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Message-ID: <CAK7LNAROoAhD=cFG6OdDTpP1xc8zoqbczF4mouv4d00kpORHJQ@mail.gmail.com> Date: Thu, 29 Oct 2015 14:21:45 +0900 From: Masahiro Yamada <yamada.masahiro@...ionext.com> To: Peter Hurley <peter@...leysoftware.com> Cc: linux-serial@...r.kernel.org, Vineet Gupta <Vineet.Gupta1@...opsys.com>, Kevin Cernekee <cernekee@...il.com>, Jiri Slaby <jslaby@...e.com>, Rob Herring <robh@...nel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org> Subject: Re: [PATCH v2 1/2] serial: 8250_early: do not save and restore IER in write callback 2015-10-28 23:36 GMT+09:00 Peter Hurley <peter@...leysoftware.com>: > On 10/27/2015 11:27 PM, Masahiro Yamada wrote: >> Hi Peter, >> >> 2015-10-27 22:54 GMT+09:00 Peter Hurley <peter@...leysoftware.com>: >>> Hi Masahiro, >>> >>> On 10/24/2015 12:17 AM, Masahiro Yamada wrote: >>>> The IER has already been masked in early_serial8250_setup(), there is >>>> no reason to save and restore it every time early_serial8250_write() >>>> is called. >>>> >>>> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com> >>>> --- >>>> >>>> drivers/tty/serial/8250/8250_early.c | 12 ------------ >>>> 1 file changed, 12 deletions(-) >>>> >>>> diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c >>>> index 7aff3d8..559b681 100644 >>>> --- a/drivers/tty/serial/8250/8250_early.c >>>> +++ b/drivers/tty/serial/8250/8250_early.c >>>> @@ -99,20 +99,8 @@ static void __init early_serial8250_write(struct console *console, >>>> { >>>> struct earlycon_device *device = console->data; >>>> struct uart_port *port = &device->port; >>>> - unsigned int ier; >>>> - >>>> - /* Save the IER and disable interrupts preserving the UUE bit */ >>>> - ier = serial8250_early_in(port, UART_IER); >>>> - if (ier) >>>> - serial8250_early_out(port, UART_IER, ier & UART_IER_UUE); >>>> >>>> uart_console_write(port, s, count, serial_putc); >>> >>> >>> >>>> - >>>> - /* Wait for transmitter to become empty and restore the IER */ >>>> - wait_for_xmitr(port); >>> >>> This wait_for_xmitr() change needs to be in patch 2/2. >>> >> >> >> Why? > > Because if someone reports a regression bisected to this commit, > we won't know if the regression is because we're not saving/restoring IER > or because the transmitter is still running. > Good point. I will send v3. Thanks! -- Best Regards Masahiro Yamada -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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