> -----Original Message----- > From: Pali Rohár [mailto:pali.rohar@xxxxxxxxx] > Sent: Thursday, November 9, 2017 10:03 AM > To: Limonciello, Mario <Mario_Limonciello@xxxxxxxx> > Cc: dvhart@xxxxxxxxxxxxx; Andy Shevchenko <andy.shevchenko@xxxxxxxxx>; > LKML <linux-kernel@xxxxxxxxxxxxxxx>; platform-driver-x86@xxxxxxxxxxxxxxx > Subject: Re: [PATCH 2/2] platform/x86: dell-*wmi*: Relay failed initial probe to > dependent drivers > > On Friday 03 November 2017 11:27:22 Mario Limonciello wrote: > > dell-wmi and dell-smbios-wmi are dependent upon dell-wmi-descriptor > > finishing probe successfully to probe themselves. > > > > Currently if dell-wmi-descriptor fails probing in a non-recoverable way > > (such as invalid header) dell-wmi and dell-smbios-wmi will continue to > > try to redo probing due to deferred probing. > > > > To solve this have the dependent drivers query the dell-wmi-descriptor > > driver whether the descriptor has been determined valid. The possible > > results are: > > -EPROBE_DEFER: Descriptor not yet probed, dependent driver should wait > > and use deferred probing > > < 0: Descriptor probed, invalid. Dependent driver should return an > > error. > > 0: Successful descriptor probe, dependent driver can continue > > > > Successful descriptor probe still doesn't mean that the descriptor driver > > is necessarily bound at the time of initialization of dependent driver. > > Userspace can unbind the driver, so all methods used from driver > > should still be verified to return success values otherwise deferred > > probing be used. > > Darren, Andy, any comments on this patch? > > I think now it should work also those corner, but legit cases. > > > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxxx> > > --- > > drivers/platform/x86/dell-smbios-wmi.c | 4 ++++ > > drivers/platform/x86/dell-wmi-descriptor.c | 11 +++++++++++ > > drivers/platform/x86/dell-wmi-descriptor.h | 7 +++++++ > > drivers/platform/x86/dell-wmi.c | 5 +++++ > > 4 files changed, 27 insertions(+) > > > > diff --git a/drivers/platform/x86/dell-smbios-wmi.c b/drivers/platform/x86/dell- > smbios-wmi.c > > index 35c13815b24c..3fa53fa174b2 100644 > > --- a/drivers/platform/x86/dell-smbios-wmi.c > > +++ b/drivers/platform/x86/dell-smbios-wmi.c > > @@ -151,6 +151,10 @@ static int dell_smbios_wmi_probe(struct wmi_device > *wdev) > > if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID)) > > return -ENODEV; > > > > + ret = dell_wmi_get_descriptor_valid(); > > + if (ret) > > + return ret; > > + > > priv = devm_kzalloc(&wdev->dev, sizeof(struct wmi_smbios_priv), > > GFP_KERNEL); > > if (!priv) > > diff --git a/drivers/platform/x86/dell-wmi-descriptor.c > b/drivers/platform/x86/dell-wmi-descriptor.c > > index 28ef5f37cfbf..e7f4c3a7bfc4 100644 > > --- a/drivers/platform/x86/dell-wmi-descriptor.c > > +++ b/drivers/platform/x86/dell-wmi-descriptor.c > > @@ -26,9 +26,16 @@ struct descriptor_priv { > > u32 interface_version; > > u32 size; > > }; > > +static int descriptor_valid = -EPROBE_DEFER; > > static LIST_HEAD(wmi_list); > > static DEFINE_MUTEX(list_mutex); > > > > +int dell_wmi_get_descriptor_valid(void) > > +{ > > + return descriptor_valid; > > +} > > +EXPORT_SYMBOL_GPL(dell_wmi_get_descriptor_valid); > > + > > bool dell_wmi_get_interface_version(u32 *version) > > { > > struct descriptor_priv *priv; > > @@ -91,6 +98,7 @@ static int dell_wmi_descriptor_probe(struct wmi_device > *wdev) > > if (obj->type != ACPI_TYPE_BUFFER) { > > dev_err(&wdev->dev, "Dell descriptor has wrong type\n"); > > ret = -EINVAL; > > + descriptor_valid = ret; > > goto out; > > } > > > > @@ -102,6 +110,7 @@ static int dell_wmi_descriptor_probe(struct wmi_device > *wdev) > > "Dell descriptor buffer has unexpected length (%d)\n", > > obj->buffer.length); > > ret = -EINVAL; > > + descriptor_valid = ret; > > goto out; > > } > > > > @@ -111,8 +120,10 @@ static int dell_wmi_descriptor_probe(struct wmi_device > *wdev) > > dev_err(&wdev->dev, "Dell descriptor buffer has invalid signature > (%8ph)\n", > > buffer); > > ret = -EINVAL; > > + descriptor_valid = ret; > > goto out; > > } > > + descriptor_valid = 0; > > > > if (buffer[2] != 0 && buffer[2] != 1) > > dev_warn(&wdev->dev, "Dell descriptor buffer has unknown > version (%lu)\n", > > diff --git a/drivers/platform/x86/dell-wmi-descriptor.h > b/drivers/platform/x86/dell-wmi-descriptor.h > > index 5f7b69c2c83a..776cddd5e135 100644 > > --- a/drivers/platform/x86/dell-wmi-descriptor.h > > +++ b/drivers/platform/x86/dell-wmi-descriptor.h > > @@ -15,6 +15,13 @@ > > > > #define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012- > B622A1EF5492" > > > > +/* possible return values: > > + * -EPROBE_DEFER: probing for dell-wmi-descriptor not yet run > > + * 0: valid descriptor, successfully probed > > + * < 0: invalid descriptor, don't probe dependent devices > > + */ > > +int dell_wmi_get_descriptor_valid(void); > > + > > bool dell_wmi_get_interface_version(u32 *version); > > bool dell_wmi_get_size(u32 *size); > > > > diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c > > index 54321080a30d..bb7c1e681792 100644 > > --- a/drivers/platform/x86/dell-wmi.c > > +++ b/drivers/platform/x86/dell-wmi.c > > @@ -655,10 +655,15 @@ static int dell_wmi_events_set_enabled(bool enable) > > static int dell_wmi_probe(struct wmi_device *wdev) > > { > > struct dell_wmi_priv *priv; > > + int ret; > > > > if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID)) > > return -ENODEV; > > Just one suggestion, is above check still needed in dell-wmi.c code? > I think that now it should be job of dell_wmi_get_descriptor_valid() > function to fully validate if dell wmi descriptor driver is able to > provide all needed information for dell-wmi driver. > Yes, I believe it's still needed because if the GUID isn't on the bus the probe routine for dell-wmi-descriptor won't run and dell_wmi_get_descriptor_valid() will continually return -EPROBE_DEFER. That's the exact problem this patch exists for (preventing infinite deferred probing). Perhaps a "cleaner" solution is to have the init routine of dell-wmi-descriptor do this wmi_has_guid check and set the descriptor_valid variable to -ENODEV so that "dependent" drivers don't need to. > > + ret = dell_wmi_get_descriptor_valid(); > > + if (ret) > > + return ret; > > + > > priv = devm_kzalloc( > > &wdev->dev, sizeof(struct dell_wmi_priv), GFP_KERNEL); > > if (!priv) > > -- > Pali Rohár > pali.rohar@xxxxxxxxx
