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Date: Thu, 26 Jan 2023 12:43:47 +0100
From: "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>
To: Vidya Sagar <vidyas@...dia.com>, <bhelgaas@...gle.com>,
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
<kai.heng.feng@...onical.com>
CC: <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<treding@...dia.com>, <jonathanh@...dia.com>, <kthota@...dia.com>,
<mmaddireddy@...dia.com>, <sagar.tv@...il.com>
Subject: Re: [PATCH V1] PCI/ASPM: Update saved buffers with latest ASPM
configuration
On 1/25/2023 6:22 PM, Vidya Sagar wrote:
>
>
> On 1/25/2023 8:31 PM, Wysocki, Rafael J wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> On 1/25/2023 2:38 PM, Vidya Sagar wrote:
>>> Many PCIe device drivers save the configuration state of their
>>> respective
>>> devices during probe and restore the same when their 'slot_reset' hook
>>> is called through PCIe Error Recovery System.
>>> If the system has a change in ASPM policy after the driver's probe is
>>> called and before error event occurred, 'slot_reset' hook restores the
>>> PCIe configuration state to what it was at the time of probe but not
>>> with
>>> what it was just before the occurrence of the error event.
>>> This effectively leads to a mismatch in the ASPM configuration between
>>> the device and its upstream parent device.
>>> This patch addresses that issue by updating the saved configuration
>>> state
>>> of the device with the latest info whenever there is a change w.r.t
>>> ASPM
>>> policy.
>>>
>>> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
>>
>> If it is a bug fix (which I think it is), a Fixes tag should be present
>> here.
>
> It is kind of a bug fix but I couldn't pin point to any particular
> commit that would have introduced it.
>
>>
>> If the reporter's names are known, Reported-by tags should be present
>> here too.
>
> I was experimenting with the error handling code and happen to find this.
>
>>
>> If anyone except for you has tested this patch, a Tested-by tag should
>> be present here.
>
> Only I tested this patch for now. It would be great if more
> verification is done on this patch.
>
Fair enough.
Please feel free to add
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
to this patch.
>
>>
>>> ---
>>> drivers/pci/pci.h | 4 ++++
>>> drivers/pci/pcie/aspm.c | 40 ++++++++++++++++++++++++++++++++++++++++
>>> 2 files changed, 44 insertions(+)
>>>
>>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
>>> index 9ed3b5550043..f4a91d4fe96d 100644
>>> --- a/drivers/pci/pci.h
>>> +++ b/drivers/pci/pci.h
>>> @@ -566,12 +566,16 @@ bool pcie_wait_for_link(struct pci_dev *pdev,
>>> bool active);
>>> void pcie_aspm_init_link_state(struct pci_dev *pdev);
>>> void pcie_aspm_exit_link_state(struct pci_dev *pdev);
>>> void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
>>> +void pci_save_aspm_state(struct pci_dev *dev);
>>> +void pci_restore_aspm_state(struct pci_dev *dev);
>>> void pci_save_aspm_l1ss_state(struct pci_dev *dev);
>>> void pci_restore_aspm_l1ss_state(struct pci_dev *dev);
>>> #else
>>> static inline void pcie_aspm_init_link_state(struct pci_dev *pdev)
>>> { }
>>> static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev)
>>> { }
>>> static inline void pcie_aspm_powersave_config_link(struct pci_dev
>>> *pdev) { }
>>> +static inline void pci_save_aspm_state(struct pci_dev *dev) { }
>>> +static inline void pci_restore_aspm_state(struct pci_dev *dev) { }
>>> static inline void pci_save_aspm_l1ss_state(struct pci_dev *dev) { }
>>> static inline void pci_restore_aspm_l1ss_state(struct pci_dev
>>> *dev) { }
>>> #endif
>>> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
>>> index 53a1fa306e1e..f25e0440d36b 100644
>>> --- a/drivers/pci/pcie/aspm.c
>>> +++ b/drivers/pci/pcie/aspm.c
>>> @@ -151,6 +151,7 @@ static void pcie_set_clkpm_nocheck(struct
>>> pcie_link_state *link, int enable)
>>> PCI_EXP_LNKCTL_CLKREQ_EN,
>>> val);
>>> link->clkpm_enabled = !!enable;
>>> + pci_save_aspm_state(child);
>>> }
>>>
>>> static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
>>> @@ -757,6 +758,39 @@ static void pcie_config_aspm_l1ss(struct
>>> pcie_link_state *link, u32 state)
>>> PCI_L1SS_CTL1_L1SS_MASK, val);
>>> }
>>>
>>> +void pci_save_aspm_state(struct pci_dev *dev)
>>> +{
>>> + int i = 0;
>>> + struct pci_cap_saved_state *save_state;
>>> + u16 *cap;
>>> +
>>> + if (!pci_is_pcie(dev))
>>> + return;
>>> +
>>> + save_state = pci_find_saved_cap(dev, PCI_CAP_ID_EXP);
>>> + if (!save_state)
>>> + return;
>>> +
>>> + cap = (u16 *)&save_state->cap.data[0];
>>> + i++;
>>> + pcie_capability_read_word(dev, PCI_EXP_LNKCTL, &cap[i++]);
>>> +}
>>> +
>>> +void pci_restore_aspm_state(struct pci_dev *dev)
>>> +{
>>> + int i = 0;
>>> + struct pci_cap_saved_state *save_state;
>>> + u16 *cap;
>>> +
>>> + save_state = pci_find_saved_cap(dev, PCI_CAP_ID_EXP);
>>> + if (!save_state)
>>> + return;
>>> +
>>> + cap = (u16 *)&save_state->cap.data[0];
>>> + i++;
>>> + pcie_capability_write_word(dev, PCI_EXP_LNKCTL, cap[i++]);
>>> +}
>>> +
>>> void pci_save_aspm_l1ss_state(struct pci_dev *dev)
>>> {
>>> struct pci_cap_saved_state *save_state;
>>> @@ -849,6 +883,12 @@ static void pcie_config_aspm_link(struct
>>> pcie_link_state *link, u32 state)
>>> pcie_config_aspm_dev(parent, upstream);
>>>
>>> link->aspm_enabled = state;
>>> +
>>> + /* Update latest ASPM configuration in saved context */
>>> + pci_save_aspm_state(link->downstream);
>>> + pci_save_aspm_l1ss_state(link->downstream);
>>> + pci_save_aspm_state(parent);
>>> + pci_save_aspm_l1ss_state(parent);
>>> }
>>>
>>> static void pcie_config_aspm_path(struct pcie_link_state *link)
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