[PATCH 5.15.y 4/6] xhci: dbc: Improve performance by removing delay in transfer event polling.

[Sasha Levin <sashal@kernel.org>]

From: Mathias Nyman <mathias.nyman@linux.intel.com>

[ Upstream commit 03e3d9c2bd85cda941b3cf78e895c1498ac05c5f ]

Queue event polling work with 0 delay in case there are pending transfers
queued up. This is part 2 of a 3 part series that roughly triples dbc
performace when using adb push and pull over dbc.

Max/min push rate after patches is 210/118 MB/s, pull rate 171/133 MB/s,
tested with large files (300MB-9GB) by Łukasz Bartosik

First performance improvement patch was commit 31128e7492dc
("xhci: dbc: add dbgtty request to end of list once it completes")

Cc: Łukasz Bartosik <ukaszb@chromium.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20241227120142.1035206-2-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: f3d12ec847b9 ("xhci: dbc: fix bogus 1024 byte prefix if ttyDBC read races with stall event")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/usb/host/xhci-dbgcap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
index 004e69f424860..ce56b9316e124 100644
--- a/drivers/usb/host/xhci-dbgcap.c
+++ b/drivers/usb/host/xhci-dbgcap.c
@@ -987,7 +987,7 @@ static void xhci_dbc_handle_events(struct work_struct *work)
 		/* set fast poll rate if there are pending data transfers */
 		if (!list_empty(&dbc->eps[BULK_OUT].list_pending) ||
 		    !list_empty(&dbc->eps[BULK_IN].list_pending))
-			poll_interval = 1;
+			poll_interval = 0;
 		break;
 	default:
 		dev_info(dbc->dev, "stop handling dbc events\n");
-- 
2.51.0