Re: [Intel-gfx] [PATCH v3 1/3] drm: Stop spamming log with drm_cache message

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, Feb 01, 2022 at 09:41:33AM -0800, Lucas De Marchi wrote:
> On Tue, Feb 01, 2022 at 09:12:05AM -0800, Jose Souza wrote:
> > On Mon, 2022-01-31 at 08:59 -0800, Lucas De Marchi wrote:
> > > Only x86 and in some cases PPC have support added in drm_cache.c for the
> > > clflush class of functions. However warning once is sufficient to taint
> > > the log instead of spamming it with "Architecture has no drm_cache.c
> > > support" every few millisecond. Switch to WARN_ONCE() so we still get
> > > the log message, but only once, together with the warning. E.g:
> > > 
> > > 	------------[ cut here ]------------
> > > 	Architecture has no drm_cache.c support
> > > 	WARNING: CPU: 80 PID: 888 at drivers/gpu/drm/drm_cache.c:139 drm_clflush_sg+0x40/0x50 [drm]
> > > 	...
> > > 
> > > v2 (Jani): use WARN_ONCE() and keep the message previously on pr_err()
> > 
> > Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
> > 
> > But while at it, why not add a drm_device parameter to this function so we can use drm_WARN_ONCE()?
> > Anyways, it is better than before.
> 
> I thought about that, but it didn't seem justifiable because:
> 
> 1) drm_WARN_ONCE will basically add dev_driver_string() to the log.
> However the warning message here is basically helping the bootstrap of
> additional archs. They shouldn't be seen on anything properly supported.
> 
> 2) This seems all to be a layer below drm anyway and could even be used
> in places outside easy access to a drm pointer.
> 
> So, it seems the benefit of using the subsystem-specific drm_WARN_ONCE
> doesn't justify the hassle of changing the callers, possibly adding
> additional back pointers to have access to the drm device pointer.

Initially I had same feeling as Jose, but good points raised here.

Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> 
> thanks
> Lucas De Marchi