Re: [PATCH v7 6/8] PCI: Add TLP Prefix reading into pcie_read_tlp_log()

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

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On Tue, 17 Dec 2024, Ilpo Järvinen wrote:

> pcie_read_tlp_log() handles only 4 Header Log DWORDs but TLP Prefix Log
> (PCIe r6.1 secs 7.8.4.12 & 7.9.14.13) may also be present.
> 
> Generalize pcie_read_tlp_log() and struct pcie_tlp_log to handle also
> TLP Prefix Log. The relevant registers are formatted identically in AER
> and DPC Capability, but has these variations:
> 
> a) The offsets of TLP Prefix Log registers vary.
> b) DPC RP PIO TLP Prefix Log register can be < 4 DWORDs.
> c) AER TLP Prefix Log Present (PCIe r6.1 sec 7.8.4.7) can indicate
>    Prefix Log is not present.
> 
> Therefore callers must pass the offset of the TLP Prefix Log register
> and the entire length to pcie_read_tlp_log() to be able to read the
> correct number of TLP Prefix DWORDs from the correct offset.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---
>  drivers/pci/pci.h             |  5 +++-
>  drivers/pci/pcie/aer.c        |  5 +++-
>  drivers/pci/pcie/dpc.c        | 13 +++++----
>  drivers/pci/pcie/tlp.c        | 50 +++++++++++++++++++++++++++++++----
>  include/linux/aer.h           |  1 +
>  include/uapi/linux/pci_regs.h | 10 ++++---
>  6 files changed, 66 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 55fcf3bac4f7..7797b2544d00 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -550,7 +550,9 @@ struct aer_err_info {
>  int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info);
>  void aer_print_error(struct pci_dev *dev, struct aer_err_info *info);
>  
> -int pcie_read_tlp_log(struct pci_dev *dev, int where, struct pcie_tlp_log *log);
> +int pcie_read_tlp_log(struct pci_dev *dev, int where, int where2,
> +		      unsigned int tlp_len, struct pcie_tlp_log *log);
> +unsigned int aer_tlp_log_len(struct pci_dev *dev, u32 aercc);
>  #endif	/* CONFIG_PCIEAER */
>  
>  #ifdef CONFIG_PCIEPORTBUS
> @@ -569,6 +571,7 @@ void pci_dpc_init(struct pci_dev *pdev);
>  void dpc_process_error(struct pci_dev *pdev);
>  pci_ers_result_t dpc_reset_link(struct pci_dev *pdev);
>  bool pci_dpc_recovered(struct pci_dev *pdev);
> +unsigned int dpc_tlp_log_len(struct pci_dev *dev);
>  #else
>  static inline void pci_save_dpc_state(struct pci_dev *dev) { }
>  static inline void pci_restore_dpc_state(struct pci_dev *dev) { }
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index 80c5ba8d8296..656dbf1ac45b 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -1248,7 +1248,10 @@ int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info)
>  
>  		if (info->status & AER_LOG_TLP_MASKS) {
>  			info->tlp_header_valid = 1;
> -			pcie_read_tlp_log(dev, aer + PCI_ERR_HEADER_LOG, &info->tlp);
> +			pcie_read_tlp_log(dev, aer + PCI_ERR_HEADER_LOG,
> +					  aer + PCI_ERR_PREFIX_LOG,
> +					  aer_tlp_log_len(dev, aercc),
> +					  &info->tlp);
>  		}
>  	}
>  
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index 2b6ef7efa3c1..7933b3cedb59 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -190,7 +190,7 @@ pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
>  static void dpc_process_rp_pio_error(struct pci_dev *pdev)
>  {
>  	u16 cap = pdev->dpc_cap, dpc_status, first_error;
> -	u32 status, mask, sev, syserr, exc, log, prefix;
> +	u32 status, mask, sev, syserr, exc, log;
>  	struct pcie_tlp_log tlp_log;
>  	int i;
>  
> @@ -217,20 +217,19 @@ static void dpc_process_rp_pio_error(struct pci_dev *pdev)
>  
>  	if (pdev->dpc_rp_log_size < 4)
>  		goto clear_status;
> -	pcie_read_tlp_log(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG, &tlp_log);
> +	pcie_read_tlp_log(pdev, cap + PCI_EXP_DPC_RP_PIO_HEADER_LOG,
> +			  cap + PCI_EXP_DPC_RP_PIO_TLPPREFIX_LOG,
> +			  dpc_tlp_log_len(pdev), &tlp_log);
>  	pci_err(pdev, "TLP Header: %#010x %#010x %#010x %#010x\n",
>  		tlp_log.dw[0], tlp_log.dw[1], tlp_log.dw[2], tlp_log.dw[3]);
> +	for (i = 0; i < pdev->dpc_rp_log_size - 5; i++)
> +		pci_err(pdev, "TLP Prefix Header: dw%d, %#010x\n", i, tlp_log.prefix[i]);
>  
>  	if (pdev->dpc_rp_log_size < 5)
>  		goto clear_status;
>  	pci_read_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_IMPSPEC_LOG, &log);
>  	pci_err(pdev, "RP PIO ImpSpec Log %#010x\n", log);
>  
> -	for (i = 0; i < pdev->dpc_rp_log_size - 5; i++) {
> -		pci_read_config_dword(pdev,
> -			cap + PCI_EXP_DPC_RP_PIO_TLPPREFIX_LOG + i * 4, &prefix);
> -		pci_err(pdev, "TLP Prefix Header: dw%d, %#010x\n", i, prefix);
> -	}
>   clear_status:
>  	pci_write_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_STATUS, status);
>  }
> diff --git a/drivers/pci/pcie/tlp.c b/drivers/pci/pcie/tlp.c
> index 65ac7b5d8a87..0c4bf6a50d7e 100644
> --- a/drivers/pci/pcie/tlp.c
> +++ b/drivers/pci/pcie/tlp.c
> @@ -11,26 +11,66 @@
>  
>  #include "../pci.h"
>  
> +/**
> + * aer_tlp_log_len - Calculates AER Capability TLP Header/Prefix Log length
> + * @dev: PCIe device
> + *
> + * Return: TLP Header/Prefix Log length
> + */
> +unsigned int aer_tlp_log_len(struct pci_dev *dev, u32 aercc)

Hmpf, it seems I forgot to move the @aercc kerneldoc from Flit mode series 
patch were it was originally added to here when I needed aercc to the
PCI_ERR_CAP_PREFIX_LOG_PRESENT check.

I'll send an update in a day or two.

> +{
> +	return 4 + (aercc & PCI_ERR_CAP_PREFIX_LOG_PRESENT) ?
> +		   dev->eetlp_prefix_max : 0;
> +}

--
 i.