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List:       linux-tegra
Subject:    Re: [PATCH 1/4] PCI/ASPM: Add API to supply LTR L1.2 threshold
From:       Vidya Sagar <vidyas () nvidia ! com>
Date:       2017-10-30 17:24:32
Message-ID: 4cba6cf2-7805-27a9-2653-be4f5399cba8 () nvidia ! com
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On Monday 30 October 2017 10:25 PM, Rajat Jain wrote:
> On Mon, Oct 30, 2017 at 4:03 AM, Vidya Sagar <vidyas@nvidia.com> wrote:
>> adds API for host controller drivers to specify LTR L1.2
>> threshold value if it is different from the default value.
>> weak implementation of the API is added to supply default
>> value
>>
>> Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
>> ---
>>   drivers/pci/pcie/aspm.c  | 11 ++++++++---
>>   include/linux/pci-aspm.h |  6 ++++++
>>   2 files changed, 14 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
>> index 1dfa10cc566b..c6e8604796e5 100644
>> --- a/drivers/pci/pcie/aspm.c
>> +++ b/drivers/pci/pcie/aspm.c
>> @@ -436,6 +436,11 @@ static struct pci_dev *pci_function_0(struct pci_bus *linkbus)
>>          return NULL;
>>   }
>>
>> +u32 __weak pcie_aspm_get_ltr_l_1_2_threshold(void)
>> +{
>> +       return LTR_L1_2_THRESHOLD_BITS;
>> +}
>> +
>>   /* Calculate L1.2 PM substate timing parameters */
>>   static void aspm_calc_l1ss_info(struct pcie_link_state *link,
>>                                  struct aspm_register_info *upreg,
>> @@ -458,10 +463,10 @@ static void aspm_calc_l1ss_info(struct pcie_link_state *link,
>>          else
>>                  link->l1ss.ctl1 |= val2 << 8;
>>          /*
>> -        * We currently use LTR L1.2 threshold to be fixed constant picked from
>> -        * Intel's coreboot.
>> +        * Get LTR L1.2 threshold value specific to a platform if present
>> +        * Otherwise, get a constant value picked from Intel's coreboot.
>>           */
>> -       link->l1ss.ctl1 |= LTR_L1_2_THRESHOLD_BITS;
>> +       link->l1ss.ctl1 |= pcie_aspm_get_ltr_l_1_2_threshold();
>>
>>          /* Choose the greater of the two T_pwr_on */
>>          val1 = (upreg->l1ss_cap >> 19) & 0x1F;
>> diff --git a/include/linux/pci-aspm.h b/include/linux/pci-aspm.h
>> index 207c561fb40e..7ffde0f57688 100644
>> --- a/include/linux/pci-aspm.h
>> +++ b/include/linux/pci-aspm.h
>> @@ -30,6 +30,7 @@ void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
>>   void pci_disable_link_state(struct pci_dev *pdev, int state);
>>   void pci_disable_link_state_locked(struct pci_dev *pdev, int state);
>>   void pcie_no_aspm(void);
>> +u32 pcie_aspm_get_ltr_l_1_2_threshold(void);
>>   #else
>>   static inline void pcie_aspm_init_link_state(struct pci_dev *pdev)
>>   {
>> @@ -49,6 +50,11 @@ static inline void pci_disable_link_state(struct pci_dev *pdev, int state)
>>   static inline void pcie_no_aspm(void)
>>   {
>>   }
>> +
>> +static inline u32 pcie_aspm_get_ltr_l_1_2_threshold(void)
>> +{
>> +       return 0;
>> +}
> Do we really need this (bogus) function definition in
> !defined(CONFIG_PCIEASPM) case? I believe the other bogus definitions
> in that section are needed because functions outside of
> CONFIG_PCIEASPM call it.
I'll remove it in my next patch.
>>   #endif
>>
>>   #ifdef CONFIG_PCIEASPM_DEBUG /* this depends on CONFIG_PCIEASPM */
>> --
>> 2.7.4
>>

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