On Fri, 6 Sep 2024, Xi Pardee wrote:
> From: Xi Pardee <xi.pardee@xxxxxxxxx>
>
> 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@xxxxxxxxx>
> Signed-off-by: Xi Pardee <xi.pardee@xxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxx>
--
i.
