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SubjectRe: [PATCH] PCI: Add PCIE ACS quirk for IPROC PAXB
Hi Bjorn,

Thank you for the improvements. With the changes, comments and commit
message exactly describes the purpose.
I tested the code changes and works fine.

Thanks again,
Srinath

On Fri, Sep 6, 2019 at 3:56 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> [+cc Alex]
>
> On Tue, Aug 20, 2019 at 10:09:45AM +0530, Srinath Mannam wrote:
> > From: Abhinav Ratna <abhinav.ratna@broadcom.com>
> >
> > IPROC PAXB RC doesn't support ACS capabilities and control registers.
> > Add quirk to have separate IOMMU groups for all EPs and functions connected
> > to root port, by masking RR/CR/SV/UF bits.
> >
> > Signed-off-by: Abhinav Ratna <abhinav.ratna@broadcom.com>
> > Signed-off-by: Srinath Mannam <srinath.mannam@broadcom.com>
>
> I tentatively applied this to pci/misc with Scott's ack for v5.4.
>
> I tweaked the patch itself to follow the style of similar quirks
> (interdiff is below, plus a diff of the commit log). Please make sure
> I didn't break it.
>
> I also went out on a limb and reworded the comment to give what I
> *think* is the justification for this patch, as opposed to merely a
> description of the code. I'm making a lot of assumptions there, so
> please confirm that they're correct, or supply alternate justification
> if they're not.
>
> > ---
> > drivers/pci/quirks.c | 16 ++++++++++++++++
> > 1 file changed, 16 insertions(+)
> >
> > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> > index 0f16acc..f9584c0 100644
> > --- a/drivers/pci/quirks.c
> > +++ b/drivers/pci/quirks.c
> > @@ -4466,6 +4466,21 @@ static int pci_quirk_mf_endpoint_acs(struct pci_dev *dev, u16 acs_flags)
> > return acs_flags ? 0 : 1;
> > }
> >
> > +static int pcie_quirk_brcm_bridge_acs(struct pci_dev *dev, u16 acs_flags)
> > +{
> > + /*
> > + * IPROC PAXB RC doesn't support ACS capabilities and control registers.
> > + * Add quirk to to have separate IOMMU groups for all EPs and functions
> > + * connected to root port, by masking RR/CR/SV/UF bits.
> > + */
> > +
> > + u16 flags = (PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF | PCI_ACS_SV);
> > + int ret = acs_flags & ~flags ? 0 : 1;
> > +
> > + return ret;
> > +}
> > +
> > +
> > static const struct pci_dev_acs_enabled {
> > u16 vendor;
> > u16 device;
> > @@ -4559,6 +4574,7 @@ static const struct pci_dev_acs_enabled {
> > { PCI_VENDOR_ID_AMPERE, 0xE00A, pci_quirk_xgene_acs },
> > { PCI_VENDOR_ID_AMPERE, 0xE00B, pci_quirk_xgene_acs },
> > { PCI_VENDOR_ID_AMPERE, 0xE00C, pci_quirk_xgene_acs },
> > + { PCI_VENDOR_ID_BROADCOM, 0xD714, pcie_quirk_brcm_bridge_acs },
> > { 0 }
> > };
>
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 77c0330ac922..2edbce35e8c5 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -4466,21 +4466,19 @@ static int pci_quirk_mf_endpoint_acs(struct pci_dev *dev, u16 acs_flags)
> return acs_flags ? 0 : 1;
> }
>
> -static int pcie_quirk_brcm_bridge_acs(struct pci_dev *dev, u16 acs_flags)
> +static int pci_quirk_brcm_acs(struct pci_dev *dev, u16 acs_flags)
> {
> /*
> - * IPROC PAXB RC doesn't support ACS capabilities and control registers.
> - * Add quirk to to have separate IOMMU groups for all EPs and functions
> - * connected to root port, by masking RR/CR/SV/UF bits.
> + * iProc PAXB Root Ports don't advertise an ACS capability, but
> + * they do not allow peer-to-peer transactions between Root Ports.
> + * Allow each Root Port to be in a separate IOMMU group by masking
> + * SV/RR/CR/UF bits.
> */
> + acs_flags &= ~(PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF);
>
> - u16 flags = (PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF | PCI_ACS_SV);
> - int ret = acs_flags & ~flags ? 0 : 1;
> -
> - return ret;
> + return acs_flags ? 0 : 1;
> }
>
> -
> static const struct pci_dev_acs_enabled {
> u16 vendor;
> u16 device;
> @@ -4574,7 +4572,7 @@ static const struct pci_dev_acs_enabled {
> { PCI_VENDOR_ID_AMPERE, 0xE00A, pci_quirk_xgene_acs },
> { PCI_VENDOR_ID_AMPERE, 0xE00B, pci_quirk_xgene_acs },
> { PCI_VENDOR_ID_AMPERE, 0xE00C, pci_quirk_xgene_acs },
> - { PCI_VENDOR_ID_BROADCOM, 0xD714, pcie_quirk_brcm_bridge_acs },
> + { PCI_VENDOR_ID_BROADCOM, 0xD714, pci_quirk_brcm_acs },
> { 0 }
> };
>
>
>
>
> @@ -1,49 +1,49 @@
> -commit b50ae502eff0
> +commit 46b2c32df7a4
> Author: Abhinav Ratna <abhinav.ratna@broadcom.com>
> Date: Tue Aug 20 10:09:45 2019 +0530
>
> - PCI: Add PCIE ACS quirk for IPROC PAXB
> + PCI: Add ACS quirk for iProc PAXB
>
> - IPROC PAXB RC doesn't support ACS capabilities and control registers.
> - Add quirk to have separate IOMMU groups for all EPs and functions connected
> - to root port, by masking RR/CR/SV/UF bits.
> + iProc PAXB Root Ports don't advertise an ACS capability, but they do not
> + allow peer-to-peer transactions between Root Ports. Add an ACS quirk so
> + each Root Port can be in a separate IOMMU group.
>
> + [bhelgaas: commit log, comment, use common implementation style]
> Link: https://lore.kernel.org/r/1566275985-25670-1-git-send-email-srinath.mannam@broadcom.com
> Signed-off-by: Abhinav Ratna <abhinav.ratna@broadcom.com>
> Signed-off-by: Srinath Mannam <srinath.mannam@broadcom.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> + Acked-by: Scott Branden <scott.branden@broadcom.com>
>

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