linux-kernel - RE: [PATCH V3 2/2] PCI: dwc: Add support to configure for ECRC

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Date:   Mon, 2 Nov 2020 15:11:53 +0000
From:   Gustavo Pimentel <Gustavo.Pimentel@...opsys.com>
To:     Vidya Sagar <vidyas@...dia.com>, Rob Herring <robh@...nel.org>
CC:     Jingoo Han <jingoohan1@...il.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Andrew Murray <amurray@...goodpenguin.co.uk>,
        Thierry Reding <treding@...dia.com>,
        Jon Hunter <jonathanh@...dia.com>,
        PCI <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kthota@...dia.com" <kthota@...dia.com>,
        Manikanta Maddireddy <mmaddireddy@...dia.com>,
        "sagar.tv@...il.com" <sagar.tv@...il.com>
Subject: RE: [PATCH V3 2/2] PCI: dwc: Add support to configure for ECRC

On Mon, Nov 2, 2020 at 14:27:9, Vidya Sagar <vidyas@...dia.com> wrote:

> 
> 
> On 11/2/2020 7:45 PM, Rob Herring wrote:
> > External email: Use caution opening links or attachments
> > 
> > 
> > On Thu, Oct 29, 2020 at 12:40 AM Vidya Sagar <vidyas@...dia.com> wrote:
> >>
> >> DesignWare core has a TLP digest (TD) override bit in one of the control
> >> registers of ATU. This bit also needs to be programmed for proper ECRC
> >> functionality. This is currently identified as an issue with DesignWare
> >> IP version 4.90a. This patch does the required programming in ATU upon
> >> querying the system policy for ECRC.
> >>
> >> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
> >> Reviewed-by: Jingoo Han <jingoohan1@...il.com>
> >> ---
> >> V3:
> >> * Added 'Reviewed-by: Jingoo Han <jingoohan1@...il.com>'
> >>
> >> V2:
> >> * Addressed Jingoo's review comment
> >> * Removed saving 'td' bit information in 'dw_pcie' structure
> >>
> >>   drivers/pci/controller/dwc/pcie-designware.c | 8 ++++++--
> >>   drivers/pci/controller/dwc/pcie-designware.h | 1 +
> >>   2 files changed, 7 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> >> index b5e438b70cd5..cbd651b219d2 100644
> >> --- a/drivers/pci/controller/dwc/pcie-designware.c
> >> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> >> @@ -246,6 +246,8 @@ static void dw_pcie_prog_outbound_atu_unroll(struct dw_pcie *pci, u8 func_no,
> >>          dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_UPPER_TARGET,
> >>                                   upper_32_bits(pci_addr));
> >>          val = type | PCIE_ATU_FUNC_NUM(func_no);
> >> +       if (pci->version == 0x490A)
> >> +               val = val | pcie_is_ecrc_enabled() << PCIE_ATU_TD_SHIFT;
> >>          val = upper_32_bits(size - 1) ?
> >>                  val | PCIE_ATU_INCREASE_REGION_SIZE : val;
> >>          dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_REGION_CTRL1, val);
> >> @@ -294,8 +296,10 @@ static void __dw_pcie_prog_outbound_atu(struct dw_pcie *pci, u8 func_no,
> >>                             lower_32_bits(pci_addr));
> >>          dw_pcie_writel_dbi(pci, PCIE_ATU_UPPER_TARGET,
> >>                             upper_32_bits(pci_addr));
> >> -       dw_pcie_writel_dbi(pci, PCIE_ATU_CR1, type |
> >> -                          PCIE_ATU_FUNC_NUM(func_no));
> >> +       val = type | PCIE_ATU_FUNC_NUM(func_no);
> >> +       if (pci->version == 0x490A)
> > 
> > Is this even possible? Are the non-unroll ATU registers available post 4.80?
> I'm not sure. Gustavo might have information about this. I made this 
> change so that it is taken care off even if they available.

The Synopsys DesignWare PCIe IP is highly configurable, therefore is 
dependable on what the design team has configured for their solution.
Although Synopsys doesn't recommend the use of non-unroll ATU, the 
customers are free to select what they want for their design.

-Gustavo

> 
> > 
> > Rob
> >