[PATCH] drm/komeda: Adds error event print functionality

[Lowry Li (Arm Technology China)]

Hi Sean,

On Thu, Jul 18, 2019 at 11:23:50AM -0400, Sean Paul wrote:
> On Thu, Jul 18, 2019 at 02:17:37PM +0100, Liviu Dudau wrote:
> > On Thu, Jun 27, 2019 at 04:10:36AM +0100, Lowry Li (Arm Technology China) wrote:
> 
> /snip
> 
> > > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
> > > index 647bce5..1462bac 100644
> > > --- a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
> > > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
> > > @@ -47,6 +47,8 @@ static irqreturn_t komeda_kms_irq_handler(int irq, void *data)
> > >  	memset(&evts, 0, sizeof(evts));
> > >  	status = mdev->funcs->irq_handler(mdev, &evts);
> > >  
> > > +	komeda_print_events(&evts);
> > 
> > Calling this function from the IRQ handler is a bad idea. We should use debugfs
> > if you really want to have a trace of the events, but I personally don't see
> > value in having this functionality in the kernel at all. You can expose the
> > value of the evts->global and evts->pipes[] as integers and decode that in
> > userspace or as a debugfs entry.
> 
> Alternatively, consider using kernel trace events. They allow you to selectively
> turn on/off certain events and also allow you to customize which data is
> recorded and how it's formatted. Seems like a good fit from the quick scan I've
> done.
> 
> Sean
>
Yes, finially we want to get both way, using kernel trace events and
meanwhile printing out the hardware detected errors, from which we can
know directly once the errors happened on the hardware.Like intel did,
in intel_cpu_fifo_underrun_irq_handler().
Thanks a lot.

Best Regards,
Lowry
> > 
> > Best regards,
> > Liviu
> > 
> > > +
> > >  	/* Notify the crtc to handle the events */
> > >  	for (i = 0; i < kms->n_crtcs; i++)
> > >  		komeda_crtc_handle_event(&kms->crtcs[i], &evts);
> > > -- 
> > > 1.9.1
> > > 
> > 
> > -- 
> > ====================
> > | I would like to |
> > | fix the world,  |
> > | but they're not |
> > | giving me the   |
> >  \ source code!  /
> >   ---------------
> >     ¯\_(ツ)_/¯
> 
> -- 
> Sean Paul, Software Engineer, Google / Chromium OS

-- 
Regards,
Lowry