Re: [PATCH] PCI/AER: save/restore AER registers during suspend/resume

[sathyanarayanan kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>]

Hi,

On 7/9/19 1:00 AM, Patel, Mayurkumar wrote:
> After system suspend/resume cycle AER registers settings are
> lost. Not restoring Root Error Command Register bits if it were
> set, keeps AER interrupts disabled after system resume.
> Moreover, AER mask and severity registers are also required
> to be restored back to AER settings prior to system suspend.
>
> Signed-off-by: Mayurkumar Patel <mayurkumar.patel@intel.com>
> ---
>   drivers/pci/pci.c      |  2 ++
>   drivers/pci/pcie/aer.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
>   include/linux/aer.h    |  4 ++++
>   3 files changed, 55 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 8abc843..40d5507 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1340,6 +1340,7 @@ int pci_save_state(struct pci_dev *dev)
>   
>   	pci_save_ltr_state(dev);
>   	pci_save_dpc_state(dev);
> +	pci_save_aer_state(dev);
>   	return pci_save_vc_state(dev);
>   }
>   EXPORT_SYMBOL(pci_save_state);
> @@ -1453,6 +1454,7 @@ void pci_restore_state(struct pci_dev *dev)
>   	pci_restore_dpc_state(dev);
>   
>   	pci_cleanup_aer_error_status_regs(dev);
> +	pci_restore_aer_state(dev);
>   
>   	pci_restore_config_space(dev);
>   
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index b45bc47..1acc641 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -448,6 +448,54 @@ int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
>   	return 0;
>   }
>   
> +void pci_save_aer_state(struct pci_dev *dev)
> +{
> +	int pos = 0;
> +	struct pci_cap_saved_state *save_state;
> +	u32 *cap;
> +
> +	if (!pci_is_pcie(dev))
> +		return;
> +
> +	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_ERR);
> +	if (!save_state)
> +		return;
> +
> +	pos = dev->aer_cap;
> +	if (!pos)
> +		return;
> +
> +	cap = &save_state->cap.data[0];
> +	pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_MASK, cap++);
> +	pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_SEVER, cap++);
> +	pci_read_config_dword(dev, pos + PCI_ERR_COR_MASK, cap++);
> +	pci_read_config_dword(dev, pos + PCI_ERR_ROOT_COMMAND, cap++);

I don't see AER driver modifying UNCOR_MASK/SEVER/COR_MASK register. If 
all it has is default value then why do you want to preserve it ?

Also, any reason for not preserving ECRC settings ?

> +}
> +
> +void pci_restore_aer_state(struct pci_dev *dev)
> +{
> +	int pos = 0;
> +	struct pci_cap_saved_state *save_state;
> +	u32 *cap;
> +
> +	if (!pci_is_pcie(dev))
> +		return;
> +
> +	save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_ERR);
> +	if (!save_state)
> +		return;
> +
> +	pos = dev->aer_cap;
> +	if (!pos)
> +		return;
> +
> +	cap = &save_state->cap.data[0];
> +	pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_MASK, *cap++);
> +	pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_SEVER, *cap++);
> +	pci_write_config_dword(dev, pos + PCI_ERR_COR_MASK, *cap++);
> +	pci_write_config_dword(dev, pos + PCI_ERR_ROOT_COMMAND, *cap++);
> +}
> +
>   void pci_aer_init(struct pci_dev *dev)
>   {
>   	dev->aer_cap = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
> @@ -1396,6 +1444,7 @@ static int aer_probe(struct pcie_device *dev)
>   		return status;
>   	}
>   
> +	pci_add_ext_cap_save_buffer(port, PCI_EXT_CAP_ID_ERR, sizeof(u32) * 4);
>   	aer_enable_rootport(rpc);
>   	pci_info(port, "enabled with IRQ %d\n", dev->irq);
>   	return 0;
> diff --git a/include/linux/aer.h b/include/linux/aer.h
> index 514bffa..fa19e01 100644
> --- a/include/linux/aer.h
> +++ b/include/linux/aer.h
> @@ -46,6 +46,8 @@ int pci_enable_pcie_error_reporting(struct pci_dev *dev);
>   int pci_disable_pcie_error_reporting(struct pci_dev *dev);
>   int pci_cleanup_aer_uncorrect_error_status(struct pci_dev *dev);
>   int pci_cleanup_aer_error_status_regs(struct pci_dev *dev);
> +void pci_save_aer_state(struct pci_dev *dev);
> +void pci_restore_aer_state(struct pci_dev *dev);
>   #else
>   static inline int pci_enable_pcie_error_reporting(struct pci_dev *dev)
>   {
> @@ -63,6 +65,8 @@ static inline int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
>   {
>   	return -EINVAL;
>   }
> +static inline void pci_save_aer_state(struct pci_dev *dev) {}
> +static inline void pci_restore_aer_state(struct pci_dev *dev) {}
>   #endif
>   
>   void cper_print_aer(struct pci_dev *dev, int aer_severity,

-- 
Sathyanarayanan Kuppuswamy
Linux kernel developer