> -----Original Message----- > From: platform-driver-x86-owner@xxxxxxxxxxxxxxx [mailto:platform-driver-x86- > owner@xxxxxxxxxxxxxxx] On Behalf Of sathyanarayanan kuppuswamy > Sent: Thursday, November 9, 2017 12:51 PM > To: Limonciello, Mario <Mario_Limonciello@xxxxxxxx>; dvhart@xxxxxxxxxxxxx; > Andy Shevchenko <andy.shevchenko@xxxxxxxxx> > Cc: LKML <linux-kernel@xxxxxxxxxxxxxxx>; platform-driver-x86@xxxxxxxxxxxxxxx; > pali.rohar@xxxxxxxxx > Subject: Re: [PATCH v2 2/2] platform/x86: dell-*wmi*: Relay failed initial probe to > dependent drivers > > Hi, > > > On 11/09/2017 09:49 AM, Mario Limonciello wrote: > > dell-wmi and dell-smbios-wmi are dependent upon dell-wmi-descriptor > > finishing probe successfully to probe themselves. > if they are dependent, then why not control the device creation of > dell-wmi and dell-smbios-wmi drivers in del-wmi-descriptor probe ? The dependency is just in a function call that dell-wmi-descriptor provides information to the other drivers. Each of these is a driver that binds to a GUID on the WMI bus. They can each be built/configured independently of one another and also independently bound or unbound to a GUID on the WMI bus. Since these are bus drivers, the WMI bus will control creation of devices when probe routines are run. > > > 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: > > -ENODEV: Descriptor GUID missing from WMI bus > > -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. > > > > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxxx> > > --- > > drivers/platform/x86/dell-smbios-wmi.c | 5 +++-- > > drivers/platform/x86/dell-wmi-descriptor.c | 16 ++++++++++++++++ > > drivers/platform/x86/dell-wmi-descriptor.h | 8 +++++++- > > drivers/platform/x86/dell-wmi.c | 6 ++++-- > > 4 files changed, 30 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/platform/x86/dell-smbios-wmi.c b/drivers/platform/x86/dell- > smbios-wmi.c > > index 35c13815b24c..ca556803c8c9 100644 > > --- a/drivers/platform/x86/dell-smbios-wmi.c > > +++ b/drivers/platform/x86/dell-smbios-wmi.c > > @@ -148,8 +148,9 @@ static int dell_smbios_wmi_probe(struct wmi_device > *wdev) > > int count; > > int ret; > > > > - 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); > > diff --git a/drivers/platform/x86/dell-wmi-descriptor.c > b/drivers/platform/x86/dell-wmi-descriptor.c > > index 28ef5f37cfbf..4dfef1f53481 100644 > > --- a/drivers/platform/x86/dell-wmi-descriptor.c > > +++ b/drivers/platform/x86/dell-wmi-descriptor.c > > @@ -21,14 +21,26 @@ > > #include <linux/wmi.h> > > #include "dell-wmi-descriptor.h" > > > > +#define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012- > B622A1EF5492" > > + > > struct descriptor_priv { > > struct list_head list; > > 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) > > +{ > > + if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID)) > > + return -ENODEV; > > + > > + 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 +103,7 @@ 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 +115,7 @@ 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 +125,10 @@ 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..1e8cb96ffd78 100644 > > --- a/drivers/platform/x86/dell-wmi-descriptor.h > > +++ b/drivers/platform/x86/dell-wmi-descriptor.h > > @@ -13,7 +13,13 @@ > > > > #include <linux/wmi.h> > > > > -#define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012- > B622A1EF5492" > > +/* possible return values: > > + * -ENODEV: Descriptor GUID missing from WMI bus > > + * -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..39d2f4518483 100644 > > --- a/drivers/platform/x86/dell-wmi.c > > +++ b/drivers/platform/x86/dell-wmi.c > > @@ -655,9 +655,11 @@ 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; > > + ret = dell_wmi_get_descriptor_valid(); > > + if (ret) > > + return ret; > > > > priv = devm_kzalloc( > > &wdev->dev, sizeof(struct dell_wmi_priv), GFP_KERNEL); > > -- > Sathyanarayanan Kuppuswamy > Linux kernel developer
