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,
Tvrtko
As 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)@@ -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);Regards,
Tvrtko