linux-kernel - [PATCH net-next 3/6] net: ipa: use usleep

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Date:   Wed, 13 Jan 2021 11:15:29 -0600
From:   Alex Elder <elder@...aro.org>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     evgreen@...omium.org, bjorn.andersson@...aro.org,
        cpratapa@...eaurora.org, subashab@...eaurora.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net-next 3/6] net: ipa: use usleep_range()

The use of msleep() for small periods (less than 20 milliseconds) is
not recommended because the actual delay can be much different than
expected.

We use msleep(1) in several places in the IPA driver to insert short
delays.  Replace them with usleep_range calls, which should reliably
delay a period in the range requested.

Fixes: 650d1603825d8 ("soc: qcom: ipa: the generic software interface")
Signed-off-by: Alex Elder <elder@...aro.org>
---
 drivers/net/ipa/gsi.c          | 5 +++--
 drivers/net/ipa/ipa_endpoint.c | 4 ++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
index e5681a39b5fc6..93b143ba92be5 100644
--- a/drivers/net/ipa/gsi.c
+++ b/drivers/net/ipa/gsi.c
@@ -611,7 +611,8 @@ static void gsi_channel_reset_command(struct gsi_channel *channel)
 	struct device *dev = channel->gsi->dev;
 	enum gsi_channel_state state;
 
-	msleep(1);	/* A short delay is required before a RESET command */
+	/* A short delay is required before a RESET command */
+	usleep_range(USEC_PER_MSEC, 2 * USEC_PER_MSEC);
 
 	state = gsi_channel_state(channel);
 	if (state != GSI_CHANNEL_STATE_STOPPED &&
@@ -900,7 +901,7 @@ int gsi_channel_stop(struct gsi *gsi, u32 channel_id)
 		ret = gsi_channel_stop_command(channel);
 		if (ret != -EAGAIN)
 			break;
-		msleep(1);
+		usleep_range(USEC_PER_MSEC, 2 * USEC_PER_MSEC);
 	} while (retries--);
 
 	mutex_unlock(&gsi->mutex);
diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c
index 9f4be9812a1f3..688a3dd40510a 100644
--- a/drivers/net/ipa/ipa_endpoint.c
+++ b/drivers/net/ipa/ipa_endpoint.c
@@ -1378,7 +1378,7 @@ static int ipa_endpoint_reset_rx_aggr(struct ipa_endpoint *endpoint)
 	do {
 		if (!ipa_endpoint_aggr_active(endpoint))
 			break;
-		msleep(1);
+		usleep_range(USEC_PER_MSEC, 2 * USEC_PER_MSEC);
 	} while (retries--);
 
 	/* Check one last time */
@@ -1399,7 +1399,7 @@ static int ipa_endpoint_reset_rx_aggr(struct ipa_endpoint *endpoint)
 	 */
 	gsi_channel_reset(gsi, endpoint->channel_id, true);
 
-	msleep(1);
+	usleep_range(USEC_PER_MSEC, 2 * USEC_PER_MSEC);
 
 	goto out_suspend_again;
 
-- 
2.20.1