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Date:   Wed, 10 Aug 2022 15:30:23 -0600
From:   Rob Herring <robh@kernel.org>
To:     Will McVicker <willmcvicker@google.com>
Cc:     Jingoo Han <jingoohan1@gmail.com>,
        Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
        Bjorn Helgaas <bhelgaas@google.com>, kernel-team@android.com,
        Vidya Sagar <vidyas@nvidia.com>,
        kernel test robot <lkp@intel.com>,
        "Isaac J . Manjarres" <isaacmanjarres@google.com>,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] PCI: dwc: add support for 64-bit MSI target
 address
Message-ID: <20220810213023.GB557589-robh@kernel.org>
References: <20220810183536.1630940-1-willmcvicker@google.com>
 <20220810183536.1630940-3-willmcvicker@google.com>
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On Wed, Aug 10, 2022 at 06:35:35PM +0000, Will McVicker wrote:
> Since not all devices require a 32-bit MSI address, add support to the
> PCIe host driver to allow setting the DMA mask to 64-bits. This allows
> kernels to disable ZONE_DMA32 and bounce buffering (swiotlb) without
> risking not being able to get a 32-bit address during DMA allocation.
> Basically, in the slim chance that there are no 32-bit allocations
> available, the current PCIe host driver will fail to allocate the
> msi_msg page due to a DMA address overflow (seen in [1]). With this
> patch, the PCIe driver can advertise 64-bit support via it's MSI
> capabilities to hint to the PCIe host driver to set the DMA mask to
> 64-bits.
> 
> [1] https://lore.kernel.org/all/Yo0soniFborDl7+C@google.com/
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Will McVicker <willmcvicker@google.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 14 ++++++++++++--
>  drivers/pci/controller/dwc/pcie-designware.c      |  9 +++++++++
>  drivers/pci/controller/dwc/pcie-designware.h      |  1 +
>  3 files changed, 22 insertions(+), 2 deletions(-)

Reviewed-by: Rob Herring <robh@kernel.org>