On 06.09.2024 23:19:51, Hamby, Jake (US) wrote: > If any error flags are set when bringing up the CAN device, e.g. due to > CAN bus traffic before initializing the device, when m_can_start is > called and interrupts are enabled, m_can_isr is called immediately, > which disables all CAN interrupts and calls napi_schedule. > > Because napi_enable isn't called until later in m_can_open, the call to > napi_schedule never schedules the m_can_poll callback and the device is > left with interrupts disabled and can't receive any CAN packets until > rebooted. This can be verified by running "cansend" from another device > before setting the bitrate and calling "ip link set up can0" on the test > device. Adding debug lines to m_can_isr shows it's called with flags > (IR_EP | IR_EW | IR_CRCE), which calls m_can_disable_all_interrupts and > napi_schedule, and then m_can_poll is never called. > > Move the call to napi_enable above the call to m_can_start to enable any > initial interrupt flags to be handled by m_can_poll so that interrupts > are reenabled. Add a call to napi_disable in the error handling section > of m_can_open, to handle the case where later functions return errors. > > Also, in m_can_close, move the call to napi_disable below the call to > m_can_stop to ensure all interrupts are handled when bringing down the > device. This race condition is much less likely to occur. > > While testing, I noticed that IR_TSW (timestamp wraparound) fires at > about 1 Hz, but the driver doesn't care about it. Add it to the list of > interrupts to disable in m_can_chip_config to reduce unneeded wakeups. > > Tested on a Microchip SAMA7G54 MPU. The fix should be applicable to any > SoC with a Bosch M_CAN controller. Thank you very much for your contribution! I believe you have solved the problem I was investigating last Friday. I still need to test it with your solution though. This patch does not contain your Signed-off-by [1]. Add it to your next patches; "git commit -s" will add it automatically. For this patch, you can reply and include it in your email! [1] https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin regards, Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung Nürnberg | Phone: +49-5121-206917-129 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-9 |
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