From: Dmitry Osipenko <digetx@gmail.com>
To: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
"Patrik John" <patrik.john@u-blox.com>
Cc: linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org,
ldewangan@nvidia.com, thierry.reding@gmail.com,
jonathan@nvidia.com, linux-serial@vger.kernel.org,
linux-tegra@vger.kernel.org
Subject: Re: [PATCH] serial: tegra: Fixes lower tolerance baud rate limit for older tegra chips introduced by d781ec21bae6
Date: Mon, 29 Nov 2021 15:33:56 +0300 [thread overview]
Message-ID: <7242bcd6-bb40-dc21-31b9-051429b89122@gmail.com> (raw)
In-Reply-To: <YaK9DwsgGr8eaMuX@qmqm.qmqm.pl>
28.11.2021 02:19, Michał Mirosław пишет:
> On Mon, Nov 22, 2021 at 01:44:26PM +0100, Patrik John wrote:
>> The current implementation uses 0 as lower limit for the baud rate tolerance which contradicts the initial commit description (https://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux.git/commit/drivers/tty/serial/serial-tegra.c?h=for-next&id=d781ec21bae6ff8f9e07682e8947a654484611f5) of +4/-4% tolerance for older tegra chips other than Tegra186 and Tegra194.
>> This causes issues on UART initilization as soon as the actual baud rate clock is slightly lower than required which we have seen on the Tegra124-based Toradex Apalis TK1 which also uses tegra30-hsuart as compatible in the DT serial node (for reference line 1540ff https://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux.git/tree/arch/arm/boot/dts/tegra124-apalis-v1.2.dtsi?h=for-next)
>>
>> The standard baud rate tolerance limits are also stated in the tegra20-hsuart driver description (https://www.kernel.org/doc/Documentation/devicetree/bindings/serial/nvidia%2Ctegra20-hsuart.txt).
>>
>> The previously introduced check_rate_in_range() always fails due to the lower limit set to 0 even if the actual baud rate is within the required -4% tolerance.
>>
> [...]
>
> I have a same patch waiting in my tree [1]. Feel free to use the commit
> message and to add:
>
> Reviewed-and-tested-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
>
> [1] https://rere.qmqm.pl/git/?p=linux;a=commitdiff;h=b658dcd83d0db777410fe960721193d35a38115a
The Reviewed-and-tested-by isn't a valid tag, should be two separate tags:
Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Tested-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
next prev parent reply other threads:[~2021-11-29 13:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-22 12:44 Patrik John
2021-11-22 13:01 ` Greg KH
2021-11-27 23:19 ` Michał Mirosław
2021-11-29 12:33 ` Dmitry Osipenko [this message]
2021-11-29 12:32 ` Dmitry Osipenko
2021-11-29 12:36 ` Dmitry Osipenko
2021-11-30 12:17 ` Dmitry Osipenko
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