linux-kernel - [PATCHv4 3/4] net: cdc_ncm: record speed in status method

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Date:   Mon, 29 Mar 2021 19:16:50 -0700
From:   Grant Grundler <grundler@...omium.org>
To:     Oliver Neukum <oneukum@...e.com>, Jakub Kicinski <kuba@...nel.org>
Cc:     Roland Dreier <roland@...nel.org>, nic_swsd <nic_swsd@...ltek.com>,
        netdev <netdev@...r.kernel.org>,
        "David S . Miller" <davem@...emloft.net>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Grant Grundler <grundler@...omium.org>
Subject: [PATCHv4 3/4] net: cdc_ncm: record speed in status method

From: Oliver Neukum <oneukum@...e.com>

Until very recently, the usbnet framework only had support functions
for devices which reported the link speed by explicitly querying the
PHY over a MDIO interface. However, the cdc_ncm devices send
notifications when the link state or link speeds change and do not
expose the PHY (or modem) directly.

Support funtions (e.g. usbnet_get_link_ksettings_internal()) to directly
query state recorded by the cdc_ncm driver were added in a previous patch.

So instead of cdc_ncm spewing the link speed into the dmesg buffer,
record the link speed encoded in these notifications and tell the
usbnet framework to use the new functions to get link speed/state.
Link speed/state is now available via ethtool.

This is especially useful given all current RTL8156 devices emit
a connection/speed status notification every 32ms and this would
fill the dmesg buffer. This implementation replaces the one
recently submitted in de658a195ee23ca6aaffe197d1d2ea040beea0a2 :
   "net: usb: cdc_ncm: don't spew notifications"

v2: rebased on upstream
v3: changed variable names
v4: rewrote commit message

Signed-off-by: Oliver Neukum <oneukum@...e.com>
Tested-by: Roland Dreier <roland@...nel.org>
Signed-off-by: Grant Grundler <grundler@...omium.org>
---
 drivers/net/usb/cdc_ncm.c | 55 ++++++++++++---------------------------
 1 file changed, 17 insertions(+), 38 deletions(-)

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 2644234d4c4d..6f330c7dcad2 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -133,17 +133,17 @@ static void cdc_ncm_get_strings(struct net_device __always_unused *netdev, u32 s
 static void cdc_ncm_update_rxtx_max(struct usbnet *dev, u32 new_rx, u32 new_tx);
 
 static const struct ethtool_ops cdc_ncm_ethtool_ops = {
-	.get_link          = usbnet_get_link,
-	.nway_reset        = usbnet_nway_reset,
-	.get_drvinfo       = usbnet_get_drvinfo,
-	.get_msglevel      = usbnet_get_msglevel,
-	.set_msglevel      = usbnet_set_msglevel,
-	.get_ts_info       = ethtool_op_get_ts_info,
-	.get_sset_count    = cdc_ncm_get_sset_count,
-	.get_strings       = cdc_ncm_get_strings,
-	.get_ethtool_stats = cdc_ncm_get_ethtool_stats,
-	.get_link_ksettings      = usbnet_get_link_ksettings_mii,
-	.set_link_ksettings      = usbnet_set_link_ksettings_mii,
+	.get_link		= usbnet_get_link,
+	.nway_reset		= usbnet_nway_reset,
+	.get_drvinfo		= usbnet_get_drvinfo,
+	.get_msglevel		= usbnet_get_msglevel,
+	.set_msglevel		= usbnet_set_msglevel,
+	.get_ts_info		= ethtool_op_get_ts_info,
+	.get_sset_count		= cdc_ncm_get_sset_count,
+	.get_strings		= cdc_ncm_get_strings,
+	.get_ethtool_stats	= cdc_ncm_get_ethtool_stats,
+	.get_link_ksettings	= usbnet_get_link_ksettings_internal,
+	.set_link_ksettings	= NULL,
 };
 
 static u32 cdc_ncm_check_rx_max(struct usbnet *dev, u32 new_rx)
@@ -1826,33 +1826,9 @@ static void
 cdc_ncm_speed_change(struct usbnet *dev,
 		     struct usb_cdc_speed_change *data)
 {
-	uint32_t rx_speed = le32_to_cpu(data->DLBitRRate);
-	uint32_t tx_speed = le32_to_cpu(data->ULBitRate);
-
-	/* if the speed hasn't changed, don't report it.
-	 * RTL8156 shipped before 2021 sends notification about every 32ms.
-	 */
-	if (dev->rx_speed == rx_speed && dev->tx_speed == tx_speed)
-		return;
-
-	dev->rx_speed = rx_speed;
-	dev->tx_speed = tx_speed;
-
-	/*
-	 * Currently the USB-NET API does not support reporting the actual
-	 * device speed. Do print it instead.
-	 */
-	if ((tx_speed > 1000000) && (rx_speed > 1000000)) {
-		netif_info(dev, link, dev->net,
-			   "%u mbit/s downlink %u mbit/s uplink\n",
-			   (unsigned int)(rx_speed / 1000000U),
-			   (unsigned int)(tx_speed / 1000000U));
-	} else {
-		netif_info(dev, link, dev->net,
-			   "%u kbit/s downlink %u kbit/s uplink\n",
-			   (unsigned int)(rx_speed / 1000U),
-			   (unsigned int)(tx_speed / 1000U));
-	}
+	/* RTL8156 shipped before 2021 sends notification about every 32ms. */
+	dev->rx_speed = le32_to_cpu(data->DLBitRRate);
+	dev->tx_speed = le32_to_cpu(data->ULBitRate);
 }
 
 static void cdc_ncm_status(struct usbnet *dev, struct urb *urb)
@@ -1878,6 +1854,9 @@ static void cdc_ncm_status(struct usbnet *dev, struct urb *urb)
 		 * USB_CDC_NOTIFY_NETWORK_CONNECTION notification shall be
 		 * sent by device after USB_CDC_NOTIFY_SPEED_CHANGE.
 		 */
+		/* RTL8156 shipped before 2021 sends notification about
+		 * every 32ms. Don't forward notification if state is same.
+		 */
 		if (netif_carrier_ok(dev->net) != !!event->wValue)
 			usbnet_link_change(dev, !!event->wValue, 0);
 		break;
-- 
2.30.1