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Date:   Sun, 17 Sep 2023 17:36:13 +0200
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Subject: Re: [RFC PATCH v2 0/4] staging: vc04: Drop custom logging
To:     Umang Jain <umang.jain@ideasonboard.com>,
        Dan Carpenter <dan.carpenter@linaro.org>
Cc:     linux-staging@lists.linux.dev,
        linux-arm-kernel@lists.infradead.org,
        linux-rpi-kernel@lists.infradead.org, linux-media@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Adrien Thierry <athierry@redhat.com>,
        Dan Carpenter <error27@gmail.com>,
        Dave Stevenson <dave.stevenson@raspberrypi.com>,
        Kieran Bingham <kieran.bingham@ideasonboard.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Phil Elwell <phil@raspberrypi.com>
References: <20230913185528.770634-1-umang.jain@ideasonboard.com>
 <1d54715d-25f9-4937-bdff-de0136c95fe8@kadam.mountain>
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From:   Stefan Wahren <stefan.wahren@i2se.com>
In-Reply-To: <1d54715d-25f9-4937-bdff-de0136c95fe8@kadam.mountain>
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Precedence: bulk

Hi,

Am 14.09.23 um 08:35 schrieb Dan Carpenter:
> On Thu, Sep 14, 2023 at 12:25:24AM +0530, Umang Jain wrote:
>> Hello,
>>
>> This series attempts to restart the discussion on custom logging used
>> in VC04. In the last feedback gathered in [1] it seems that the logging
>> would rather be moved to use dynamic debug. The series tries to move
>> in that direction.
>>
>> The elephant in the room is the ability of turning on/off log levels,
>> which this series just drops. Compensated by a crude strings
>> ("error", "warning", "info"... etc) for easier grepping.
>>
>> The log category are also just strings (which probably can be transformed
>> to dynamic debug class names moving forwards?).
>>
>> To move forwards, I would like feedback on the broader direction.
>> There are couple of TODOs in each of the patch (summarised in commit
>> messages) which require case-by-case discussion.
>>
>> Additional high-level questions to move forwards:
>> 1. Is loss of log levels by moving to dynamic debug, is actually a
>>     concern? Is dynamic debug a valid replacement?
> 
> Dynamic debug is honestly going to be an improvement.  I guess, Greg and
> I said this back in Jan.
> 
>> 2. Whether debugfs should be dropped as well, found vestigial in [2]
> 
> Yes. The "vchiq/log" should be removed.  Ideally as part of this
> patchset so it's easier to understand.

Yes, but please do not remote vchiq_debugfs entirely. I'm working on a 
patch to move the state dump (debug feature) from the character device 
/dev/vchiq to debugfs /sys/kernel/debug/vchiq/dump_state.

> 
>> 3. whether vchiq_log_trace() should actually be tracing support for VC04
> 
> That can be done later if people want.  No need to discuss it now.
> 
> regards,
> dan carpenter
>