Re: [PATCH 1/2] platform/x86/amd: pmc: Add a helper for checking minimum SMU version

[Shyam Sundar S K]

On 3/2/2023 8:12 AM, Mario Limonciello wrote:
> On 3/1/23 20:39, Shyam Sundar S K wrote:
>> Hi Mario,
>>
>> On 3/1/2023 9:01 PM, Limonciello, Mario wrote:
>>> [Public]
>>>
>>>
>>>
>>>> -----Original Message-----
>>>> From: Hans de Goede <hdegoede@xxxxxxxxxx>
>>>> Sent: Wednesday, March 1, 2023 09:28
>>>> To: Limonciello, Mario <Mario.Limonciello@xxxxxxx>; S-k, Shyam-sundar
>>>> <Shyam-sundar.S-k@xxxxxxx>
>>>> Cc: Mark Gross <markgross@xxxxxxxxxx>; platform-driver-
>>>> x86@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
>>>> Subject: Re: [PATCH 1/2] platform/x86/amd: pmc: Add a helper for
>>>> checking
>>>> minimum SMU version
>>>>
>>>> Hi,
>>>>
>>>> On 3/1/23 16:08, Mario Limonciello wrote:
>>>>> In a few locations there is some boilerplate code for checking
>>>>> minimum SMU version.  Switch this to a helper for this check.
>>>>>
>>>>> No intended functional changes.
>>>>>
>>>>> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
>>>>> ---
>>>>>   drivers/platform/x86/amd/pmc.c | 49
>>>>> +++++++++++++++++-----------------
>>>>>   1 file changed, 24 insertions(+), 25 deletions(-)
>>>>>
>>>>> diff --git a/drivers/platform/x86/amd/pmc.c
>>>> b/drivers/platform/x86/amd/pmc.c
>>>>> index 2edaae04a691..c42fa47381c3 100644
>>>>> --- a/drivers/platform/x86/amd/pmc.c
>>>>> +++ b/drivers/platform/x86/amd/pmc.c
>>>>> @@ -418,6 +418,22 @@ static int amd_pmc_get_smu_version(struct
>>>> amd_pmc_dev *dev)
>>>>>       return 0;
>>>>>   }
>>>>>
>>>>> +static bool amd_pmc_verify_min_version(struct amd_pmc_dev *pdev,
>>>> int major, int minor)
>>>>> +{
>>>>> +    if (!pdev->major) {
>>>>> +        int rc = amd_pmc_get_smu_version(pdev);
>>>>> +
>>>>> +        if (rc) {
>>>>> +            dev_warn(pdev->dev, "failed to read SMU version:
>>>> %d\n", rc);
>>>>> +            return false;
>>>>> +        }
>>>>> +    }
>>>>> +    if (pdev->major > major)
>>>>> +        return true;
>>>>> +
>>>>> +    return pdev->major == major && pdev->minor >= minor;
>>>>> +}
>>>>> +
>>>>>   static ssize_t smu_fw_version_show(struct device *d, struct
>>>> device_attribute *attr,
>>>>>                      char *buf)
>>>>>   {
>>>>> @@ -526,14 +542,7 @@ static int amd_pmc_idlemask_show(struct seq_file
>>>> *s, void *unused)
>>>>>       struct amd_pmc_dev *dev = s->private;
>>>>>       int rc;
>>>>>
>>>>> -    /* we haven't yet read SMU version */
>>>>> -    if (!dev->major) {
>>>>> -        rc = amd_pmc_get_smu_version(dev);
>>>>> -        if (rc)
>>>>> -            return rc;
>>>>> -    }
>>>>> -
>>>>> -    if (dev->major > 56 || (dev->major >= 55 && dev->minor >= 37)) {
>>>>
>>>> The 2 major checks here originally were not in sync, so for major == 55
>>>> *and* major == 56 it would only succeed if minor >= 37.
>>>>
>>>> Where as after this patch for major == 56 it will now always succeed.
>>>>
>>>> This feels like a bug in the original code, but might have been
>>>> intentional ? Please verify this.
>>>
>>> @S-k, Shyam-sundar as the original author of that, can you please
>>> confirm?
>>
>> I cannot completely recall :-) It was something like if the major
>> version is greater than 56, there is no need to check the other part of
>> the "OR".
>>
>> which is kind of similar to what you are now doing in
>> amd_pmc_verify_min_version().
> 
> OK yeah, then I'll split this correction of the logic off to that in a
> separate patch to make this one "really no intended functional changes".
> 
>>
>> Like we discussed off-list, we should have this boilerplate in place, so
>> that the future checks would not be duplicated.
> 
> Something else I noticed that we probably need to consider is that there
> is no examination for the "program" version which may be important.
> 
> We don't have any version checks for YC, but if we did for example YC A0
> and YC B0 use program "0" or program "4" respectively so version checks
> could fall over.

Checking for "program" version may not be required as A0/B0 are never
meant for production and IMO its a logical overhead.

Do you have a specific case, were you felt the real usage of "program"
version?

> 
> I'll add something like this in for v2 of the patch as well.
> 
>>
>> Thanks,
>> Shyam
>>
>>>
>>>>
>>>> After verifying please post a v2 updating the commit message to
>>>> point out this functional change.
>>>>
>>>
>>> Sure, thanks.
>>>
>>>>> +    if (amd_pmc_verify_min_version(dev, 55, 37)) {
>>>>>           rc = amd_pmc_idlemask_read(dev, NULL, s);
>>>>>           if (rc)
>>>>>               return rc;
>>>>> @@ -686,15 +695,8 @@ static int amd_pmc_get_os_hint(struct
>>>> amd_pmc_dev *dev)
>>>>>   static int amd_pmc_czn_wa_irq1(struct amd_pmc_dev *pdev)
>>>>>   {
>>>>>       struct device *d;
>>>>> -    int rc;
>>>>>
>>>>> -    if (!pdev->major) {
>>>>> -        rc = amd_pmc_get_smu_version(pdev);
>>>>> -        if (rc)
>>>>> -            return rc;
>>>>> -    }
>>>>> -
>>>>> -    if (pdev->major > 64 || (pdev->major == 64 && pdev->minor > 65))
>>>>> +    if (amd_pmc_verify_min_version(pdev, 64, 66))
>>>>>           return 0;
>>>>>
>>>>>       d = bus_find_device_by_name(&serio_bus, NULL, "serio0");
>>>>> @@ -718,14 +720,10 @@ static int amd_pmc_verify_czn_rtc(struct
>>>> amd_pmc_dev *pdev, u32 *arg)
>>>>>       struct rtc_time tm;
>>>>>       int rc;
>>>>>
>>>>> -    /* we haven't yet read SMU version */
>>>>> -    if (!pdev->major) {
>>>>> -        rc = amd_pmc_get_smu_version(pdev);
>>>>> -        if (rc)
>>>>> -            return rc;
>>>>> -    }
>>>>> +    if (disable_workarounds)
>>>>> +        return 0;
>>>>>
>>>>> -    if (pdev->major < 64 || (pdev->major == 64 && pdev->minor < 53))
>>>>> +    if (!amd_pmc_verify_min_version(pdev, 64, 53))
>>>>>           return 0;
>>>>>
>>>>>       rtc_device = rtc_class_open("rtc0");
>>>>> @@ -772,13 +770,14 @@ static void amd_pmc_s2idle_prepare(void)
>>>>>       /* Reset and Start SMU logging - to monitor the s0i3 stats */
>>>>>       amd_pmc_setup_smu_logging(pdev);
>>>>>
>>>>> -    /* Activate CZN specific platform bug workarounds */
>>>>> -    if (pdev->cpu_id == AMD_CPU_ID_CZN && !disable_workarounds) {
>>>>> +    switch (pdev->cpu_id) {
>>>>> +    case AMD_CPU_ID_CZN:
>>>>>           rc = amd_pmc_verify_czn_rtc(pdev, &arg);
>>>>>           if (rc) {
>>>>>               dev_err(pdev->dev, "failed to set RTC: %d\n", rc);
>>>>>               return;
>>>>>           }
>>>>> +        break;
>>>>>       }
>>>>>
>>>>>       msg = amd_pmc_get_os_hint(pdev);
>>>>
>>>>
>>>> Patch 2/2 looks good to me.
>>>>
>>>> Should I queue v2 (once posted) up as a fix for 6.3-rc#  ?
>>>
>>> Yes please.  If it makes it easier I can re-order the series so that
>>> we add a check in 1/2 and switch to the helper as 2/2.
>>>
>>> This might make it easier to take the LTS kernel too for stable,
>>> but I don't feel strongly.
>>>
>>>>
>>>> Regards,
>>>>
>>>> Hans
>