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[2/3] usb: dwc3: gadget: Ignore Update Transfer cmd params

Message ID 997d9ebf38c6bba920d4ee77bd8c77bf81978a55.1638240306.git.Thinh.Nguyen@synopsys.com (mailing list archive)
State Accepted
Commit a02a26eb0aeaa2859a8b2f182bd5b5f7228ee1fe
Headers show
Series usb: dwc3: gadget: Reduce register read/write operations | expand

Commit Message

Thinh Nguyen Nov. 30, 2021, 2:53 a.m. UTC 
The controller doesn't check for Update Transfer command parameters
DEPCMDPAR{0,1,2}. Writing to these registers is unnecessary. Ignoring
this improves performance slightly by removing the register write
delay.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
 drivers/usb/dwc3/gadget.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 00b3f19c4d3e..f66baaef8a40 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -331,9 +331,17 @@  int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
 		}
 	}
 
-	dwc3_writel(dep->regs, DWC3_DEPCMDPAR0, params->param0);
-	dwc3_writel(dep->regs, DWC3_DEPCMDPAR1, params->param1);
-	dwc3_writel(dep->regs, DWC3_DEPCMDPAR2, params->param2);
+	/*
+	 * For some commands such as Update Transfer command, DEPCMDPARn
+	 * registers are reserved. Since the driver often sends Update Transfer
+	 * command, don't write to DEPCMDPARn to avoid register write delays and
+	 * improve performance.
+	 */
+	if (DWC3_DEPCMD_CMD(cmd) != DWC3_DEPCMD_UPDATETRANSFER) {
+		dwc3_writel(dep->regs, DWC3_DEPCMDPAR0, params->param0);
+		dwc3_writel(dep->regs, DWC3_DEPCMDPAR1, params->param1);
+		dwc3_writel(dep->regs, DWC3_DEPCMDPAR2, params->param2);
+	}
 
 	/*
 	 * Synopsys Databook 2.60a states in section 6.3.2.5.6 of that if we're