linux-kernel - [PATCH 1/2] mwifiex: pcie: use posted write to wake up firmware

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Message-Id: <20170112210232.18554-1-briannorris@chromium.org>
Date:   Thu, 12 Jan 2017 13:02:31 -0800
From:   Brian Norris <briannorris@...omium.org>
To:     Amitkumar Karwar <akarwar@...vell.com>,
        Nishant Sarmukadam <nishants@...vell.com>
Cc:     <linux-kernel@...r.kernel.org>, Kalle Valo <kvalo@...eaurora.org>,
        linux-wireless@...r.kernel.org, Cathy Luo <cluo@...vell.com>,
        Brian Norris <briannorris@...omium.org>
Subject: [PATCH 1/2] mwifiex: pcie: use posted write to wake up firmware

Depending on system factors (e.g., the PCIe link PM state), the first
read to wake up the Wifi firmware can take a long time. There is no
reason to use a (blocking, non-posted) read at this point, so let's just
use a write instead. Write vs. read doesn't matter functionality-wise --
it's just a dummy operation.

This has been shown to decrease the time spent blocking in this function
on a Rockchip RK3399 SoC.

Signed-off-by: Brian Norris <briannorris@...omium.org>
---
 drivers/net/wireless/marvell/mwifiex/pcie.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c b/drivers/net/wireless/marvell/mwifiex/pcie.c
index 66226c615be0..435ba879ef29 100644
--- a/drivers/net/wireless/marvell/mwifiex/pcie.c
+++ b/drivers/net/wireless/marvell/mwifiex/pcie.c
@@ -458,7 +458,6 @@ static void mwifiex_delay_for_sleep_cookie(struct mwifiex_adapter *adapter,
 /* This function wakes up the card by reading fw_status register. */
 static int mwifiex_pm_wakeup_card(struct mwifiex_adapter *adapter)
 {
-	u32 fw_status;
 	struct pcie_service_card *card = adapter->card;
 	const struct mwifiex_pcie_card_reg *reg = card->pcie.reg;
 
@@ -468,10 +467,10 @@ static int mwifiex_pm_wakeup_card(struct mwifiex_adapter *adapter)
 	if (reg->sleep_cookie)
 		mwifiex_pcie_dev_wakeup_delay(adapter);
 
-	/* Reading fw_status register will wakeup device */
-	if (mwifiex_read_reg(adapter, reg->fw_status, &fw_status)) {
+	/* Accessing fw_status register will wakeup device */
+	if (mwifiex_write_reg(adapter, reg->fw_status, 0)) {
 		mwifiex_dbg(adapter, ERROR,
-			    "Reading fw_status register failed\n");
+			    "Writing fw_status register failed\n");
 		return -1;
 	}
 
-- 
2.11.0.390.gc69c2f50cf-goog