Hi Geert, On Monday 09 Jan 2017 10:53:55 Geert Uytterhoeven wrote: > On Fri, Jan 6, 2017 at 1:30 PM, Laurent Pinchart wrote: > > On Friday 02 Dec 2016 13:35:10 Geert Uytterhoeven wrote: > >> If a UART has dedicated RTS/CTS pins, there are some issues: > >> 1. When changing hardware control flow, the new AUTORTS state is not > >> immediately reflected in the hardware, but only when RTS is raised. > >> However, the serial core doesn't call .set_mctrl() after > >> .set_termios(), hence AUTORTS may only become effective when the port > >> is closed, and reopened later. > >> Note that this problem does not happen when manually using stty to > >> change CRTSCTS, as AUTORTS will work fine on next open. > >> > >> 2. When hardware control flow is disabled (or AUTORTS is not yet > >> effective), changing any serial port configuration deasserts RTS, as > >> .set_termios() calls sci_init_pins(). > > > > Isn't this still a problem with this patch applied ? Calling > > sci_set_mctrl() should reconfigure the pins properly, but won't there be > > a short window during which the configuration will be wrong ? > > You mean in between the calls to sci_init_pins() and sci_set_mctrl()? That's what I mean, yes. > I don't think _de_asserting RTS for a few microseconds matters much, would > it? Asserting RTS wrongly would be worse. It's not the end of the world, but as you're trying to fix this issue, maybe it would be a good time to refactor the code properly and fix the core problem (.set_termios() calling sci_init_pins()) rather than working around it :-) -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
