Re: [PATCH v2] drm/xe/pcode: Convert unsupported commands to debug level

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

On Mon, Nov 17, 2025 at 02:26:16PM +0000, Gupta, Anshuman wrote:
> 
> 
> > -----Original Message-----
> > From: Intel-xe <intel-xe-bounces@lists.freedesktop.org> On Behalf Of Raag
> > Jadav
> > Sent: Wednesday, November 12, 2025 8:15 PM
> > To: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: De Marchi, Lucas <lucas.demarchi@intel.com>; Vivi, Rodrigo
> > <rodrigo.vivi@intel.com>; intel-xe@lists.freedesktop.org; Tauro, Riana
> > <riana.tauro@intel.com>; Brost, Matthew <matthew.brost@intel.com>;
> > Wajdeczko, Michal <Michal.Wajdeczko@intel.com>; Nilawar, Badal
> > <badal.nilawar@intel.com>
> > Subject: Re: [PATCH v2] drm/xe/pcode: Convert unsupported commands to
> > debug level
> >
> > On Fri, Nov 07, 2025 at 03:16:18PM +0200, Ville Syrjälä wrote:
> > > On Fri, Nov 07, 2025 at 06:03:28AM -0600, Lucas De Marchi wrote:
> > > > On Fri, Nov 07, 2025 at 11:26:11AM +0530, Raag Jadav wrote:
> > > > > If the device is running older pcode firmware, it is possible that
> > > > > newer mailbox commands are not supported by it. The respective
> > > > > functionality isn't useful in that case but neither is error
> > > > > logging, since it doesn't particularly signify anything wrong with
> > > > > pcode firmware or device as a whole. This is useful in cases where
> > > > > we want to make a decision on driver functionality based on pcode
> > > > > return codes and a bit simpler design choice compared to other
> > > > > solutions like checking pcode firmware version, which comes with
> > > > > additional complexity of binding every single command to a
> > > > > specific version and deems pcode commands useless in case driver fails
> > to obtain it for reasons unrelated to pcode.
> > > >
> > > > yeah.. I don't think we should regress the support in new kernel
> > > > versions and require users to update their IFWI. However dropping
> > > > the error message here also makes it harder to find cases in which
> > > > we are indeed using a wrong command.
> > > >
> > > > I'd say to decide on err vs dbg based on CONFIG_DRM_XE_DEBUG so
> > > > developers can still see the error and take the right action.
> > >
> > > I think the caller should decide this. If it's explicitly probing for
> > > something that may or may not exist then use  dbg(), otherwise use
> > > err().
> >
> > I like the idea. What I'm afraid is that once we open that door it'll probably
> > start getting abused.
> @Rodrigo Vivi What is your opinion I here, I really like the idea suggested by Ville here.

I like Ville's idea here as well.
As long as the default is err and we downgrade to dbg on specific cases where
caller knows that the compatibility is limited.

> Thanks,
> Anshuman
> >
> > So rather we can check if we're really *in* probe()? Wait for a v3.
> >
> > Raag