On 2/22/2023 4:43 AM, Vivek Pernamitta wrote:
Avoid ringing Event DB if there is no elements to process.
This is almost exactly identical to $SUBJECT and therefore redundant.
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.
I think that you could be more clear on why this is a problem that
should be addressed. Perhaps add a sentence like "These doorbell events
needlessly interrupt the MHI device to checked for ring elements when
there are none."
With the commit text updated, you can add
Reviewed-by: Jeffrey Hugo <quic_jhugo@xxxxxxxxxxx>
Signed-off-by: Vivek Pernamitta <quic_vpernami@xxxxxxxxxxx>
---
changes since v3:
- Updating commit text for multiple versions of patches.
changes since v2:
- Updated comments in code.
changes since v1:
- Add an check to avoid ringing EV DB in mhi_process_ctrl_ev_ring().
---
drivers/bus/mhi/host/main.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index df0fbfe..1bbdb75 100644
--- 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);
