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SubjectRe: [PATCH v2 6/6] lib/vsprintf: Add %pfw conversion specifier for printing fwnode names
On Tue 2019-03-26 15:24:50, Andy Shevchenko wrote:
> On Tue, Mar 26, 2019 at 02:11:35PM +0100, Rasmus Villemoes wrote:
> > On 26/03/2019 13.41, Sakari Ailus wrote:
> > > Add support for %pfw conversion specifier (with "f" and "P" modifiers) to
> > > support printing full path of the node, including its name ("f") and only
> > > the node's name ("P") in the printk family of functions. The two flags
> > > have equivalent functionality to existing %pOF with the same two modifiers
> > > ("f" and "P") on OF based systems. The ability to do the same on ACPI
> > > based systems is added by this patch.
>
> > > + for (pass = false; strspn(fmt, modifiers); fmt++, pass = true) {
> > > + if (pass) {
> > > + if (buf < end)
> > > + *buf = ':';
> > > + buf++;
> > > + }
> > > +
> > > + switch (*fmt) {
> > > + case 'f': /* full_name */
> > > + buf = fwnode_gen_full_name(fwnode, buf, end);
> > > + break;
> > > + case 'P': /* name */
> > > + buf = string(buf, end, fwnode_get_name(fwnode),
> > > + str_spec);
> > > + break;
> > > + default:
> > > + break;
> > > + }
> > > + }
> >
> > This seems awfully complicated. Why would anyone ever pass more than one
> > of 'f' and 'P'? Why not just
> >
> > switch(*fmt) {
> > case 'P':
> > ...
> > case 'f':
> > default:
> > ...
> > }
> >
> > which avoids the loop and the strcspn. Or, drop the default: case and
> > don't have logic at all for falling back to 'f' if neither is present.
> >
> > > + return widen_string(buf, buf - buf_start, end, spec);
> > > +}
>
> My point as well (as per sent comments against previous version).
> Sakari, can you add test cases at the same time?
>
> > > return device_node_string(buf, end, ptr, spec, fmt + 1);
>
> > > + return fwnode_string(buf, end, ptr, spec, fmt + 1);
> >
> > Why not pass fmt+2; we know that fmt+1 points at a 'w'. Just to avoid
> > doing the fmt++ inside fwnode_string().
>
> I guess in order to be consistent with existing %pOF case. But wouldn't be
> better to fix %pOF for that sooner or later?

Good question. Are there any %pOF users that would want to use the for
cycle and printk more values by single %pOF? Would the output be human
readable without any delimiters or words around?

Best Regards,
Petr

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