE reply dword equals **reply after applying reply_mask. Polling is first attempted with preemption enabled for timeout_base_ms and if this times out for another 50 ms with preemption disabled.
Returns 0 on success, -ETIMEDOUT
in case of a timeout, <0 in case of some
other error as reported by PCODE.
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int xe_pcode_init_min_freq_table(struct xe_gt *gt, u32 min_gt_freq, u32 max_gt_freq)¶
Initialize PCODE’s QOS frequency table
Parameters
struct xe_gt *gt
gt instance
u32 min_gt_freq
Minimal (RPn) GT frequency in units of 50MHz.
u32 max_gt_freq
Maximal (RP0) GT frequency in units of 50MHz.
Description
This function initialize PCODE’s QOS frequency table for a proper minimal frequency/power steering decision, depending on the current requested GT frequency. For older platforms this was a more complete table including the IA freq. However for the latest platforms this table become a simple 1-1 Ring vs GT frequency. Even though, without setting it, PCODE might not take the right decisions for some memory frequencies and affect latency.
It returns 0 on success, and -ERROR number on failure, -EINVAL if max frequency is higher then the minimal, and other errors directly translated from the PCODE Error returs: - -ENXIO: “Illegal Command” - -ETIMEDOUT: “Timed out” - -EINVAL: “Illegal Data” - -ENXIO, “Illegal Subcommand” - -EBUSY: “PCODE Locked” - -EOVERFLOW, “GT ratio out of range” - -EACCES, “PCODE Rejected” - -EPROTO, “Unknown”
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int xe_pcode_ready(struct xe_device *xe, bool locked)¶
Ensure PCODE is initialized
Parameters
struct xe_device *xe
xe instance
bool locked
true if lock held, false otherwise
Description
PCODE init mailbox is polled only on root gt of root tile as the root tile provides the initialization is complete only after all the tiles have completed the initialization. Called only on early probe without locks and with locks in resume path.
Returns 0 on success, and -error number on failure.
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void xe_pcode_init(struct xe_gt *gt)¶
initialize components of PCODE
Parameters
struct xe_gt *gt
gt instance
Description
This function initializes the xe_pcode component. To be called once only during probe.
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int xe_pcode_probe_early(struct xe_device *xe)¶
initializes PCODE
Parameters
struct xe_device *xe
xe instance
Description
This function checks the initialization status of PCODE To be called once only during early probe without locks.
Returns 0 on success, error code otherwise