From: Pankaj Dubey <pankaj.dubey@samsung.com>
To: Andrew Murray <andrew.murray@arm.com>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
Jingoo Han <jingoohan1@gmail.com>,
gustavo.pimentel@synopsys.com, lorenzo.pieralisi@arm.com,
Bjorn Helgaas <bhelgaas@google.com>,
Anvesh Salveru <anvesh.s@samsung.com>
Subject: Re: [PATCH 2/2] PCI: dwc: Add support to disable equalization phase 2 and 3
Date: Tue, 10 Sep 2019 21:51:41 +0530 [thread overview]
Message-ID: <CAGcde9Fm+WGamjAC6R4jmaShMYxAoCsofggfwdJ7viYt3NE_sQ@mail.gmail.com> (raw)
In-Reply-To: <20190910140502.GL9720@e119886-lin.cambridge.arm.com>
On Tue, 10 Sep 2019 at 19:59, Andrew Murray <andrew.murray@arm.com> wrote:
>
> On Tue, Sep 10, 2019 at 05:55:02PM +0530, Pankaj Dubey wrote:
> > From: Anvesh Salveru <anvesh.s@samsung.com>
> >
> > In some platforms, PCIe PHY may have issues which will prevent linkup
> > to happen in GEN3 or high speed. In case equalization fails, link will
> > fallback to GEN1.
> >
> > Designware controller gives flexibility to disable GEN3 equalization
> > completely or only phase 2 and 3.
>
> Do some platforms have issues conducting phase 2 and 3 when they successfully
> conduct phase 0 and 1?
>
Yes, it is possible.
> >
> > Platform drivers can disable equalization phase 2 and 3, by setting
> > dwc_pci_quirk flag DWC_EQUALIZATION_DISABLE.
> >
> > Signed-off-by: Anvesh Salveru <anvesh.s@samsung.com>
> > Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
> > ---
> > drivers/pci/controller/dwc/pcie-designware.c | 3 +++
> > drivers/pci/controller/dwc/pcie-designware.h | 2 ++
> > 2 files changed, 5 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> > index bf82091..97a8268 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -472,5 +472,8 @@ void dw_pcie_setup(struct dw_pcie *pci)
> > if (pci->dwc_pci_quirk & DWC_EQUALIZATION_DISABLE)
> > val |= PORT_LOGIC_GEN3_EQ_DISABLE;
> >
> > + if (pci->dwc_pci_quirk & DWC_EQ_PHASE_2_3_DISABLE)
> > + val |= PORT_LOGIC_GEN3_EQ_PHASE_2_3_DISABLE;
> > +
> > dw_pcie_writel_dbi(pci, PCIE_PORT_GEN3_RELATED, val);
> > }
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > index a1453c5..b541508 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > @@ -31,6 +31,7 @@
> >
> > /* Parameters for PCIe Quirks */
> > #define DWC_EQUALIZATION_DISABLE 0x1
> > +#define DWC_EQ_PHASE_2_3_DISABLE 0x2
>
> It only makes sense for either DWC_EQUALIZATION_DISABLE or DWC_EQ_PHASE_2_3_DISABLE
> to be specified, though if dwc_pci_quirk intends to hold other quirks should these
> be numbers and not bit fields?
>
Yes, you are right in a given platform it will be either
DWC_EQUALIZATION_DISABLE or DWC_EQ_PHASE_2_3_DISABLE.
Intention behind making it bit-field was to add other quirks in future.
> Thanks,
>
> Andrew Murray
>
> >
> > /* Synopsys-specific PCIe configuration registers */
> > #define PCIE_PORT_LINK_CONTROL 0x710
> > @@ -65,6 +66,7 @@
> >
> > #define PCIE_PORT_GEN3_RELATED 0x890
> > #define PORT_LOGIC_GEN3_EQ_DISABLE BIT(16)
> > +#define PORT_LOGIC_GEN3_EQ_PHASE_2_3_DISABLE BIT(9)
> >
> > #define PCIE_ATU_VIEWPORT 0x900
> > #define PCIE_ATU_REGION_INBOUND BIT(31)
> > --
> > 2.7.4
> >
next prev parent reply other threads:[~2019-09-10 16:21 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20190910122514epcas5p4f00c0f999333dd7707c0a353fd06b57f@epcas5p4.samsung.com>
2019-09-10 12:25 ` [PATCH 1/2] PCI: dwc: Add support to disable GEN3 equalization Pankaj Dubey
[not found] ` <CGME20190910122520epcas5p1faeb16f7c38ee057ce93783a637e6bf4@epcas5p1.samsung.com>
2019-09-10 12:25 ` [PATCH 2/2] PCI: dwc: Add support to disable equalization phase 2 and 3 Pankaj Dubey
2019-09-10 14:05 ` Andrew Murray
2019-09-10 16:21 ` Pankaj Dubey [this message]
2019-09-11 9:27 ` Andrew Murray
2019-09-12 11:44 ` Pankaj Dubey
2019-09-10 13:58 ` [PATCH 1/2] PCI: dwc: Add support to disable GEN3 equalization Andrew Murray
2019-09-10 16:16 ` Pankaj Dubey
2019-09-11 9:23 ` Andrew Murray
2019-09-12 11:39 ` Pankaj Dubey
2019-09-12 12:42 ` Andrew Murray
2019-09-12 14:21 ` Gustavo Pimentel
2019-09-13 10:53 ` Pankaj Dubey
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