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Date:   Fri, 15 Oct 2021 20:08:18 +0530
From:   Naveen Naidu <naveennaidu479@gmail.com>
To:     bhelgaas@google.com
Cc:     linux-kernel-mentees@lists.linuxfoundation.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-hyperv@vger.kernel.org,
        linux-mediatek@lists.infradead.org, linuxppc-dev@lists.ozlabs.org,
        linux-renesas-soc@vger.kernel.org,
        linux-rockchip@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org, Rob Herring <robh@kernel.org>,
        Pali =?utf-8?B?Um9ow6Fy?= <pali@kernel.org>
Subject: Re: [PATCH v2 00/24] Unify PCI error response checking
Message-ID: <20211015143818.gvkcs5j6zvdino2r@theprophet>
References: <cover.1634300660.git.naveennaidu479@gmail.com>
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On 15/10, Naveen Naidu wrote:
> An MMIO read from a PCI device that doesn't exist or doesn't respond
> causes a PCI error.  There's no real data to return to satisfy the 
> CPU read, so most hardware fabricates ~0 data.
> 
> This patch series adds PCI_ERROR_RESPONSE definition and other helper
> definition SET_PCI_ERROR_RESPONSE and RESPONSE_IS_PCI_ERROR and uses it
> where appropriate to make these checks consistent and easier to find.
> 
> This helps unify PCI error response checking and make error check
> consistent and easier to find.
> 
> This series also ensures that the error response fabrication now happens
> in the PCI_OP_READ and PCI_USER_READ_CONFIG. This removes the
> responsibility from controller drivers to do the error response setting. 
> 
> Patch 1:
>     - Adds the PCI_ERROR_RESPONSE and other related defintions
>     - All other patches are dependent on this patch. This patch needs to
>       be applied first, before the others
> 
> Patch 2:
>     - Error fabrication happens in PCI_OP_READ and PCI_USER_READ_CONFIG
>       whenever the data read via the controller driver fails.
>     - This patch needs to be applied before, Patch 4/24 to Patch 15/24 are
>       applied.
> 
> Patch 3:
>     - Uses SET_PCI_ERROR_RESPONSE() when device is not found and
>       RESPONSE_IS_PCI_ERROR() to check hardware read from the hardware.
> 
> Patch 4 - 15:
>     - Removes redundant error fabrication that happens in controller 
>       drivers when the read from a PCI device fails.
>     - These patches are dependent on Patch 2/24 of the series.
>     - These can be applied in any order.
> 
> Patch 16 - 22:
>     - Uses RESPONSE_IS_PCI_ERROR() to check the reads from hardware
>     - Patches can be applied in any order.
> 
> Patch 23 - 24:
>     - Edits the comments to include PCI_ERROR_RESPONSE alsong with
>       0xFFFFFFFF, so that it becomes easier to grep for faulty 
>       hardware reads.
> 
> Changelog
> =========
> 
> v2:
>     - Instead of using SET_PCI_ERROR_RESPONSE in all controller drivers
>       to fabricate error response, only use them in PCI_OP_READ and
>       PCI_USER_READ_CONFIG
> 
> Naveen Naidu (24):
>  [PATCH 1/24] PCI: Add PCI_ERROR_RESPONSE and it's related definitions
>  [PATCH 2/24] PCI: Set error response in config access defines when ops->read() fails
>  [PATCH 3/24] PCI: Unify PCI error response checking
>  [PATCH 4/24] PCI: Remove redundant error fabrication when device read fails
>  [PATCH 5/24] PCI: thunder: Remove redundant error fabrication when device read fails
>  [PATCH 6/24] PCI: iproc: Remove redundant error fabrication when device read fails
>  [PATCH 7/24] PCI: mediatek: Remove redundant error fabrication when device read fails
>  [PATCH 8/24] PCI: exynos: Remove redundant error fabrication when device read fails
>  [PATCH 9/24] PCI: histb: Remove redundant error fabrication when device read fails
>  [PATCH 10/24] PCI: kirin: Remove redundant error fabrication when device read fails
>  [PATCH 11/24] PCI: aardvark: Remove redundant error fabrication when device read fails
>  [PATCH 12/24] PCI: mvebu: Remove redundant error fabrication when device read fails
>  [PATCH 13/24] PCI: altera: Remove redundant error fabrication when device read fails
>  [PATCH 14/24] PCI: rcar: Remove redundant error fabrication when device read fails
>  [PATCH 15/24] PCI: rockchip: Remove redundant error fabrication when device read fails
>  [PATCH 16/24] PCI/ERR: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
>  [PATCH 17/24] PCI: vmd: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
>  [PATCH 18/24] PCI: pciehp: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
>  [PATCH 19/24] PCI/DPC: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
>  [PATCH 20/24] PCI/PME: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
>  [PATCH 21/24] PCI: cpqphp: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
>  [PATCH 22/24] PCI: keystone: Use PCI_ERROR_RESPONSE to specify hardware error
>  [PATCH 23/24] PCI: hv: Use PCI_ERROR_RESPONSE to specify hardware read error
>  [PATCH 24/24] PCI: xgene: Use PCI_ERROR_RESPONSE to specify hardware error
> 
>  drivers/pci/access.c                        | 36 ++++++++--------
>  drivers/pci/controller/dwc/pci-exynos.c     |  4 +-
>  drivers/pci/controller/dwc/pci-keystone.c   |  4 +-
>  drivers/pci/controller/dwc/pcie-histb.c     |  4 +-
>  drivers/pci/controller/dwc/pcie-kirin.c     |  4 +-
>  drivers/pci/controller/pci-aardvark.c       | 10 +----
>  drivers/pci/controller/pci-hyperv.c         |  2 +-
>  drivers/pci/controller/pci-mvebu.c          |  8 +---
>  drivers/pci/controller/pci-thunder-ecam.c   | 46 +++++++--------------
>  drivers/pci/controller/pci-thunder-pem.c    |  4 +-
>  drivers/pci/controller/pci-xgene.c          |  8 ++--
>  drivers/pci/controller/pcie-altera.c        |  4 +-
>  drivers/pci/controller/pcie-iproc.c         |  4 +-
>  drivers/pci/controller/pcie-mediatek.c      | 11 +----
>  drivers/pci/controller/pcie-rcar-host.c     |  4 +-
>  drivers/pci/controller/pcie-rockchip-host.c |  4 +-
>  drivers/pci/controller/vmd.c                |  2 +-
>  drivers/pci/hotplug/cpqphp_ctrl.c           |  4 +-
>  drivers/pci/hotplug/pciehp_hpc.c            | 10 ++---
>  drivers/pci/pci.c                           | 10 ++---
>  drivers/pci/pcie/dpc.c                      |  4 +-
>  drivers/pci/pcie/pme.c                      |  4 +-
>  drivers/pci/probe.c                         | 10 ++---
>  include/linux/pci.h                         |  9 ++++
>  24 files changed, 87 insertions(+), 123 deletions(-)
> 
> -- 
> 2.25.1
>

Please ignore this stray cover letter. I had a wrong message ID written
for it. Apologies for the inconvenience caused.