Message-ID: <edd6f6ad-f06f-5871-a3bb-da18e114c135@i2se.com>
Date:   Sun, 20 Jun 2021 15:28:43 +0200
From:   Stefan Wahren <stefan.wahren@...e.com>
To:     Ojaswin Mujoo <ojaswin98@...il.com>, nsaenz@...nel.org
Cc:     gregkh@...uxfoundation.org, arnd@...db.de,
        dan.carpenter@...cle.com, phil@...pberrypi.com,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/5] vchiq: Patch to separate platform and cdev code

Hi Ojaswin,

Am 20.06.21 um 14:55 schrieb Ojaswin Mujoo:
> Hello,
>
> This patchset adderesses the TODO item number 10 specified at:
>
>     drivers/staging/vc04-services/interface/TODO
>
> For reference, the task is:
>
>     10) Reorganize file structure: Move char driver to it's own file and join
>     both platform files
>
>     The cdev is defined alongside with the platform code in vchiq_arm.c. It
>     would be nice to completely decouple it from the actual core code. For
>     instance to be able to use bcm2835-audio without having /dev/vchiq created.
>     One could argue it's better for security reasons or general cleanliness. It
>     could even be interesting to create two different kernel modules, something
>     the likes of vchiq-core.ko and vchiq-dev.ko. This would also ease the
>     upstreaming process.
>
> As Stefan suggested in the last revision, I have split the commits into
> more finer parts for ease of readability and maintainability. I have
> also added 2 more patches to define a KConfig entry for vchiq cdev, and
> to merge the code in vchiq_2835_arm.c to vchiq_arm.c
>
> A summary of the patches is now as follows:
>
> - Patch 1: Move cdev init code into a function
> - Patch 2: Shift some devlarations from vchiq_arm.c to vchiq_arm.h for
>            sharing
> - Patch 3: Move vchiq cdev init code from vchiq_arm.c into vchiq_dev.c
> - Patch 4: Decouple cdev code by defining a Kconfig entry to allow
>            optional compilation of it.
> - Patch 5: Merge code in vchiq_2835_arm.c to vchiq_arm.c
>
> (More details can be found in the commit messages)
>
>
> NOTE:  This patchset is built against the raspberry pi mainline kernel at
> https://github.com/raspberrypi/linux/blob/rpi-5.10.y, and has been
> tested on Raspberry Pi 3B+
please don't do this, because it's a waste of time. Greg can only apply
patches against the mainline kernel and the patches must be tested with
the mainline kernel. Additionally i've sent a lot of patches recently
which are not applied against the vendor tree.
>
> At this point, I have some questions and ideas and would like to hear your
> thoughts and suggestions on them:
>
> 1. So as mentioned, I have built this against the raspberry pi kernel,
>    since I was not able to figure out a way to build the vanilla
>    mainline kernel for Raspberry Pi. However, I understand that since
>    this will be applied to the mainline, I need to make sure it is
>    consistent with it.  

Can you please describe the issue in detail?

Or try this older guide [1]

Best regards
Stefan Wahren

[1] - https://gist.github.com/lategoodbye/c7317a42bf7f9c07f5a91baed8c68f75

>
>    Hence to confirm that, I tried to "git am" this patchset to the
>    mainline kernel but there are some merge conflicts in doing so. I
>    have an idea how to resolve most of them except the following:
>
>     - The mainline vchiq_arm.c differs from the one in rapberry pi
>       mainline which caused conflict in Patch 3.
>
>    I'm not sure which vchiq_arm.c to treat as the base for my patches.
>    The one in mainline? or the one in raspberry pi's git tree?
>
>
> 2. This question is more related to the next set of patches I'm
>    planning to submit. So the last thing left in this TODO is to
>    completely decouple vchiq platform and cdev code into 2 separate
>    modules and I am planning to do that in a different patchset. 
>
>    The approach I have in mind is to start by using EXPORT_SYMBOL to
>    export all the functions (and accessor functions for variables like
>    g_state) that would be required for cdev init. Majority of these
>    would be exported from vchiq_arm.c and vchiq_core.c, and will then be
>    used in vchiq-dev.ko. Is this the right way to approach this? 
>
> Thank you in advance for looking into this and best regards!
> Ojaswin
>
>
> Ojaswin Mujoo (5):
>   staging: vchiq: Refactor vchiq cdev code
>   staging: vchiq: Move certain declarations to vchiq_arm.h
>   staging: vchiq: Move vchiq char driver to its own file
>   staging: vchiq: Make creation of vchiq cdev optional
>   staging: vchiq: Combine vchiq platform code into single file
>
>  arch/arm/configs/bcm2709_defconfig            |    1 +
>  arch/arm/configs/bcm2711_defconfig            |    1 +
>  arch/arm/configs/bcmrpi_defconfig             |    1 +
>  drivers/staging/vc04_services/Kconfig         |   10 +
>  drivers/staging/vc04_services/Makefile        |    5 +-
>  .../interface/vchiq_arm/vchiq_2835_arm.c      |  651 -----
>  .../interface/vchiq_arm/vchiq_arm.c           | 2477 ++++++-----------
>  .../interface/vchiq_arm/vchiq_arm.h           |   79 +
>  .../interface/vchiq_arm/vchiq_dev.c           | 1488 ++++++++++
>  9 files changed, 2402 insertions(+), 2311 deletions(-)
>  delete mode 100644 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
>  create mode 100644 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_dev.c
>

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