linux-kernel - Re: [PATCH 3/3] Serial: Separate out earlycon support

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Message-ID: <ab693e13-0478-5301-5ccb-9d8b1191afa1@codeaurora.org>
Date:   Mon, 7 Dec 2020 17:52:32 +0530
From:   Akash Asthana <akashast@...eaurora.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     bjorn.andersson@...aro.org, devicetree@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-serial@...r.kernel.org,
        mka@...omium.org, dianders@...omium.org,
        linux-kernel@...r.kernel.org, saravanak@...gle.com
Subject: Re: [PATCH 3/3] Serial: Separate out earlycon support

Hi Greg,

On 12/7/2020 2:41 PM, Greg KH wrote:
> On Mon, Dec 07, 2020 at 02:17:27PM +0530, Akash Asthana wrote:
>> Separate out earlycon support from serial driver and remove it's
>> dependency on QUP wrapper driver.
>>
>> This enable us to manage earlycon independently and we can re-use the
>> same earlycon driver for android project which currently uses
>> downstream version of QUP drivers.
> What do you mean by "downstream" here?
>
>> Signed-off-by: Akash Asthana <akashast@...eaurora.org>
>> ---
>>   drivers/tty/serial/Kconfig              |   9 +
>>   drivers/tty/serial/Makefile             |   1 +
>>   drivers/tty/serial/qcom_geni_earlycon.c | 649 ++++++++++++++++++++++++++++++++
>>   drivers/tty/serial/qcom_geni_serial.c   |  97 -----
> So you are replacing 97 lines of code with 649 lines?  How is this
> benefiting anyone?
>
> confused,

We have 2 versions of QUP driver, upstream version(Present in linus 
tree, mostly used for chromium project) and downstream version(belong to 
vendor part of code in GKI design, used for all the other project).

There is need to enable geni earlycon in Google provided boot image for 
GKI to facilitate the debug until real console(belong to vendor code) is up.

Currently it won't be possible because geni earlycon cannot be enabled 
independently, it depends on upstream QUP wrapper driver 
(soc/qcom/qcom-geni-se.c) and upstream serial 
driver(serial/qcom_geni_serial.c).

With this patch I am trying to break any dependency btw earlycon hook 
and QUP kernel drivers, so it can be managed independently.

Regards,

Akash

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,\na Linux Foundation Collaborative Project