On Thu, Oct 03, 2024 at 01:10:47PM -0700, Doug Anderson wrote:
On Tue, Oct 1, 2024 at 5:51 AM Johan Hovold johan+linaro@kernel.org wrote:
@@ -1179,6 +1179,11 @@ static int qcom_geni_serial_startup(struct uart_port *uport) if (ret) return ret; }
uart_port_lock_irq(uport);qcom_geni_serial_start_rx(uport);uart_port_unlock_irq(uport);I _think_ you don't need the locking here. The documentation for the "startup" callback say:
- Interrupts: globally disabled.
Heh, yeah, that comment dates back to 2002 and probably wasn't even correct back then.
This function is called with the port mutex held (and interrupts enabled), and I need to take the port lock to serialise against the console code.
Other than that, this looks reasonable to me. I seem to recall previous discussions where _someone_ was relying on the qcom_geni_serial_start_rx() at the end of termios for some reason (which always felt like a bad design), but I can't find those old discussions. I suspect that the fact that you've added the start_rx in startup() is what we needed.
Yeah, I tried to find a reason for why things were done this way, but it was probably just copied from the vendor driver. The hardware doesn't seem to require stopping rx in set_termios() (and tx is not stopped anyway), which could otherwise have been a reason.
Johan