RE: [PATCH 2/2] PCI: dwc: Add support to handle ZRX-DC Compliant PHYs

["Pankaj Dubey" <pankaj.dubey@samsung.com>]

> -----Original Message-----
> From: Andrew Murray <andrew.murray@arm.com>
> Sent: Monday, October 21, 2019 7:34 PM
> To: Anvesh Salveru <anvesh.s@samsung.com>
> Cc: linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org;
> bhelgaas@google.com; gustavo.pimentel@synopsys.com;
> jingoohan1@gmail.com; lorenzo.pieralisi@arm.com; Pankaj Dubey
> <pankaj.dubey@samsung.com>
> Subject: Re: [PATCH 2/2] PCI: dwc: Add support to handle ZRX-DC Compliant
> PHYs
> 
> On Mon, Oct 21, 2019 at 05:59:53PM +0530, Anvesh Salveru wrote:
> > Many platforms use DesignWare controller but the PHY can be different
> > in different platforms. If the PHY is compliant is to ZRX-DC
> > specification
> 
> s/is to/to the/

OK

> 
> > it helps in low power consumption during power states.
> 
> s/in low/lower/
> 
OK
> >
> > If current data rate is 8.0 GT/s or higher and PHY is not compliant to
> > ZRX-DC specification, then after every 100ms link should transition to
> > recovery state during the low power states.
> >
> > DesignWare controller provides GEN3_ZRXDC_NONCOMPL field in
> > GEN3_RELATED_OFF to specify about ZRX-DC compliant PHY.
> >
> > Platforms with ZRX-DC compliant PHY can set "snps,phy-zrxdc-compliant"
> > property in controller DT node to specify this property to the
controller.
> >
> > 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 | 7 +++++++
> > drivers/pci/controller/dwc/pcie-designware.h | 3 +++
> >  2 files changed, 10 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c
> > b/drivers/pci/controller/dwc/pcie-designware.c
> > index 820488dfeaed..6560d9f765d7 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -556,4 +556,11 @@ void dw_pcie_setup(struct dw_pcie *pci)
> >  		       PCIE_PL_CHK_REG_CHK_REG_START;
> >  		dw_pcie_writel_dbi(pci, PCIE_PL_CHK_REG_CONTROL_STATUS,
> val);
> >  	}
> > +
> > +	if (of_property_read_bool(np, "snps,phy-zrxdc-compliant")) {
> > +		val = dw_pcie_readl_dbi(pci, PCIE_PORT_GEN3_RELATED);
> > +		val &= ~PORT_LOGIC_GEN3_ZRXDC_NONCOMPL;
> > +		dw_pcie_writel_dbi(pci, PCIE_PORT_GEN3_RELATED, val);
> > +	}
> > +
> 
> Given that this duplicates tegra_pcie_prepare_host in pcie-tegra194.c, can
we
> update that driver to adopt this new binding?
> 

Yes, Thanks for highlighting this. Otherwise I was worried that we have one
more patch without real user :)
We will update pcie-tegra194.c driver and post the patch to adopt this
binding.

> Thanks,
> 
> Andrew Murray
> 
> >  }
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.h
> > b/drivers/pci/controller/dwc/pcie-designware.h
> > index 5a18e94e52c8..427a55ec43c6 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > @@ -60,6 +60,9 @@
> >  #define PCIE_MSI_INTR0_MASK		0x82C
> >  #define PCIE_MSI_INTR0_STATUS		0x830
> >
> > +#define PCIE_PORT_GEN3_RELATED		0x890
> > +#define PORT_LOGIC_GEN3_ZRXDC_NONCOMPL		BIT(0)
> > +
> >  #define PCIE_ATU_VIEWPORT		0x900
> >  #define PCIE_ATU_REGION_INBOUND		BIT(31)
> >  #define PCIE_ATU_REGION_OUTBOUND	0
> > --
> > 2.17.1
> >