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From:   Kevin Hilman <khilman@baylibre.com>
To:     Yu Tu <yu.tu@amlogic.com>, linux-serial@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Subject: Re: [PATCH V6 0/5] Use CCF to describe the UART baud rate clock
In-Reply-To: <cc3b971f-c630-4ce2-e6dd-c13bcba89d22@amlogic.com>
References: <20220118030911.12815-1-yu.tu@amlogic.com>
 <7hfspjqrn7.fsf@baylibre.com>
 <cc3b971f-c630-4ce2-e6dd-c13bcba89d22@amlogic.com>
Date:   Mon, 24 Jan 2022 11:58:04 -0800
Message-ID: <7hbl00ykhf.fsf@baylibre.com>
MIME-Version: 1.0
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Yu Tu <yu.tu@amlogic.com> writes:

> Hi Kevin,
> 	Thank you very much for your reply.
>
> On 2022/1/20 6:37, Kevin Hilman wrote:
>> [ EXTERNAL EMAIL ]
>> 
>> Hello,
>> 
>> Yu Tu <yu.tu@amlogic.com> writes:
>> 
>>> Using the common Clock code to describe the UART baud rate
>>> clock makes it easier for the UART driver to be compatible
>>> with the baud rate requirements of the UART IP on different
>>> meson chips. Add Meson S4 SoC compatible.
>> 
>> Could you describe how this was tested and on which SoCs?  There seem to
>> be some changes in this series that might affect previous SoCs.
>> 
> For me, the board starts normally and prints. My intention was to add 
> the S4 SOC UART compatible, but for the S4 our baud rate clock is 
> calculated at 12MHz by default.So a series of changes were made at your 
> suggestion.
>
> Since most SoCs are too old, I was able to find all the platforms myself 
> such as Meson6, Meson8, Meson8b, GXL and so on. I only tested it with 
> G12A and S4.But when I talked to Martin earlier he tried meson8b's log.
> The test patch is in the attachment.
>
> I have found that on some boards with this change, the initcall_debug 
> Uart driver takes longer to initialize. Running the stty command to 
> change the baud rate at the same time may cause a jam.

This kind of detail is important to document in the cover letter,
including a bit more detail on how to reproduce so that other can help
test or may have ideas for how to solve.

> I'd love to know what else you suggest.

I don't expect you to be able to test on all SoCs, but just to list what
SoCs and which boards you tested on.  This way, those who have other
boards can help test and we can have a better idea of how this was
tested before merging.

Thanks,

Kevin