linux-kernel - Re: [PATCH v5 2/7] can: bittiming: allow TDC{V,O} to be zero and add can_tdc_const::tdc{v,o,f}

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Date:   Tue, 17 Aug 2021 10:12:44 +0900
From:   Vincent MAILHOL <mailhol.vincent@...adoo.fr>
To:     Marc Kleine-Budde <mkl@...gutronix.de>
Cc:     linux-can <linux-can@...r.kernel.org>,
        Stefan Mätje <Stefan.Maetje@....eu>,
        netdev <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 2/7] can: bittiming: allow TDC{V,O} to be zero and add can_tdc_const::tdc{v,o,f}_min

Hi Marc,

This patch fixes the bug you just encountered: having both TDC_AUTO
and TDC_MANUAL set at the same time. I also cleaned all garbage
data in struct can_tdc because that was trivial.

This patch is meant to be squashed into:
commit ca7200319a90 ("can: netlink: add interface for CAN-FD
Transmitter Delay Compensation (TDC)")

For now, I am just sharing it here so that you can continue your
testing. I will resend the full series after we finish current
ongoing discussion.

Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
---
 drivers/net/can/dev/netlink.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index f05745c96b9c..d8cefe7d354c 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -204,6 +204,7 @@ static int can_changelink(struct net_device *dev,
struct nlattr *tb[],
         }
     }

+    priv->ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
     if (data[IFLA_CAN_CTRLMODE]) {
         struct can_ctrlmode *cm;
         u32 ctrlstatic;
@@ -239,8 +240,6 @@ static int can_changelink(struct net_device *dev,
struct nlattr *tb[],
             dev->mtu = CAN_MTU;
             memset(&priv->data_bittiming, 0,
                    sizeof(priv->data_bittiming));
-            memset(&priv->tdc, 0, sizeof(priv->tdc));
-            priv->ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
         }

         tdc_mask = cm->mask & CAN_CTRLMODE_TDC_MASK;
@@ -326,6 +325,7 @@ static int can_changelink(struct net_device *dev,
struct nlattr *tb[],
         priv->termination = termval;
     }

+    memset(&priv->tdc, 0, sizeof(priv->tdc));
     if (data[IFLA_CAN_TDC]) {
         /* Use the provided TDC parameters */
         err = can_tdc_changelink(dev, data[IFLA_CAN_TDC], extack);
-- 
2.31.1