linux-kernel - Re: [PATCH printk v5 1/1] printk: extend console

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Message-ID: <b7c81f02-039e-e877-d7c3-6834728d2117@samsung.com>
Date:   Fri, 6 May 2022 08:43:02 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     John Ogness <john.ogness@...utronix.de>,
        Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-amlogic@...ts.infradead.org
Subject: Re: [PATCH printk v5 1/1] printk: extend console_lock for
 per-console locking

Hi John,

On 06.05.2022 00:33, John Ogness wrote:
> On 2022-05-05, John Ogness <john.ogness@...utronix.de> wrote:
>> I will go through and check if all access to AML_UART_CONTROL is
>> protected by port->lock.
> The startup() callback of the uart_ops is not called with the port
> locked. I'm having difficulties identifying if the startup() callback
> can occur after the console was already registered via meson_uart_init()
> and could be actively printing, but I see other serial drivers are
> protecting their registers in the startup() callback with the
> port->lock.
>
> Could you try booting the meson hardware with the following change? (And
> removing any previous debug changes I posted?)

Bingo! It looks that the startup() is called when getty initializes 
console. This fixed the issues observed on the Amlogic Meson based boards.

Feel free to add:

Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland