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* [PATCH V2] bus: mhi: host: Avoid ringing EV DB if there is no elements to process
@ 2023-02-22 10:56 Vivek Pernamitta
  0 siblings, 0 replies; only message in thread
From: Vivek Pernamitta @ 2023-02-22 10:56 UTC (permalink / raw)
  To: mhi
  Cc: quic_qianyu, manivannan.sadhasivam, quic_vbadigan, quic_krichai,
	quic_skananth, Vivek Pernamitta, Manivannan Sadhasivam,
	Alex Elder, Greg Kroah-Hartman, Hemant Kumar, Jeffrey Hugo,
	Paul Davey, Bhaumik Bhatt, open list:MHI BUS, open list

Avoid ringing Event DB if there is no elements to process.
As mhi_poll function can be called by mhi client drivers
which will call process_event, which will ring DB even if
there no ring elements to process.

Signed-off-by: Vivek Pernamitta <quic_vpernami@quicinc.com>
---
 drivers/bus/mhi/host/main.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index df0fbfe..0311a31 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -961,7 +961,7 @@ 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)))
+	if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl)) && count)
 		mhi_ring_er_db(mhi_event);
 	read_unlock_bh(&mhi_cntrl->pm_lock);
 
@@ -1031,7 +1031,9 @@ 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);
 
-- 
2.7.4


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2023-02-22 10:56 [PATCH V2] bus: mhi: host: Avoid ringing EV DB if there is no elements to process Vivek Pernamitta

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