linux-kernel - [PATCH net-next v3 5/6] net: ravb: Do not apply features to hardware if the interface is down

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Date: Tue, 13 Feb 2024 11:41:09 +0200
From: Claudiu <claudiu.beznea@...on.dev>
To: s.shtylyov@....ru,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	biju.das.jz@...renesas.com
Cc: netdev@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	claudiu.beznea@...on.dev,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: [PATCH net-next v3 5/6] net: ravb: Do not apply features to hardware if the interface is down

From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

Do not apply features to hardware if the interface is down. In case runtime
PM is enabled, and while the interface is down, the IP will be in reset
mode (as for some platforms disabling the clocks will switch the IP to
reset mode, which will lead to losing register contents) and applying
settings in reset mode is not an option. Instead, cache the features and
apply them in ravb_open() through ravb_emac_init().

To avoid accessing the hardware while the interface is down
pm_runtime_active() check was introduced. Along with it the device runtime
PM usage counter has been incremented to avoid disabling the device clocks
while the check is in progress (if any).

Commit prepares for the addition of runtime PM.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
---

Changes in v3:
- updated patch title and description
- updated patch content due to patch 4/6

Changes in v2:
- fixed typo in patch description
- adjusted ravb_set_features_gbeth(); didn't collect the Sergey's Rb
  tag due to this 

Changes since [2]:
- use pm_runtime_get_noresume() and pm_runtime_active() and updated the
  commit message to describe that
- fixed typos
- s/CSUM/checksum in patch title and description

Changes in v3 of [2]:
- this was patch 20/21 in v2
- fixed typos in patch description
- removed code from ravb_open()
- use ndev->flags & IFF_UP checks instead of netif_running()

Changes in v2 of [2]:
- none; this patch is new


 drivers/net/ethernet/renesas/ravb_main.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index b3b91783bb7a..4dd0520dea90 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -2566,15 +2566,23 @@ static int ravb_set_features(struct net_device *ndev,
 {
 	struct ravb_private *priv = netdev_priv(ndev);
 	const struct ravb_hw_info *info = priv->info;
-	int ret;
+	struct device *dev = &priv->pdev->dev;
+	int ret = 0;
+
+	pm_runtime_get_noresume(dev);
+
+	if (!pm_runtime_active(dev))
+		goto out_set_features;
 
 	ret = info->set_feature(ndev, features);
 	if (ret)
-		return ret;
+		goto out_rpm_put;
 
+out_set_features:
 	ndev->features = features;
-
-	return 0;
+out_rpm_put:
+	pm_runtime_put_noidle(dev);
+	return ret;
 }
 
 static const struct net_device_ops ravb_netdev_ops = {
-- 
2.39.2