@@ -103,6 +103,33 @@ enum { CTB_SEND = 0, CTB_RECV = 1 };
enum { CTB_OWNER_HOST = 0 };
+/*
+ * Some H2G commands involve a synchronous response that the driver needs
+ * to wait for. In such cases, a timeout is required to prevent the driver
+ * from waiting forever in the case of an error (either no error response
+ * is defined in the protocol or something has died and requires a reset).
+ * The specific command may be defined as having a time bound response but
+ * the CT is a queue and that time guarantee only starts from the point
+ * when the command reaches the head of the queue and is processed by GuC.
+ *
+ * Ideally there would be a helper to report the progress of a given
+ * command through the CT. However, that would require a significant
+ * amount of work in the CT layer. In the meantime, provide a reasonable
+ * estimation of the worst case latency it should take for the entire
+ * queue to drain. And therefore, how long a caller should wait before
+ * giving up on their request. The current estimate is based on empirical
+ * measurement of a test that fills the buffer with context creation and
+ * destruction requests as they seem to be the slowest operation.
+ */
+long intel_guc_ct_max_queue_time_jiffies(void)
+{
+ /*
+ * A 4KB buffer full of context destroy commands takes a little
+ * over a second to process so bump that to 2s to be super safe.
+ */
+ return (CTB_H2G_BUFFER_SIZE * HZ) / SZ_2K;
+}
+
static void ct_receive_tasklet_func(struct tasklet_struct *t);
static void ct_incoming_request_worker_func(struct work_struct *w);
@@ -104,6 +104,8 @@ struct intel_guc_ct {
#endif
};
+long intel_guc_ct_max_queue_time_jiffies(void);
+
void intel_guc_ct_init_early(struct intel_guc_ct *ct);
int intel_guc_ct_init(struct intel_guc_ct *ct);
void intel_guc_ct_fini(struct intel_guc_ct *ct);