RE: [RFC 1/2] dt-bindings: imx6q-pcie: Add support for i.MX8QM/QXP PCIe

[Richard Zhu <hongxing.zhu@nxp.com>]

Hi Lucas:
Thanks for your reivew.

> -----Original Message-----
> From: Lucas Stach [mailto:l.stach@pengutronix.de]
> Sent: 2019年3月14日 17:31
> To: Richard Zhu <hongxing.zhu@nxp.com>; bhelgaas@google.com;
> lorenzo.pieralisi@arm.com; andrew.smirnov@gmail.com
> Cc: linux-pci@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linux-kernel@vger.kernel.org
> Subject: Re: [RFC 1/2] dt-bindings: imx6q-pcie: Add support for i.MX8QM/QXP
> PCIe
> 
> Hi Richard,
> 
> Am Mittwoch, den 13.03.2019, 09:15 +0000 schrieb Richard Zhu:
> > Add codes needed to support i.MX8QM/QXP PCIe.
> > - HSIO(High Speed IO) subsystem is new defined on i.MX8QM/QXP.
> >   The PCIe and SATA modules are contained in the HSIO subsystem. There
> >   are two PCIe, one SATA controllers and three mixed lane PHYs on
> >   i.MX8QM. There are three use cases of the HSIO subsystem on
> i.MX8QM.
> >   1. PCIea 2 lanes and one SATA AHCI port.
> >   2. PCIea 1 lane, PCIeb 1 lane and one SATA AHCI port.
> >   3. PCIea 2 lanes, PCIeb 1 lane.
> >   i.MX8QXP only has PCIeb controller and one lane PHY.
> >   Use the hsio-cfg property to specify the different modes.
> > - The HSIO address map as viewed from system level is as shown below.
> >   address [31:24]    Local address    Target    Address Size
> >   5F                 0                HSIO      16
> MB
> >   60-6F              40-4F            HSIO      256MB
> >   70-7F              80-8F            HSIO      256MB
> >   The property local-addr is required to specify it.
> > - Both external OSC and internal PLL can be used as PCIe reference
> >   clock, use the ext_osc property to distinguish them.
> > - clock request GPIO for controlling the PCI reference clock request
> >   signal. And should be configure OD when L1SS maybe enabled later.
> > - One more power domain HSIO_GPIO and clock PCIE_PER are required by
> >   i.MX8QM/QXP PCIe.
> >   Add these specific properties to enable i.MX8QM/QXP PCIe.
> 
> All this HSIO handling should move into a separate PHY driver. This has
> nothing to do with the PCIe controller itself. See for example the Tegra XUSB
> PHY driver (drivers/phy/tegra/xusb.c), which is a similar combined
> PCIE/USB3/SATA PHY driver.
> 
[Richard Zhu] Very good suggestion, would make reference to it and re-orange the codes.
Thanks.

> Regards,
> Lucas
> 
> > Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> > ---
> >  .../devicetree/bindings/pci/fsl,imx6q-pcie.txt      | 21
> > +++++++++++++++++++++
> >  1 file changed, 21 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> > b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> > index a7f5f5a..f7586c9 100644
> > --- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> > +++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> > @@ -10,6 +10,8 @@ Required properties:
> > >  	- "fsl,imx6qp-pcie"
> > >  	- "fsl,imx7d-pcie"
> > >  	- "fsl,imx8mq-pcie"
> > > +	- "fsl,imx8qm-pcie"
> > > +	- "fsl,imx8qxp-pcie"
> >  - reg: base address and length of the PCIe controller
> >  - interrupts: A list of interrupt outputs of the controller. Must
> > contain an
> >    entry for each entry in the interrupt-names property.
> > @@ -38,6 +40,10 @@ Optional properties:
> >    The regulator will be enabled when initializing the PCIe host and
> >    disabled either as part of the init process or when shutting down
> > the
> >    host.
> > +- clkreq-gpio: Should specify the GPIO for controlling the PCI
> > +reference clock
> > +  request signal.
> > +- ext_osc: External OSC is used as PCIe reference clock or not. 0:
> > +Internal
> > +  PLL. 1: External OSC.
> >
> >  Additional required properties for imx6sx-pcie:
> >  - clock names: Must include the following additional entries:
> > @@ -60,6 +66,21 @@ Additional required properties for imx8mq-pcie:
> >  - clock-names: Must include the following additional entries:
> > >  	- "pcie_aux"
> >
> > +Additional required properties for imx8qm/qxp pcie:
> > +- power-domains: Must be set to a phandle pointing to PCIE, PCIE_PHY
> > +power and
> > +  HSIO_GPIO domains
> > +- power-domain-names: Must be "pcie", "pcie_phy", "hsio_gpio"
> > +- clock-names: Must include the following additional entries:
> > > +	- "pcie_per"
> > +- hsio-cfg: hsio configration mode when the pcie node is supported.
> > +  1: pciea 2 lanes and one sata ahci port.
> > +  2: pciea 1 lane, pcieb 1 lane and one sata ahci port.
> > +  3: pciea 2 lanes, pcieb 1 lane.
> > +- local-addr: the local address used in hsio module on i.MX8QM/QXP.
> > > +	Example:
> > > +		hsio-cfg = <2>;
> > > +		local-addr = <0x80000000>;
> > +
> >  Example:
> >
> > >  	pcie@01000000 {