Re: [PATCH v2 4/6] drivers: soc: xilinx: Fix error message on SGI registration failure

[Greg KH]

On Wed, Oct 04, 2023 at 12:48:25PM +0000, Buddhabhatti, Jay wrote:
> Hi Greg,
> 
> > -----Original Message-----
> > From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Sent: Wednesday, October 4, 2023 5:45 PM
> > To: Buddhabhatti, Jay <jay.buddhabhatti@xxxxxxx>
> > Cc: Simek, Michal <michal.simek@xxxxxxx>; Shah, Tanmay
> > <tanmay.shah@xxxxxxx>; Manne, Nava kishore
> > <nava.kishore.manne@xxxxxxx>; Levinsky, Ben <ben.levinsky@xxxxxxx>;
> > robh@xxxxxxxxxx; dhaval.r.shah@xxxxxxx; marex@xxxxxxx; Shaikh, Izhar
> > Ameer <izhar.ameer.shaikh@xxxxxxx>; arnd@xxxxxxxx;
> > ruanjinjie@xxxxxxxxxx; mathieu.poirier@xxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > Subject: Re: [PATCH v2 4/6] drivers: soc: xilinx: Fix error message on SGI
> > registration failure
> > 
> > On Wed, Oct 04, 2023 at 02:41:14AM -0700, Jay Buddhabhatti wrote:
> > > Failure to register SGI for firmware event notification is non-fatal
> > > error when feature is not supported by other modules such as Xen and
> > > TF-A. Add _info level log message for such special case.
> > >
> > > Also add XST_PM_INVALID_VERSION error code and map it to -EOPNOSUPP
> > > Linux kernel error code. If feature is not supported or EEMI API
> > > version is mismatch, firmware can return XST_PM_INVALID_VERSION = 4 or
> > > XST_PM_NO_FEATURE = 19 error code.
> > >
> > > Co-developed-by: Tanmay Shah <tanmay.shah@xxxxxxx>
> > > Signed-off-by: Tanmay Shah <tanmay.shah@xxxxxxx>
> > > Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@xxxxxxx>
> > > ---
> > >  drivers/firmware/xilinx/zynqmp.c        | 4 +++-
> > >  drivers/soc/xilinx/xlnx_event_manager.c | 7 ++++++-
> > >  include/linux/firmware/xlnx-zynqmp.h    | 1 +
> > >  3 files changed, 10 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/firmware/xilinx/zynqmp.c
> > > b/drivers/firmware/xilinx/zynqmp.c
> > > index 00ea2508f692..de09d77cf1e4 100644
> > > --- a/drivers/firmware/xilinx/zynqmp.c
> > > +++ b/drivers/firmware/xilinx/zynqmp.c
> > > @@ -92,6 +92,8 @@ static int zynqmp_pm_ret_code(u32 ret_status)
> > >  		return 0;
> > >  	case XST_PM_NO_FEATURE:
> > >  		return -ENOTSUPP;
> > > +	case XST_PM_INVALID_VERSION:
> > > +		return -EOPNOTSUPP;
> > >  	case XST_PM_NO_ACCESS:
> > >  		return -EACCES;
> > >  	case XST_PM_ABORT_SUSPEND:
> > > @@ -379,7 +381,7 @@ int zynqmp_pm_register_sgi(u32 sgi_num, u32 reset)
> > >
> > >  	ret = zynqmp_pm_invoke_fn(TF_A_PM_REGISTER_SGI, sgi_num, reset,
> > 0, 0,
> > >  				  0, NULL);
> > > -	if (!ret)
> > > +	if (ret != -EOPNOTSUPP && !ret)
> > >  		return ret;
> > >
> > >  	/* try old implementation as fallback strategy if above fails */
> > > diff --git a/drivers/soc/xilinx/xlnx_event_manager.c
> > > b/drivers/soc/xilinx/xlnx_event_manager.c
> > > index 38cfc161a713..bfa5cf4a0cab 100644
> > > --- a/drivers/soc/xilinx/xlnx_event_manager.c
> > > +++ b/drivers/soc/xilinx/xlnx_event_manager.c
> > > @@ -653,7 +653,12 @@ static int xlnx_event_manager_probe(struct
> > > platform_device *pdev)
> > >
> > >  	ret = zynqmp_pm_register_sgi(sgi_num, 0);
> > >  	if (ret) {
> > > -		dev_err(&pdev->dev, "SGI %d Registration over TF-A failed with
> > %d\n", sgi_num, ret);
> > > +		if (ret == -EOPNOTSUPP)
> > > +			dev_info(&pdev->dev, "PM firmware event notification
> > not
> > > +supported\n");
> > 
> > Why is this "info"?  Why not error?
> [Jay] Because it is non-fatal error which will not cause kernel crash.

Neither do dev_err() messages :)

And something failed, this isn't just "here's some nice information", it
is "something went wrong" which should be a warning or error in my
opinion.

> > And what is userspace supposed to do with this information if it sees it?
> [Jay] This message indicates that SGI registration is not supported by other modules like TF-A or Xen. So user need to use TF-A with this support if they want to use event management driver.

So perhaps say that here too?  Otherwise how are they supposed to know
that?

thanks,

greg k-h