On 26/05/2021 19:10, Matthew Brost wrote: [snip]
+static int ct_send_nb(struct intel_guc_ct *ct, + const u32 *action, + u32 len, + u32 flags) +{ + struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; + unsigned long spin_flags; + u32 fence; + int ret; + + spin_lock_irqsave(&ctb->lock, spin_flags); + + ret = ctb_has_room(ctb, len + 1); + if (unlikely(ret)) + goto out; + + fence = ct_get_next_fence(ct); + ret = ct_write(ct, action, len, fence, flags); + if (unlikely(ret)) + goto out; + + intel_guc_notify(ct_to_guc(ct)); + +out: + spin_unlock_irqrestore(&ctb->lock, spin_flags); + + return ret; +} + static int ct_send(struct intel_guc_ct *ct, const u32 *action, u32 len, @@ -473,6 +541,7 @@ static int ct_send(struct intel_guc_ct *ct, u32 response_buf_size, u32 *status) { + struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; struct ct_request request; unsigned long flags; u32 fence; @@ -482,8 +551,20 @@ static int ct_send(struct intel_guc_ct *ct, GEM_BUG_ON(!len); GEM_BUG_ON(len & ~GUC_CT_MSG_LEN_MASK); GEM_BUG_ON(!response_buf && response_buf_size); + might_sleep();Sleep is just cond_resched below or there is more?Yes, the cond_resched.+ /* + * We use a lazy spin wait loop here as we believe that if the CT + * buffers are sized correctly the flow control condition should be + * rare. + */ +retry: spin_lock_irqsave(&ct->ctbs.send.lock, flags); + if (unlikely(!ctb_has_room(ctb, len + 1))) { + spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); + cond_resched(); + goto retry; + }If this patch is about adding a non-blocking send function, and below we can see that it creates a fork: intel_guc_ct_send: ... if (flags & INTEL_GUC_SEND_NB) return ct_send_nb(ct, action, len, flags); ret = ct_send(ct, action, len, response_buf, response_buf_size, &status); Then why is there a change in ct_send here, which is not the new non-blocking path?There is not a change to ct_send(), just to intel_guc_ct_send.I was doing by the diff which says: static int ct_send(struct intel_guc_ct *ct, const u32 *action, u32 len, @@ -473,6 +541,7 @@ static int ct_send(struct intel_guc_ct *ct, u32 response_buf_size, u32 *status) { + struct intel_guc_ct_buffer *ctb = &ct->ctbs.send; struct ct_request request; unsigned long flags; u32 fence; @@ -482,8 +551,20 @@ static int ct_send(struct intel_guc_ct *ct, GEM_BUG_ON(!len); GEM_BUG_ON(len & ~GUC_CT_MSG_LEN_MASK); GEM_BUG_ON(!response_buf && response_buf_size); + might_sleep(); + /* + * We use a lazy spin wait loop here as we believe that if the CT + * buffers are sized correctly the flow control condition should be + * rare. + */ +retry: spin_lock_irqsave(&ct->ctbs.send.lock, flags); + if (unlikely(!ctb_has_room(ctb, len + 1))) { + spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); + cond_resched(); + goto retry; + } So it looks like a change to ct_send to me. Is that wrong?
What about this part - is the patch changing the blocking ct_send or not, and if it is why?
Regards, Tvrtko
Regards, TvrtkoAs for why intel_guc_ct_send is updated and we don't just a new public function, this was another reviewers suggestion. Again can't make everyone happy.fence = ct_get_next_fence(ct); request.fence = fence; @@ -495,7 +576,7 @@ static int ct_send(struct intel_guc_ct *ct, list_add_tail(&request.link, &ct->requests.pending); spin_unlock(&ct->requests.lock); - err = ct_write(ct, action, len, fence); + err = ct_write(ct, action, len, fence, 0); spin_unlock_irqrestore(&ct->ctbs.send.lock, flags); @@ -537,7 +618,7 @@ static int ct_send(struct intel_guc_ct *ct, * Command Transport (CT) buffer based GuC send function. */ int intel_guc_ct_send(struct intel_guc_ct *ct, const u32 *action, u32 len, - u32 *response_buf, u32 response_buf_size) + u32 *response_buf, u32 response_buf_size, u32 flags) { u32 status = ~0; /* undefined */ int ret; @@ -547,6 +628,9 @@ int intel_guc_ct_send(struct intel_guc_ct *ct, const u32 *action, u32 len, return -ENODEV; } + if (flags & INTEL_GUC_SEND_NB) + return ct_send_nb(ct, action, len, flags); + ret = ct_send(ct, action, len, response_buf, response_buf_size, &status); if (unlikely(ret < 0)) { CT_ERROR(ct, "Sending action %#x failed (err=%d status=%#X)\n", diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h index 1ae2dde6db93..55ef7c52472f 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h @@ -9,6 +9,7 @@ #include <linux/interrupt.h> #include <linux/spinlock.h> #include <linux/workqueue.h> +#include <linux/ktime.h> #include "intel_guc_fwif.h" @@ -42,7 +43,6 @@ struct intel_guc_ct_buffer { bool broken; }; - /** Top-level structure for Command Transport related data * * Includes a pair of CT buffers for bi-directional communication and tracking @@ -69,6 +69,9 @@ struct intel_guc_ct { struct list_head incoming; /* incoming requests */ struct work_struct worker; /* handler for incoming requests */ } requests; + + /** @stall_time: time of first time a CTB submission is stalled */ + ktime_t stall_time;Unused in this patch.Yea, wrong patch. Will fix. Matt}; void intel_guc_ct_init_early(struct intel_guc_ct *ct); @@ -88,7 +91,7 @@ static inline bool intel_guc_ct_enabled(struct intel_guc_ct *ct) } int intel_guc_ct_send(struct intel_guc_ct *ct, const u32 *action, u32 len, - u32 *response_buf, u32 response_buf_size); + u32 *response_buf, u32 response_buf_size, u32 flags); void intel_guc_ct_event_handler(struct intel_guc_ct *ct); #endif /* _INTEL_GUC_CT_H_ */Regards, Tvrtko
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