Re: [PATCH v2] platform/x86:intel/pmc: Ignore all LTRs during suspend

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 9/11/24 2:16 PM, Hans de Goede wrote:
> Hi,
> 
> On 9/6/24 8:40 PM, Xi Pardee wrote:
>> From: Xi Pardee <xi.pardee@intel.com>
>>
>> Add support to ignore all LTRs before suspend and restore the previous
>> LTR values after suspend. This feature could be turned off with module
>> parameter ltr_ignore_all_suspend.
>>
>> LTR value is a mechanism for a device to indicate tolerance to access
>> the corresponding resource. When system suspends, the resource is not
>> available and therefore the LTR value could be ignored. Ignoring all
>> LTR values prevents problematic device from blocking the system to get
>> to the deepest package state during suspend.
>>
>> Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>> Signed-off-by: Xi Pardee <xi.pardee@intel.com>
> 
> Thanks, patch looks good to me:
> 
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Oops, wrong auto-reply, what I meant is:

Thank you for your patch, I've applied this patch to my review-hans 
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

Regards,

Hans




>> v2:
>> - Add more details to commit message
>> - Fix format: ltr->LTR, S0IX->S0ix, space between name and email
>>
>> ---
>>  drivers/platform/x86/intel/pmc/core.c | 53 +++++++++++++++++++++++++++
>>  drivers/platform/x86/intel/pmc/core.h |  2 +
>>  2 files changed, 55 insertions(+)
>>
>> diff --git a/drivers/platform/x86/intel/pmc/core.c b/drivers/platform/x86/intel/pmc/core.c
>> index 01ae71c6df59..0ec703af16a4 100644
>> --- a/drivers/platform/x86/intel/pmc/core.c
>> +++ b/drivers/platform/x86/intel/pmc/core.c
>> @@ -714,6 +714,49 @@ static int pmc_core_s0ix_blocker_show(struct seq_file *s, void *unused)
>>  }
>>  DEFINE_SHOW_ATTRIBUTE(pmc_core_s0ix_blocker);
>>  
>> +static void pmc_core_ltr_ignore_all(struct pmc_dev *pmcdev)
>> +{
>> +	unsigned int i;
>> +
>> +	for (i = 0; i < ARRAY_SIZE(pmcdev->pmcs); i++) {
>> +		struct pmc *pmc;
>> +		u32 ltr_ign;
>> +
>> +		pmc = pmcdev->pmcs[i];
>> +		if (!pmc)
>> +			continue;
>> +
>> +		guard(mutex)(&pmcdev->lock);
>> +		pmc->ltr_ign = pmc_core_reg_read(pmc, pmc->map->ltr_ignore_offset);
>> +
>> +		/* ltr_ignore_max is the max index value for LTR ignore register */
>> +		ltr_ign = pmc->ltr_ign | GENMASK(pmc->map->ltr_ignore_max, 0);
>> +		pmc_core_reg_write(pmc, pmc->map->ltr_ignore_offset, ltr_ign);
>> +	}
>> +
>> +	/*
>> +	 * Ignoring ME during suspend is blocking platforms with ADL PCH to get to
>> +	 * deeper S0ix substate.
>> +	 */
>> +	pmc_core_send_ltr_ignore(pmcdev, 6, 0);
>> +}
>> +
>> +static void pmc_core_ltr_restore_all(struct pmc_dev *pmcdev)
>> +{
>> +	unsigned int i;
>> +
>> +	for (i = 0; i < ARRAY_SIZE(pmcdev->pmcs); i++) {
>> +		struct pmc *pmc;
>> +
>> +		pmc = pmcdev->pmcs[i];
>> +		if (!pmc)
>> +			continue;
>> +
>> +		guard(mutex)(&pmcdev->lock);
>> +		pmc_core_reg_write(pmc, pmc->map->ltr_ignore_offset, pmc->ltr_ign);
>> +	}
>> +}
>> +
>>  static inline u64 adjust_lpm_residency(struct pmc *pmc, u32 offset,
>>  				       const int lpm_adj_x2)
>>  {
>> @@ -1479,6 +1522,10 @@ static bool warn_on_s0ix_failures;
>>  module_param(warn_on_s0ix_failures, bool, 0644);
>>  MODULE_PARM_DESC(warn_on_s0ix_failures, "Check and warn for S0ix failures");
>>  
>> +static bool ltr_ignore_all_suspend = true;
>> +module_param(ltr_ignore_all_suspend, bool, 0644);
>> +MODULE_PARM_DESC(ltr_ignore_all_suspend, "Ignore all LTRs during suspend");
>> +
>>  static __maybe_unused int pmc_core_suspend(struct device *dev)
>>  {
>>  	struct pmc_dev *pmcdev = dev_get_drvdata(dev);
>> @@ -1488,6 +1535,9 @@ static __maybe_unused int pmc_core_suspend(struct device *dev)
>>  	if (pmcdev->suspend)
>>  		pmcdev->suspend(pmcdev);
>>  
>> +	if (ltr_ignore_all_suspend)
>> +		pmc_core_ltr_ignore_all(pmcdev);
>> +
>>  	/* Check if the syspend will actually use S0ix */
>>  	if (pm_suspend_via_firmware())
>>  		return 0;
>> @@ -1594,6 +1644,9 @@ static __maybe_unused int pmc_core_resume(struct device *dev)
>>  {
>>  	struct pmc_dev *pmcdev = dev_get_drvdata(dev);
>>  
>> +	if (ltr_ignore_all_suspend)
>> +		pmc_core_ltr_restore_all(pmcdev);
>> +
>>  	if (pmcdev->resume)
>>  		return pmcdev->resume(pmcdev);
>>  
>> diff --git a/drivers/platform/x86/intel/pmc/core.h b/drivers/platform/x86/intel/pmc/core.h
>> index ea04de7eb9e8..e862ea88b816 100644
>> --- a/drivers/platform/x86/intel/pmc/core.h
>> +++ b/drivers/platform/x86/intel/pmc/core.h
>> @@ -372,6 +372,7 @@ struct pmc_info {
>>   * @map:		pointer to pmc_reg_map struct that contains platform
>>   *			specific attributes
>>   * @lpm_req_regs:	List of substate requirements
>> + * @ltr_ign:		Holds LTR ignore data while suspended
>>   *
>>   * pmc contains info about one power management controller device.
>>   */
>> @@ -380,6 +381,7 @@ struct pmc {
>>  	void __iomem *regbase;
>>  	const struct pmc_reg_map *map;
>>  	u32 *lpm_req_regs;
>> +	u32 ltr_ign;
>>  };
>>  
>>  /**
>