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Date: Thu, 9 Nov 2017 14:33:13 -0800 From: sathyanarayanan kuppuswamy <sathyanarayanan.kuppuswamy@...ux.intel.com> To: Mario.Limonciello@...l.com, dvhart@...radead.org, andy.shevchenko@...il.com Cc: linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org, pali.rohar@...il.com Subject: Re: [PATCH v2 2/2] platform/x86: dell-*wmi*: Relay failed initial probe to dependent drivers Hi, On 11/09/2017 11:00 AM, Mario.Limonciello@...l.com wrote: > >> -----Original Message----- >> From: platform-driver-x86-owner@...r.kernel.org [mailto:platform-driver-x86- >> owner@...r.kernel.org] On Behalf Of sathyanarayanan kuppuswamy >> Sent: Thursday, November 9, 2017 12:51 PM >> To: Limonciello, Mario <Mario_Limonciello@...l.com>; dvhart@...radead.org; >> Andy Shevchenko <andy.shevchenko@...il.com> >> Cc: LKML <linux-kernel@...r.kernel.org>; platform-driver-x86@...r.kernel.org; >> pali.rohar@...il.com >> 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. Got it. Thanks for the clarification. > > 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@...l.com> >>> --- >>> 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 -- Sathyanarayanan Kuppuswamy Linux kernel developer
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