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

[Xi Pardee <xi.pardee@linux.intel.com>]

Hi,

On 9/9/2024 1:07 AM, Ilpo Järvinen wrote:
> On Fri, 6 Sep 2024, 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>
>>
>> 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;
>>   };
>>   
>>   /**
>>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Thanks for the Reviewed-by tag! I wonder if I need to send another 
version with the Reviewed-by tag for this patch to be accepted.

Thanks!

Xi