Re: [RFC PATCH v2 0/4] staging: vc04: Drop custom logging

[Umang Jain]

Hi Stefan,

On 9/17/23 9:06 PM, Stefan Wahren wrote:
> 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.

+1
> > > 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.

Can't the state dump be printed to dev_dbg() ? Will it pollute the 
kernel log?  Having debugfs for a single dump doesn't seem worthwhile if 
the state dump can be incorporated to dev_dbg() too.
> > > 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.

Thanks Dan.
> > regards,
> > dan carpenter