linux-kernel - Re: [PATCH v2 1/4] cxl: add a firmware update mechanism using the sysfs firmware loader

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Message-ID: <20230609120852.00003c6c@Huawei.com>
Date:   Fri, 9 Jun 2023 12:08:52 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     "Verma, Vishal L" <vishal.l.verma@...el.com>
CC:     "Jiang, Dave" <dave.jiang@...el.com>,
        "Schofield, Alison" <alison.schofield@...el.com>,
        "linux-cxl@...r.kernel.org" <linux-cxl@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        "Weight, Russell H" <russell.h.weight@...el.com>,
        "bwidawsk@...nel.org" <bwidawsk@...nel.org>,
        "Weiny, Ira" <ira.weiny@...el.com>,
        "dave@...olabs.net" <dave@...olabs.net>
Subject: Re: [PATCH v2 1/4] cxl: add a firmware update mechanism using the
 sysfs firmware loader

On Thu, 8 Jun 2023 20:26:43 +0000
"Verma, Vishal L" <vishal.l.verma@...el.com> wrote:

> On Thu, 2023-06-08 at 20:15 +0000, Verma, Vishal L wrote:
> >   
> > > > +
> > > > +       fwl = firmware_upload_register(THIS_MODULE, &cxlmd->dev,
> > > > +                                      dev_name(&cxlmd->dev),
> > > > +                                      &cxl_memdev_fw_ops, cxlds);
> > > > +       if (IS_ERR(fwl)) {
> > > > +               dev_err(&cxlmd->dev, "Failed to register firmware loader\n");
> > > > +               return PTR_ERR(fwl);  
> > > 
> > > It's called from probe only so could use dev_err_probe() for slight
> > > simplification.  
> > 
> > From what I can tell, this ends up looking like:
> > 
> >         fwl = firmware_upload_register(THIS_MODULE, dev, dev_name(dev),
> >                                        &cxl_memdev_fw_ops, cxlds);
> >         rc = dev_err_probe(dev, PTR_ERR(fwl),
> >                            "Failed to register firmware loader\n");
> >         if (rc)
> >                 return rc;
> > 
> > Is that what you meant? Happy to make the change if so.
> > 
> >   
> Actually I can't drop the IS_ERR() check - so unless I'm missing
> something, this doesn't look like much of a simplification:
> 
> 
> 	if (IS_ERR(fwl)) {
> 		rc = dev_err_probe(dev, PTR_ERR(fwl),
> 				   "Failed to register firmware loader\n");
> 		if (rc)
> 			return rc;
> 	}
> 

Ah. I replied to previous. It's simpler than that as you know rc != 0 as
it's IS_ERR(fwl)

dev_err_probe() does two helpful things over dev_err()
1. Handles stashing the debug messages for the deferred probe cases (not
   relevant here but harmless)
2. Returns the variable you pass in as second argument to allow
   return dev_err_probe()


Jonathan