linux-kernel - Re: [PATCH 4/7] platform/x86: hp-bioscfg: Use wmi_instance

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Message-ID: <b7375996-cf85-d1c3-fd29-585bb22a99c1@linux.intel.com>
Date: Tue, 4 Feb 2025 16:27:54 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Armin Wolf <W_Armin@....de>
cc: james@...iv.tech, markpearson@...ovo.com, jorge.lopez2@...com, 
    jdelvare@...e.com, linux@...ck-us.net, linux-hwmon@...r.kernel.org, 
    LKML <linux-kernel@...r.kernel.org>, Hans de Goede <hdegoede@...hat.com>, 
    platform-driver-x86@...r.kernel.org, corbet@....net, 
    linux-doc@...r.kernel.org
Subject: Re: [PATCH 4/7] platform/x86: hp-bioscfg: Use wmi_instance_count()

On Tue, 4 Feb 2025, Armin Wolf wrote:

> Am 04.02.25 um 11:37 schrieb Ilpo Järvinen:
> 
> > On Mon, 3 Feb 2025, Armin Wolf wrote:
> > 
> > > The WMI core already knows the instance count of a WMI guid.
> > > Use this information instead of querying all possible instances
> > > which is slow and might be unreliable.
> > > 
> > > Signed-off-by: Armin Wolf <W_Armin@....de>
> > > ---
> > >   drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 13 +++++--------
> > >   1 file changed, 5 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> > > b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> > > index 0b277b7e37dd..63c78b4d8258 100644
> > > --- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> > > +++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> > > @@ -388,16 +388,13 @@ union acpi_object *hp_get_wmiobj_pointer(int
> > > instance_id, const char *guid_strin
> > >    */
> > >   int hp_get_instance_count(const char *guid_string)
> > >   {
> > > -	union acpi_object *wmi_obj = NULL;
> > > -	int i = 0;
> > > +	int ret;
> > > 
> > > -	do {
> > > -		kfree(wmi_obj);
> > > -		wmi_obj = hp_get_wmiobj_pointer(i, guid_string);
> > > -		i++;
> > > -	} while (wmi_obj);
> > > +	ret = wmi_instance_count(guid_string);
> > > +	if (ret < 0)
> > > +		return 0;
> > > 
> > > -	return i - 1;
> > > +	return ret;
> > >   }
> > Hi Armin,
> > 
> > While it is the existing way of doing things, I don't like how the error
> > is not properly passed on here. And if the error handling is pushed
> > upwards to the calling sites, then this entire function becomes useless
> > and wmi_instance_count() could be used directly in the callers.
>
> The thing is that for the hp-bioscfg driver, a missing WMI GUID is not an
> error.
> In this case 0 instances are available.
> 
> I would keep this function for now.

Okay, fine.

-- 
 i.