linux-kernel - Re: [PATCH] HID: amd_sfh: Ignore uninitialized device

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Date:   Wed, 29 Jun 2022 00:11:46 +0900
From:   Akihiko Odaki <akihiko.odaki@...il.com>
To:     "Limonciello, Mario" <mario.limonciello@....com>
Cc:     Basavaraj Natikar <basavaraj.natikar@....com>,
        Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] HID: amd_sfh: Ignore uninitialized device

On 2022/06/28 23:42, Limonciello, Mario wrote:
> On 6/26/2022 03:13, Akihiko Odaki wrote:
>> Lenovo ThinkPad C13 Yoga has AMD Sensor Fusion Hub, but it is not used
>> because Chrome OS EC Sensor Hub is used instead. The system therefore
>> never loads the firmware for MP2 and MP2 does not work. It results in
>> AMD_P2C_MSG3 register to have -1 as its value.
>>
>> Without this change, the driver interprets the value as it supports all
>> sensor types and exposes them, which confuses a userspace program,
>> iio-sensor-proxy, and makes it to use the non-functioning sensors
>> instead of functioning sensors exposed via Chrome OS EC Sensor Hub.
>>
>> Check the version bits included in AMD_P2C_MSG3 register and ignore the
>> device if all of the bits are set.
>>
> 
> Have you already confirmed this failure happens in 5.19-rc1 or later as 
> well?  I would think that b5d7f43e97dabfa04a4be5ff027ce7da119332be 
> should have fixed it.

Yes. I confirmed it with 78ca55889a549a9a194c6ec666836329b774ab6d.

b5d7f43e97dabfa04a4be5ff027ce7da119332be deals with the case where it 
advertises v2 but it doesn't in my case.

Regards,
Akihiko Odaki

> 
>> Signed-off-by: Akihiko Odaki <akihiko.odaki@...il.com>
>> ---
>>   drivers/hid/amd-sfh-hid/amd_sfh_pcie.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c 
>> b/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
>> index dadc491bbf6b..4137e5da77ad 100644
>> --- a/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
>> +++ b/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
>> @@ -271,6 +271,8 @@ static void mp2_select_ops(struct amd_mp2_dev 
>> *privdata)
>>       case V2_STATUS:
>>           privdata->mp2_ops = &amd_sfh_ops_v2;
>>           break;
>> +    case 15:
>> +        break;
>>       default:
>>           privdata->mp2_ops = &amd_sfh_ops;
>>           break;
>> @@ -317,6 +319,8 @@ static int amd_mp2_pci_probe(struct pci_dev *pdev, 
>> const struct pci_device_id *i
>>           return -ENOMEM;
>>       mp2_select_ops(privdata);
>> +    if (!privdata->mp2_ops)
>> +        return -ENODEV;
>>       rc = amd_sfh_irq_init(privdata);
>>       if (rc) {
>