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From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Stefan Agner <stefan@agner.ch>
Cc: gregkh@linuxfoundation.org, jslaby@suse.com,
	linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] serial: imx: fix cached UCR2 read on software reset
Date: Fri, 20 Apr 2018 08:03:15 +0200	[thread overview]
Message-ID: <20180420060315.ob6eygfcibwq7f24@pengutronix.de> (raw)
In-Reply-To: <581f0f26d7191aa3355a6c63b531f876@agner.ch>

Hello Stefan,

On Thu, Apr 19, 2018 at 11:37:23PM +0200, Stefan Agner wrote:
> On 16.04.2018 17:35, Stefan Agner wrote:
> > To reset the UART the SRST needs be cleared (low active). According
> > to the documentation the bit will remain active for 4 module clocks
> > until it is cleared (set to 1).
> > 
> > Hence the real register need to be read in case the cached register
> > indcates that the SRST bit is zero.
> > 
> > This bug lead to wrong baudrate because the baud rate register got
> > restored before reset completed in imx_flush_buffer.
> 
> Given that you reviewed my other patch rather quickly, you might have
> overlooked this one?

no I didn't, still the ping was justified. I didn't look into it at once
because I didn't feel like opening the refman.
 
> Since it is a regression, this should go into v4.17 still...

That's right,

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

I wonder what is different on your side that made it break. I didn't see
any breakage and tested that on a handful of different machines.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

  reply	other threads:[~2018-04-20  6:03 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-16 15:35 Stefan Agner
2018-04-19 21:37 ` Stefan Agner
2018-04-20  6:03   ` Uwe Kleine-König [this message]
2018-04-20  8:22     ` Stefan Agner
2018-04-19 22:15 ` Fabio Estevam

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