Re: [PATCH v2 1/2] mei: me: Add exported function to get the PCI ID list

[Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>]

On 9/12/2025 6:44 AM, Greg Kroah-Hartman wrote:
> On Thu, Sep 11, 2025 at 10:50:23AM -0700, Daniele Ceraolo Spurio wrote:
>> The intel GFX drivers (i915/xe) interface with the ME device for some of
>> their features (e.g. PXP, HDCP) via the component interface. Given that
>> the ME device can be hidden by BIOS/Coreboot, the GFX drivers need a
>> way to check if the device is available before attempting to bind the
>> component, otherwise they'll go ahead and initialize features that will
>> never work.
>> The simplest way to check if the device is available is to check the
>> available devices against the PCI ID list of the mei_me driver. To avoid
>> duplication, this patch adds an exported function that the GFX driver
>> can call to obtain the list. Locking around the checks, if required,
>> is left to the caller.
>>
>> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>> Cc: Alexander Usyskin <alexander.usyskin@intel.com>
>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> ---
>>   drivers/misc/mei/pci-me.c | 22 ++++++++++++++++++++++
>>   include/linux/mei_me.h    | 20 ++++++++++++++++++++
>>   2 files changed, 42 insertions(+)
>>   create mode 100644 include/linux/mei_me.h
>>
>> diff --git a/drivers/misc/mei/pci-me.c b/drivers/misc/mei/pci-me.c
>> index 3f9c60b579ae..147e79b4ae1f 100644
>> --- a/drivers/misc/mei/pci-me.c
>> +++ b/drivers/misc/mei/pci-me.c
>> @@ -18,6 +18,7 @@
>>   #include <linux/pm_runtime.h>
>>   
>>   #include <linux/mei.h>
>> +#include <linux/mei_me.h>
>>   
>>   #include "mei_dev.h"
>>   #include "client.h"
>> @@ -133,6 +134,27 @@ static const struct pci_device_id mei_me_pci_tbl[] = {
>>   
>>   MODULE_DEVICE_TABLE(pci, mei_me_pci_tbl);
>>   
>> +/**
>> + * mei_me_get_device_id_table - get the list of ME pci device IDs
>> + *
>> + * Other drivers (e.g., i915, xe) interface with the ME device for some of their
>> + * features (e.g., PXP, HDCP). However, the ME device can be unplugged via the
>> + * pci subsystem or hidden by BIOS/coreboot, so those drivers might want to
>> + * check if the device is available before initializing those features. This
>> + * function offers a way for those drivers to get the list of ME device IDs,
>> + * so they can check if one of them is available before attempting to
>> + * interface with it. Locking around the availability check, if required,
>> + * is left to the caller.
>> + *
>> + * Return: An array of struct pci_device_id entries containing the IDs of
>> + * the ME devices.
>> + */
>> +const struct pci_device_id *mei_me_get_device_id_table(void)
>> +{
>> +	return mei_me_pci_tbl;
>> +}
>> +EXPORT_SYMBOL_GPL(mei_me_get_device_id_table);
> Why not just do:
>
> 	EXPORT_SYMBOL_GPL(mei_me_pci_tbl);
>
> instead?
>
> Much simpler :)

Good point! :P
I'll update.

Thanks,
Daniele

>
> thanks,
>
> greg k-h