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Subject: Re: [PATCH] serdev: Don't claim unsupported serial devices
To:     Punit Agrawal <punit1.agrawal@toshiba.co.jp>
Cc:     linux-serial@vger.kernel.org, linux-acpi@vger.kernel.org,
        linux-kernel@vger.kernel.org, nobuhiro1.iwamatsu@toshiba.co.jp,
        shrirang.bagul@canonical.com, stable@vger.kernel.org,
        Rob Herring <robh@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Johan Hovold <johan@kernel.org>
References: <20191218065646.817493-1-punit1.agrawal@toshiba.co.jp>
 <096046b6-324a-8496-8599-ed7e5ffc6e3c@redhat.com>
 <87eex1noak.fsf@kokedama.swc.toshiba.co.jp>
From:   Hans de Goede <hdegoede@redhat.com>
Message-ID: <a2e86d54-287a-16b4-3dac-9e3fe3dee753@redhat.com>
Date:   Thu, 19 Dec 2019 09:30:38 +0100
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Hi,

On 19-12-2019 01:37, Punit Agrawal wrote:
> Hans de Goede <hdegoede@redhat.com> writes:
> 
>> Hi,
>>
>> On 18-12-2019 07:56, Punit Agrawal wrote:
>>> Serdev sub-system claims all serial devices that are not already
>>> enumerated. As a result, no device node is created for serial port on
>>> certain boards such as the Apollo Lake based UP2. This has the
>>> unintended consequence of not being able to raise the login prompt via
>>> serial connection.
>>>
>>> Introduce a blacklist to reject devices that should not be treated as
>>> a serdev device. Add the Intel HS UART peripheral ids to the blacklist
>>> to bring back serial port on SoCs carrying them.
>>>
>>> Cc: stable@vger.kernel.org
>>> Signed-off-by: Punit Agrawal <punit1.agrawal@toshiba.co.jp>
>>> Cc: Rob Herring <robh@kernel.org>
>>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>>> Cc: Johan Hovold <johan@kernel.org>
>>> Cc: Hans de Goede <hdegoede@redhat.com>
>>
>> Thank you for addressing this long standing issue.
> 
> I am surprised there hasn't been more people complaining! Maybe even on
> x86 mainline isn't that widely used on development boards.

I think it is also a case of there not being that manu x86 development
boards.

Regards,

Hans