linux-kernel - Re: [PATCH] serial/core: Initialize the console pm state

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Message-ID: <CAMuHMdWwEoK__-qTdUmzx6vJJSQ1+XdvL3nZukUX_RjM1tDVGA@mail.gmail.com>
Date:	Fri, 3 Oct 2014 14:22:47 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Kevin Hilman <khilman@...nel.org>
Cc:	Sudhir Sreedharan <ssreedharan@...sta.com>,
	linux-serial@...r.kernel.org, Greg KH <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	lkml <linux-kernel@...r.kernel.org>,
	Olof Johansson <olof@...om.net>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] serial/core: Initialize the console pm state

On Wed, Oct 1, 2014 at 7:27 PM, Kevin Hilman <khilman@...nel.org> wrote:
> On Sun, Sep 21, 2014 at 11:30 PM, Sudhir Sreedharan
> <ssreedharan@...sta.com> wrote:
>> For console devices having UART_CAP_SLEEP capability, the uart_pm_state has
>> to be initialized to UART_PM_STATE_ON. Otherwise the LCR regiser values
>> are reinitialized when uart_change_pm is called from uart_configure_port.
>>
>> Signed-off-by: Sudhir Sreedharan <ssreedharan@...sta.com>
>
> Multiple boot failures on ARM[1] were bisected down to this patch.
>
> How was this patch tested, and on which platforms?
>
> Also, the changelog states that this should be done only for
> UART_CAP_SLEEP, but the patch does it for every UART.
>
> Greg, I suggest this patch be dropped from tty-next until it has been
> better described and tested.
>
> Kevin
>
> [1] http://lists.linaro.org/pipermail/kernel-build-reports/2014-October/005550.html

Perhaps it should call "uart_change_pm(state, UART_PM_STATE_ON)"
instead, so the driver's .pm() method is called?

UART_CAP_SLEEP seems to be an 8250-only flag.

BTW, this was the first commit I reverted when I had an issue with a serial
console yesterday, but it didn't seem to have any influence (for me).

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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