When sending packets as fast as possible using "cangen -g 0 -i -x", the
HI-3110 occasionally latches the interrupt pin high on completion of a
packet, but doesn't set the TXCPLT bit in the INTF register. The INTF
register contains 0x00 as if no interrupt has occurred. Even waiting
for a few milliseconds after the interrupt doesn't help.
Work around this apparent erratum by instead checking the TXMTY bit in
the STATF register ("TX FIFO empty"). We know that we've queued up a
packet for transmission if priv->tx_len is nonzero. If the TX FIFO is
empty, transmission of that packet must have completed.
Note that this is congruent with our handling of received packets, which
likewise gleans from the STATF register whether a packet is waiting in
the RX FIFO, instead of looking at the INTF register.
Cc: Mathias Duckeck <m.duckeck@kunbus.de>
Cc: Akshay Bhat <akshay.bhat@timesys.com>
Cc: Casey Fitzpatrick <casey.fitzpatrick@timesys.com>
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Akshay Bhat <akshay.bhat@timesys.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
hi3110_get_berr_counter() may run concurrently to the rest of the driver
but neglects to acquire the lock protecting access to the SPI device.
As a result, it and the rest of the driver may clobber each other's tx
and rx buffers.
We became aware of this issue because transmission of packets with
"cangen -g 0 -i -x" frequently hung. It turns out that agetty executes
->do_get_berr_counter every few seconds via the following call stack:
CPU: 2 PID: 1605 Comm: agetty
[<7f3f7500>] (hi3110_get_berr_counter [hi311x])
[<7f130204>] (can_fill_info [can_dev])
[<80693bc0>] (rtnl_fill_ifinfo)
[<806949ec>] (rtnl_dump_ifinfo)
[<806b4834>] (netlink_dump)
[<806b4bc8>] (netlink_recvmsg)
[<8065f180>] (sock_recvmsg)
[<80660f90>] (___sys_recvmsg)
[<80661e7c>] (__sys_recvmsg)
[<80661ec0>] (SyS_recvmsg)
[<80108b20>] (ret_fast_syscall+0x0/0x1c)
agetty listens to netlink messages in order to update the login prompt
when IP addresses change (if /etc/issue contains \4 or \6 escape codes):
https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/?id=e36deb6424e8
It's a useful feature, though it seems questionable that it causes CAN
bit error statistics to be queried.
Be that as it may, if hi3110_get_berr_counter() is invoked while a frame
is sent by hi3110_hw_tx(), bogus SPI transfers like the following may
occur:
=> 12 00 (hi3110_get_berr_counter() wanted to transmit
EC 00 to query the transmit error counter,
but the first byte was overwritten by
hi3110_hw_tx_frame())
=> EA 00 3E 80 01 FB (hi3110_hw_tx_frame() wanted to transmit a
frame, but the first byte was overwritten by
hi3110_get_berr_counter() because it wanted
to query the receive error counter)
This sequence hangs the transmission because the driver believes it has
sent a frame and waits for the interrupt signaling completion, but in
reality the chip has never sent away the frame since the commands it
received were malformed.
Fix by acquiring the SPI lock in hi3110_get_berr_counter().
I've scrutinized the entire driver for further unlocked SPI accesses but
found no others.
Cc: Mathias Duckeck <m.duckeck@kunbus.de>
Cc: Akshay Bhat <akshay.bhat@timesys.com>
Cc: Casey Fitzpatrick <casey.fitzpatrick@timesys.com>
Cc: Stef Walter <stefw@redhat.com>
Cc: Karel Zak <kzak@redhat.com>
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Akshay Bhat <akshay.bhat@timesys.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This patch adds support for the Holt HI-311x CAN controller. The HI311x
CAN controller is capable of transmitting and receiving standard data
frames, extended data frames and remote frames. The HI311x interfaces
with the host over SPI.
Datasheet: www.holtic.com/documents/371-hi-3110_v-rev-jpdf.do
Signed-off-by: Akshay Bhat <nodeax@gmail.com>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Lukas Wunner