From: Stefan Wahren <stefan.wahren@i2se.com>
To: Ojaswin Mujoo <ojaswin98@gmail.com>, nsaenz@kernel.org
Cc: gregkh@linuxfoundation.org, dan.carpenter@oracle.com,
phil@raspberrypi.com, bcm-kernel-feedback-list@broadcom.com,
linux-arm-kernel@lists.infradead.org,
linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/1] Request to review progress decoupling vchiq platform code
Date: Tue, 15 Jun 2021 00:06:14 +0200 [thread overview]
Message-ID: <2212368e-b597-b717-0d21-70b24322ca09@i2se.com> (raw)
In-Reply-To: <cover.1623698773.git.ojaswin98@gmail.com>
Hi,
Am 14.06.21 um 21:32 schrieb Ojaswin Mujoo:
> Greetings,
>
> I'm working on addressing item 10 of the following TODO list:
>
> 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.
>
>
> This patch is the first step towards decoupling the platform and the cdev code.
> It moves all the cdev related code from vchiq_arm.c to vchiq_dev.c. However, for
> now, I have aimed to keep the functionality untouched, hence the platform code
> still calls the cdev initialisation function, and isn't truly decoupled yet.
>
> The summary of the changes is as follows:
>
>
> * Definition of functions and variables shared by cdev and platform
> code are moved to vchiq_arm.h while declaration stays in vchiq_arm.c
>
> * Declaration and definition of functions and variables only used by
> cdev code are moved to vchiq_dev.c file.
>
> * Defined vchiq_deregister_chrdev() and vchiq_register_chrdev(..) in
> vchiq_dev.c which handle cdev creation and deletion. They are called by the
> platfrom code during probe().
looks like this should be 3 separate patches. So you have the pure move
at the end.
>
>
> I mainly wanted to put this patch out to see if I have the right idea of the
> task at hand and to ensure I'm heading into the right direction. I would love to
> hear your thoughts and suggestions on this. Once I have some feedback on this, I
> can accordingly work towards a newer version to completely decouple the code.
>
> Lastly, I had some questions related to the the task:
>
> 1. So regarding the following line in the TODO:
>
> "For instance to be able to use bcm2835-audio without having /dev/vchiq
> created."
>
> I was wondering about the possible ways to achieve this. Specifically, I was
> thinking of the following 2 ways:
>
> 1.1 Making a KConfig entry for Cdev creation, like CONFIG_VCHIQ_CDEV, and
> then do something like:
>
> vchiq_probe(..)
> {
> /* platform init code */
>
> #if defined(CONFIG_VCHIQ_CDEV)
>
> /* Call cdev register function */
>
> #endif
> }
A common pattern is to keep the calls, but have "empty" definitions of
the those functions in the header file in case CONFIG_VCHIQ_CDEV is not
defined.
>
> 1.2 The second approach is creating an entirely separate module for the cdev,
> as suggested in the TODO.
>
> So I'm just wondering what the right approach should be?
>
> 2. Second, I currently tested by installing my patches to a pi3 B+ and running
> `cat /dev/vchiq` to compare the output with the original kernel. Also, to
> see if the platform code works without the cdev code, I commented out the
> call to vchiq_register_cdev() and made sure the platform device (and
> children) was registered but the char device was not present. However, I'm
> not sure if these tests are comprehensive enough. What would be the right way
> to test my changes?
Sounds okay, but a functional test is still necessary (tool is provided
by Raspberry Pi OS):
vchiq_test -f 10
vchiq_test -p 10
Regards
Stefan
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-06-14 22:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-14 19:32 [PATCH 0/1] Request to review progress decoupling vchiq platform code Ojaswin Mujoo
2021-06-14 19:33 ` [PATCH 1/1] staging: vchiq: Move vchiq char driver to its own file Ojaswin Mujoo
2021-06-14 22:06 ` Stefan Wahren [this message]
2021-06-15 17:10 ` [PATCH 0/1] Request to review progress decoupling vchiq platform code Ojaswin Mujoo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2212368e-b597-b717-0d21-70b24322ca09@i2se.com \
--to=stefan.wahren@i2se.com \
--cc=bcm-kernel-feedback-list@broadcom.com \
--cc=dan.carpenter@oracle.com \
--cc=gregkh@linuxfoundation.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-staging@lists.linux.dev \
--cc=nsaenz@kernel.org \
--cc=ojaswin98@gmail.com \
--cc=phil@raspberrypi.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).