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drivers: mttcan: fix bus-off restart txfer

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[Issue]: CAN freezes/stops to send messages after restart from bus-off state.
Throws following log from kernel: "write: No buffer space available"

[Reason]: When message txfer starts, tx_object (which keeps track of active tx)
gets filled. If CAN goes to bus-off state, txfer remains incomplete for some
messages. In such case, tx_object bits will not get cleared. It will stop
adding more messages in controller RAM.

Along with tx_object, from network layer, there are socket echo buffers.
When CAN is initialized and up on network, netif_start_queue is pushed to start
transmission. When msg txfer starts, socket buffer gets filled and freed only
when txfer completes. During bus-off, since network queue remains ON, all the
queued msgs get filled in socket buffers and does not allow upcoming msgs.
Therefore we see "write: No buffer space available".

[Fix]: Clear tx_object when device goes to bus-off state and stop network queue.
Start network queue again during restart from bus-off.

Bug 4438223

Change-Id: I3cbc6529a90f357372c8b0095bdce4217b133e9b
Signed-off-by: Shubhi Garg <shgarg@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3142091
(cherry picked from commit f902d95962)
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3144103
Reviewed-by: Bibek Basu <bbasu@nvidia.com>
GVS: buildbot_gerritrpt <buildbot_gerritrpt@nvidia.com>
This commit is contained in:
Shubhi Garg
2024-05-21 14:23:13 +05:30
committed by Jon Hunter
parent 7af5789560
commit 21a95b938b
1 changed files with 4 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/net/can/mttcan/native/m_ttcan_linux.c
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@@ -1,6 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (c) 2022-2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
* Copyright (c) 2022-2024, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
*/
#include <nvidia/conftest.h>
@@ -483,7 +483,8 @@ static int mttcan_state_change(struct net_device *dev,
*/
ttcan_set_intrpts(priv->ttcan, 0);
priv->can.can_stats.bus_off++;
priv->ttcan->tx_object = 0;
netif_stop_queue(dev);
netif_carrier_off(dev);
if (priv->can.restart_ms)
@@ -1092,6 +1093,7 @@ restart:
priv->can.can_stats.restarts++;
mttcan_start(dev);
netif_start_queue(dev);
netif_carrier_on(dev);
}