linux-kernel - Re: [PATCH V4] PCI/ASPM: Update saved buffers with latest ASPM

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Date: Thu, 22 Feb 2024 11:54:24 -0800
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Vidya Sagar <vidyas@...dia.com>, bhelgaas@...gle.com, macro@...am.me.uk,
 ajayagarwal@...gle.com, ilpo.jarvinen@...ux.intel.com,
 david.e.box@...ux.intel.com, hkallweit1@...il.com, johan+linaro@...nel.org,
 xueshuai@...ux.alibaba.com, 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 V4] PCI/ASPM: Update saved buffers with latest ASPM


On 2/22/24 10:54 AM, Bjorn Helgaas wrote:
> On Thu, Feb 22, 2024 at 10:20:06AM -0800, Kuppuswamy Sathyanarayanan wrote:
>> On 2/22/24 9:44 AM, 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 Handler.
>>>
>>> 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 to
>>> 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.
>>>
>>> Update 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>
>>> ---
>>> V4:
>>> * Rebased on top of pci/aspm branch
>>>
>>> V3:
>>> * Addressed sathyanarayanan.kuppuswamy's review comments
>>>
>>> V2:
>>> * Rebased on top of the tree code
>>> * Addressed Bjorn's review comments
>>>
>>>  drivers/pci/pcie/aspm.c | 28 ++++++++++++++++++++++++++--
>>>  3 files changed, 28 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>>> index cfc5b84dc9c9..3db606ba9344 100644
>>> --- a/drivers/pci/pci.c
>>> +++ b/drivers/pci/pci.c
>>> @@ -1648,7 +1648,7 @@ static int pci_save_pcie_state(struct pci_dev *dev)
>>>  	pcie_capability_read_word(dev, PCI_EXP_LNKCTL2, &cap[i++]);
>>>  	pcie_capability_read_word(dev, PCI_EXP_SLTCTL2, &cap[i++]);
>>>  
>>> -	pci_save_aspm_state(dev);
>>> +	pci_save_aspm_l1ss_state(dev);
>>>  	pci_save_ltr_state(dev);
>>>  
>>>  	return 0;
>>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
>>> index b217e74966eb..9fe78eb8b07d 100644
>>> --- a/drivers/pci/pci.h
>>> +++ b/drivers/pci/pci.h
>>> @@ -95,7 +95,7 @@ void pci_msix_init(struct pci_dev *dev);
>>>  bool pci_bridge_d3_possible(struct pci_dev *dev);
>>>  void pci_bridge_d3_update(struct pci_dev *dev);
>>>  void pci_aspm_get_l1ss(struct pci_dev *pdev);
>>> -void pci_save_aspm_state(struct pci_dev *pdev);
>>> +void pci_save_aspm_l1ss_state(struct pci_dev *pdev);
>> is this rename a review request? It is not clear from the commit log
>> why you are doing it?
> David's changes already on pci/aspm added pci_save_aspm_state(), but
> it actually only saves L1SS data, and Vidya needs to save the non-L1SS
> data also.
>
> I think I'm going to rework David's changes a little bit so this is
> named pci_save_aspm_l1ss_state() from the beginning so we won't need
> the rename here.

Got it.

Change wise, this patch looks fine to me.

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>

>
> Bjorn

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer