bus: mhi: host: Avoid ringing EV DB if there are no elements to process

Currently, mhi_process_data_event_ring()/mhi_process_ctrl_ev_ring() APIs are ringing DB even if there are no ring elements to process. This could cause the device to process the DB event in the absence of ring elements. So to avoid this unnecessary device processing, let's ring event DB only if there are any ring elements to process. Signed-off-by: Vivek Pernamitta <[email protected]> Reviewed-by: Jeffrey Hugo <[email protected]> Reviewed-by: Manivannan Sadhasivam <[email protected]> Link: https://lore.kernel.org/r/[email protected] [mani: massaged the commit message a bit] Signed-off-by: Manivannan Sadhasivam <[email protected]>
niw · Apr 10, 2023 · 4308c68 · 4308c68
1 parent c2dbd34
commit 4308c68
Showing 1 changed file with 6 additions and 2 deletions.
diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
@@ -961,7 +961,9 @@ int mhi_process_ctrl_ev_ring(struct mhi_controller *mhi_cntrl,
 	}
 
 	read_lock_bh(&mhi_cntrl->pm_lock);
-	if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl)))
+
+	/* Ring EV DB only if there is any pending element to process */
+	if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl)) && count)
 		mhi_ring_er_db(mhi_event);
 	read_unlock_bh(&mhi_cntrl->pm_lock);
 
@@ -1031,7 +1033,9 @@ int mhi_process_data_event_ring(struct mhi_controller *mhi_cntrl,
 		count++;
 	}
 	read_lock_bh(&mhi_cntrl->pm_lock);
-	if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl)))
+
+	/* Ring EV DB only if there is any pending element to process */
+	if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl)) && count)
 		mhi_ring_er_db(mhi_event);
 	read_unlock_bh(&mhi_cntrl->pm_lock);