linux-kernel - Re: [PATCH v4 6/7] PCI: Add TLP Prefix reading into pcie_read_tlp

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Message-ID: <7d69ae9f-9d2f-2482-eaa7-d3e31037c8d1@linux.intel.com>
Date: Fri, 10 May 2024 15:12:47 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>
cc: Mahesh J Salgaonkar <mahesh@...ux.ibm.com>, 
    Oliver O'Halloran <oohall@...il.com>, Lukas Wunner <lukas@...ner.de>, 
    LKML <linux-kernel@...r.kernel.org>, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v4 6/7] PCI: Add TLP Prefix reading into
 pcie_read_tlp_log()

On Fri, 10 May 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.
> 
> 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@...ux.intel.com>
> ---
>  drivers/pci/pci.h             |  5 +++-
>  drivers/pci/pcie/aer.c        |  4 ++-
>  drivers/pci/pcie/dpc.c        | 13 +++++-----
>  drivers/pci/pcie/tlp.c        | 47 +++++++++++++++++++++++++++++++----
>  include/linux/aer.h           |  1 +
>  include/uapi/linux/pci_regs.h |  1 +
>  6 files changed, 57 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 0e9917f8bf3f..3d9034d89be8 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -420,7 +420,10 @@ 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);
> +unsigned int dpc_tlp_log_len(struct pci_dev *dev);
>  #endif	/* CONFIG_PCIEAER */
>  
>  #ifdef CONFIG_PCIEPORTBUS
> diff --git a/drivers/pci/pcie/tlp.c b/drivers/pci/pcie/tlp.c
> index 65ac7b5d8a87..3615ca520c9a 100644
> --- a/drivers/pci/pcie/tlp.c
> +++ b/drivers/pci/pcie/tlp.c
> @@ -11,26 +11,63 @@
>  
>  #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)
> +{
> +	return 4 + dev->eetlp_prefix_max;
> +}
> +
> +/**
> + * dpc_tlp_log_len - Calculates DPC RP PIO TLP Header/Prefix Log length
> + * @dev: PCIe device
> + *
> + * Return: TLP Header/Prefix Log length
> + */
> +unsigned int dpc_tlp_log_len(struct pci_dev *pdev)
> +{
> +	/* Remove ImpSpec Log register from the count */
> +	if (pdev->dpc_rp_log_size >= 5)

Scratch this. LKP's randconfig build seems to have caught this failing to 
build when AER is enabled but DPC is not because this member doesn't exist 
w/o DPC.

> +		return pdev->dpc_rp_log_size - 1;
> +
> +	return pdev->dpc_rp_log_size;
> +}


-- 
 i.