Re: [PATCH v2] staging: greybus: replace PTR_ERR() with %pe in error messages

[Yalagada Pavan Kumar <pavankumaryalagada@gmail.com>]

On Tue, Oct 13, 2026 at 03:11:51PM -0500, Alex Elder wrote:
> On 10/12/26 9:24 PM, pavankumaryalagada@gmail.com wrote:
> > From: Yalagada Pavan Kumar <pavankumaryalagada@gmail.com>
> > 
> > Use %pe to print error pointers directly and display their
> > error names.
> > 
> > Keep the other PTR_ERR() call because its return value is
> > needed for ret.
> > 
> > Signed-off-by: Yalagada Pavan Kumar <pavankumaryalagada@gmail.com>
> 
> 
> Generally I think what you're doing is OK.  It looks
> like %pe is better than just %d, because it prints
> the error *name* for the pointer-coded error.
> 
> But I have two general questions about this effort:
> 
> - There are other places in the Greybus code (even in
>   just the staging source files) where this exact same
>   thing could be done.  Why limit this to "fw-core.c" only?

I initially limited the change to "fw-core.c" because I was
focusing on the error messages in that file.

> 
> - Do you think that all Greybus error messages should be
>   converted to use %pe (passing ERR_PTR() if necessary)
>   instead of %d for showing the error number?

Using %pe prints the error name instead of just the
error number, which makes the error messages easier
to understand.

For example, the current message is:

	failed to create download connection (-12)

with %pe, it becomes:

	failed to create download connection (-ENOMEM)

I think the second message is easier to understand because
it shows the error name instead of just error number.

I also found other PTR_ERR() calls in Greybus. some of them
are used to return error codes and should remain unchanged.

For example, in fw-core.c:

	if (IS_ERR(connection)) {
		ret = PTR_ERR(connection);
		dev_err(&bundle->dev,
			"failed to create management connection (%pe)\n",
			connection);
		goto err_destroy_connections;
	}

Here, PTR_ERR(connection) is needed to store the error code in ret
for the error-handling path, while passing connection to %pe makes
the error message more readable.

> 
> I think your suggested change is a net positive, but
> doing it in some spots but not others means it is
> adding a bit of inconsistency.

I agree that similar cases elsewhere in Greybus are worth
checking to keep error reporting consistent. I will look
at the other Greybus files for cases where using %pe would
be appropriate.

Would you prefer me to extend this change to the other
relevant Greybus files, or keep this patch focused on
fw-core.c and submit a separate patch for the remaining
changes?

Thanks for the suggestions.

Pavan
> 
> 					-Alex
> 
> > ---
> > v2:
> > - Use %pe in the firmware management case, as suggested by Jeremy Clifton,
> >    to match the other cases.
> > 
> > v1: https://lore.kernel.org/outreachy/as0nhVbagZa8Birm@user/T/#t
> > ---
> >   drivers/staging/greybus/fw-core.c | 16 ++++++++--------
> >   1 file changed, 8 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/staging/greybus/fw-core.c b/drivers/staging/greybus/fw-core.c
> > index 2016a74f137f..78321be80013 100644
> > --- a/drivers/staging/greybus/fw-core.c
> > +++ b/drivers/staging/greybus/fw-core.c
> > @@ -93,8 +93,8 @@ static int gb_fw_core_probe(struct gb_bundle *bundle,
> >   			if (IS_ERR(connection)) {
> >   				ret = PTR_ERR(connection);
> >   				dev_err(&bundle->dev,
> > -					"failed to create management connection (%d)\n",
> > -					ret);
> > +					"failed to create management connection (%pe)\n",
> > +					connection);
> >   				goto err_destroy_connections;
> >   			}
> > @@ -112,8 +112,8 @@ static int gb_fw_core_probe(struct gb_bundle *bundle,
> >   			connection = gb_connection_create(bundle, cport_id,
> >   							  gb_fw_download_request_handler);
> >   			if (IS_ERR(connection)) {
> > -				dev_err(&bundle->dev, "failed to create download connection (%ld)\n",
> > -					PTR_ERR(connection));
> > +				dev_err(&bundle->dev, "failed to create download connection (%pe)\n",
> > +					connection);
> >   			} else {
> >   				fw_core->download_connection = connection;
> >   			}
> > @@ -131,8 +131,8 @@ static int gb_fw_core_probe(struct gb_bundle *bundle,
> >   			connection = gb_connection_create(bundle, cport_id,
> >   							  NULL);
> >   			if (IS_ERR(connection)) {
> > -				dev_err(&bundle->dev, "failed to create SPI connection (%ld)\n",
> > -					PTR_ERR(connection));
> > +				dev_err(&bundle->dev, "failed to create SPI connection (%pe)\n",
> > +					connection);
> >   			} else {
> >   				fw_core->spi_connection = connection;
> >   			}
> > @@ -149,8 +149,8 @@ static int gb_fw_core_probe(struct gb_bundle *bundle,
> >   			connection = gb_connection_create(bundle, cport_id,
> >   							  NULL);
> >   			if (IS_ERR(connection)) {
> > -				dev_err(&bundle->dev, "failed to create Authentication connection (%ld)\n",
> > -					PTR_ERR(connection));
> > +				dev_err(&bundle->dev, "failed to create Authentication connection (%pe)\n",
> > +					connection);
> >   			} else {
> >   				fw_core->cap_connection = connection;
> >   			}
>