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

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Message-ID: <c2090596-3aab-fc1a-4fdf-f28f688cc666@redhat.com>
Date:   Wed, 1 Mar 2023 16:49:54 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Limonciello, Mario" <Mario.Limonciello@....com>,
        "S-k, Shyam-sundar" <Shyam-sundar.S-k@....com>
Cc:     Mark Gross <markgross@...nel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] platform/x86/amd: pmc: Add a helper for checking
 minimum SMU version

Hi,

On 3/1/23 16:31, Limonciello, Mario wrote:
> [Public]
> 
> 
> 
>> -----Original Message-----
>> From: Hans de Goede <hdegoede@...hat.com>
>> Sent: Wednesday, March 1, 2023 09:28
>> To: Limonciello, Mario <Mario.Limonciello@....com>; S-k, Shyam-sundar
>> <Shyam-sundar.S-k@....com>
>> Cc: Mark Gross <markgross@...nel.org>; platform-driver-
>> x86@...r.kernel.org; linux-kernel@...r.kernel.org
>> 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@....com>
>>> ---
>>>  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?
> 
>>
>> 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.

I'm fine with keeping the order as is, I'm also fine with swapping it :)

Regards,

Hans