Re: [PATCH -next] smsc911x: Fix crash seen if neither ACPI nor OF is configured or used

[Guenter Roeck]

Hi Tony,

On 08/26/2015 10:04 AM, Tony Lindgren wrote:
> Hi,
>
> * Guenter Roeck <linux@xxxxxxxxxxxx> [150817 13:48]:
> > Commit 0b50dc4fc971 ("Convert smsc911x to use ACPI as well as DT") makes
> > the call to smsc911x_probe_config() unconditional, and no longer fails if
> > there is no device node. device_get_phy_mode() is called unconditionally,
> > and if there is no phy node configured returns an error code. This error
> > code is assigned to phy_interface, and interpreted elsewhere in the code
> > as valid phy mode. This in turn causes qemu to crash when running a
> > variant of realview_pb_defconfig.
> >
> > 	qemu: hardware error: lan9118_read: Bad reg 0x86
> >
> > Fixes: 0b50dc4fc971 ("Convert smsc911x to use ACPI as well as DT")
> > Cc: Jeremy Linton <jeremy.linton@xxxxxxx>
> > Cc Graeme Gregory <graeme.gregory@xxxxxxxxxx>
> > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > ---
> >   drivers/net/ethernet/smsc/smsc911x.c | 7 ++++++-
> >   1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
> > index 0f21aa3bb537..34f97684506b 100644
> > --- a/drivers/net/ethernet/smsc/smsc911x.c
> > +++ b/drivers/net/ethernet/smsc/smsc911x.c
> > @@ -2367,12 +2367,17 @@ static const struct smsc911x_ops shifted_smsc911x_ops = {
> >   static int smsc911x_probe_config(struct smsc911x_platform_config *config,
> >   				 struct device *dev)
> >   {
> > +	int phy_interface;
> >   	u32 width = 0;
> >
> >   	if (!dev)
> >   		return -ENODEV;
> >
> > -	config->phy_interface = device_get_phy_mode(dev);
> > +	phy_interface = device_get_phy_mode(dev);
> > +	if (phy_interface < 0)
> > +		return phy_interface;
> > +
> > +	config->phy_interface = phy_interface;
> >
> >   	device_get_mac_address(dev, config->mac, ETH_ALEN);
>
> Looks like this change makes at least omap boards using smsc911x
> fail with -22 for me in Linux next.

What do you see if you revert my patch ? It should assign -22, or its
unsigned representation, to phy_interface, which isn't such a good idea
either.

> Do any of the the device tree configured smsc911x devices actually
> have a phy configured?
Good question, and beats me. Looking into the original code,
it didn't check for an error return from of_get_phy_mode() either,
and thus _would_ dutifully assign the error code to phy_interface.
Wonder how was this supposed to work to start with.

I'll do some debugging and try to find out what exactly is going on.

Guenter

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