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 <20210922050035.18162-3-sergio.paracuellos@gmail.com> <20211013130511.GB11036@lpieralisi>
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From:   Sergio Paracuellos <sergio.paracuellos@gmail.com>
Date:   Wed, 13 Oct 2021 15:35:03 +0200
Message-ID: <CAMhs-H8MV+RdL1cgjhBW=wUJm8Nfhe4h4GSC-DH0eLjbtz6wbg@mail.gmail.com>
Subject: Re: [PATCH v3 2/3] PCI: mt7621: Add MediaTek MT7621 PCIe host
 controller driver
To:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc:     linux-pci <linux-pci@vger.kernel.org>,
        John Crispin <john@phrozen.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        "open list:MIPS" <linux-mips@vger.kernel.org>,
        linux-staging@lists.linux.dev, NeilBrown <neil@brown.name>,
        linux-kernel <linux-kernel@vger.kernel.org>
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Precedence: bulk

Hi Lorenzo,

Thanks for the review. See my comments below.

On Wed, Oct 13, 2021 at 3:05 PM Lorenzo Pieralisi
<lorenzo.pieralisi@arm.com> wrote:
>
> On Wed, Sep 22, 2021 at 07:00:34AM +0200, Sergio Paracuellos wrote:
> > Add driver for the PCIe controller of the MT7621 SoC.
> >
> > Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
> > ---
> >  arch/mips/ralink/Kconfig                      |   3 +-
> >  drivers/pci/controller/Kconfig                |   8 ++
> >  drivers/pci/controller/Makefile               |   1 +
> >  .../controller}/pci-mt7621.c                  |   0
> >  drivers/staging/Kconfig                       |   2 -
> >  drivers/staging/Makefile                      |   1 -
> >  drivers/staging/mt7621-pci/Kconfig            |   8 --
> >  drivers/staging/mt7621-pci/Makefile           |   2 -
> >  drivers/staging/mt7621-pci/TODO               |   4 -
> >  .../mt7621-pci/mediatek,mt7621-pci.txt        | 104 ------------------
> >  10 files changed, 11 insertions(+), 122 deletions(-)
> >  rename drivers/{staging/mt7621-pci => pci/controller}/pci-mt7621.c (100%)
> >  delete mode 100644 drivers/staging/mt7621-pci/Kconfig
> >  delete mode 100644 drivers/staging/mt7621-pci/Makefile
> >  delete mode 100644 drivers/staging/mt7621-pci/TODO
> >  delete mode 100644 drivers/staging/mt7621-pci/mediatek,mt7621-pci.txt
> >
> > diff --git a/arch/mips/ralink/Kconfig b/arch/mips/ralink/Kconfig
> > index c800bf5559b5..120adad51d6a 100644
> > --- a/arch/mips/ralink/Kconfig
> > +++ b/arch/mips/ralink/Kconfig
> > @@ -51,7 +51,8 @@ choice
> >               select SYS_SUPPORTS_HIGHMEM
> >               select MIPS_GIC
> >               select CLKSRC_MIPS_GIC
> > -             select HAVE_PCI if PCI_MT7621
> > +             select HAVE_PCI
> > +             select PCI_DRIVERS_GENERIC
> >               select SOC_BUS
> >  endchoice
> >
> > diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
> > index 326f7d13024f..b76404be0360 100644
> > --- a/drivers/pci/controller/Kconfig
> > +++ b/drivers/pci/controller/Kconfig
> > @@ -312,6 +312,14 @@ config PCIE_HISI_ERR
> >         Say Y here if you want error handling support
> >         for the PCIe controller's errors on HiSilicon HIP SoCs
> >
> > +config PCI_MT7621
> > +     tristate "MediaTek MT7621 PCI Controller"
> > +     depends on (RALINK && SOC_MT7621) || (MIPS && COMPILE_TEST)
>
> - Is there a chance we can remove the MIPS dependency from the
>   COMPILE_TEST conditional ?

Driver make use of the following functions to properly configure MIPS
IO coherency regions for used pci addresses:
- 'mips_cps_numiocu()'
- 'write_gcr_reg1_base()'
- 'write_gcr_reg1_mask()'

Without configuring this, the PCI subsystem won't work.
These three are a MIPS thing and we want at the very least to make
COMPILE_TEST available for MIPS. To avoid this I guess we will need
stubs for all the other architectures and I am not really sure it is
really worthly and makes sense.

> - I am not a big fan of "SOC_XXX" config options dependencies, actually
>   there is none in pci/controller. Is there a way to remove it ?

I am not a Kconfig expert, so I am not sure :). This PCI driver needs
only to be available for MIPS RALINK architecture for MT7621 SoCs and
ideally enabled by default for SOC_MT7621. So I don't know if just
doing the following is enough:

config PCI_MT7621
    tristate "MediaTek MT7621 PCI Controller"
    depends on RALINK || (MIPS && COMPILE_TEST)
    select PHY_MT7621_PCI
    default SOC_MT7621
    help
        This selects a driver for the MediaTek MT7621 PCI Controller.

Thanks in advance for clarification.

Best regards,
    Sergio Paracuellos

>
> Lorenzo
>
> > +     select PHY_MT7621_PCI
> > +     default SOC_MT7621
> > +     help
> > +       This selects a driver for the MediaTek MT7621 PCI Controller.
> > +
> >  source "drivers/pci/controller/dwc/Kconfig"
> >  source "drivers/pci/controller/mobiveil/Kconfig"
> >  source "drivers/pci/controller/cadence/Kconfig"
> > diff --git a/drivers/pci/controller/Makefile b/drivers/pci/controller/Makefile
> > index aaf30b3dcc14..f42a566353cb 100644
> > --- a/drivers/pci/controller/Makefile
> > +++ b/drivers/pci/controller/Makefile
> > @@ -37,6 +37,7 @@ obj-$(CONFIG_VMD) += vmd.o
> >  obj-$(CONFIG_PCIE_BRCMSTB) += pcie-brcmstb.o
> >  obj-$(CONFIG_PCI_LOONGSON) += pci-loongson.o
> >  obj-$(CONFIG_PCIE_HISI_ERR) += pcie-hisi-error.o
> > +obj-$(CONFIG_PCI_MT7621) += pci-mt7621.o
> >  # pcie-hisi.o quirks are needed even without CONFIG_PCIE_DW
> >  obj-y                                += dwc/
> >  obj-y                                += mobiveil/
> > diff --git a/drivers/staging/mt7621-pci/pci-mt7621.c b/drivers/pci/controller/pci-mt7621.c
> > similarity index 100%
> > rename from drivers/staging/mt7621-pci/pci-mt7621.c
> > rename to drivers/pci/controller/pci-mt7621.c
> > diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
> > index e03627ad4460..59af251e7576 100644
> > --- a/drivers/staging/Kconfig
> > +++ b/drivers/staging/Kconfig
> > @@ -86,8 +86,6 @@ source "drivers/staging/vc04_services/Kconfig"
> >
> >  source "drivers/staging/pi433/Kconfig"
> >
> > -source "drivers/staging/mt7621-pci/Kconfig"
> > -
> >  source "drivers/staging/mt7621-dma/Kconfig"
> >
> >  source "drivers/staging/ralink-gdma/Kconfig"
> > diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
> > index c7f8d8d8dd11..76f413470bc8 100644
> > --- a/drivers/staging/Makefile
> > +++ b/drivers/staging/Makefile
> > @@ -33,7 +33,6 @@ obj-$(CONFIG_KS7010)                += ks7010/
> >  obj-$(CONFIG_GREYBUS)                += greybus/
> >  obj-$(CONFIG_BCM2835_VCHIQ)  += vc04_services/
> >  obj-$(CONFIG_PI433)          += pi433/
> > -obj-$(CONFIG_PCI_MT7621)     += mt7621-pci/
> >  obj-$(CONFIG_SOC_MT7621)     += mt7621-dma/
> >  obj-$(CONFIG_DMA_RALINK)     += ralink-gdma/
> >  obj-$(CONFIG_SOC_MT7621)     += mt7621-dts/
> > diff --git a/drivers/staging/mt7621-pci/Kconfig b/drivers/staging/mt7621-pci/Kconfig
> > deleted file mode 100644
> > index ce58042f2f21..000000000000
> > --- a/drivers/staging/mt7621-pci/Kconfig
> > +++ /dev/null
> > @@ -1,8 +0,0 @@
> > -# SPDX-License-Identifier: GPL-2.0
> > -config PCI_MT7621
> > -     tristate "MediaTek MT7621 PCI Controller"
> > -     depends on RALINK
> > -     select PCI_DRIVERS_GENERIC
> > -     help
> > -       This selects a driver for the MediaTek MT7621 PCI Controller.
> > -
> > diff --git a/drivers/staging/mt7621-pci/Makefile b/drivers/staging/mt7621-pci/Makefile
> > deleted file mode 100644
> > index f4e651cf7ce3..000000000000
> > --- a/drivers/staging/mt7621-pci/Makefile
> > +++ /dev/null
> > @@ -1,2 +0,0 @@
> > -# SPDX-License-Identifier: GPL-2.0
> > -obj-$(CONFIG_PCI_MT7621)       += pci-mt7621.o
> > diff --git a/drivers/staging/mt7621-pci/TODO b/drivers/staging/mt7621-pci/TODO
> > deleted file mode 100644
> > index d674a9ac85c1..000000000000
> > --- a/drivers/staging/mt7621-pci/TODO
> > +++ /dev/null
> > @@ -1,4 +0,0 @@
> > -
> > -- general code review and cleanup
> > -
> > -Cc: NeilBrown <neil@brown.name>
> > diff --git a/drivers/staging/mt7621-pci/mediatek,mt7621-pci.txt b/drivers/staging/mt7621-pci/mediatek,mt7621-pci.txt
> > deleted file mode 100644
> > index 327a68267309..000000000000
> > --- a/drivers/staging/mt7621-pci/mediatek,mt7621-pci.txt
> > +++ /dev/null
> > @@ -1,104 +0,0 @@
> > -MediaTek MT7621 PCIe controller
> > -
> > -Required properties:
> > -- compatible: "mediatek,mt7621-pci"
> > -- device_type: Must be "pci"
> > -- reg: Base addresses and lengths of the PCIe subsys and root ports.
> > -- bus-range: Range of bus numbers associated with this controller.
> > -- #address-cells: Address representation for root ports (must be 3)
> > -- pinctrl-names : The pin control state names.
> > -- pinctrl-0: The "default" pinctrl state.
> > -- #size-cells: Size representation for root ports (must be 2)
> > -- ranges: Ranges for the PCI memory and I/O regions.
> > -- #interrupt-cells: Must be 1
> > -- interrupt-map-mask and interrupt-map: Standard PCI IRQ mapping properties.
> > -  Please refer to the standard PCI bus binding document for a more detailed
> > -  explanation.
> > -- status: either "disabled" or "okay".
> > -- resets: Must contain an entry for each entry in reset-names.
> > -  See ../reset/reset.txt for details.
> > -- reset-names: Must be "pcie0", "pcie1", "pcieN"... based on the number of
> > -  root ports.
> > -- clocks: Must contain an entry for each entry in clock-names.
> > -  See ../clocks/clock-bindings.txt for details.
> > -- clock-names: Must be "pcie0", "pcie1", "pcieN"... based on the number of
> > -  root ports.
> > -- reset-gpios: GPIO specs for the reset pins.
> > -
> > -In addition, the device tree node must have sub-nodes describing each PCIe port
> > -interface, having the following mandatory properties:
> > -
> > -Required properties:
> > -- reg: Only the first four bytes are used to refer to the correct bus number
> > -      and device number.
> > -- #address-cells: Must be 3
> > -- #size-cells: Must be 2
> > -- ranges: Sub-ranges distributed from the PCIe controller node. An empty
> > -  property is sufficient.
> > -- bus-range: Range of bus numbers associated with this port.
> > -
> > -Example for MT7621:
> > -
> > -     pcie: pcie@1e140000 {
> > -             compatible = "mediatek,mt7621-pci";
> > -        reg = <0x1e140000 0x100    /* host-pci bridge registers */
> > -               0x1e142000 0x100    /* pcie port 0 RC control registers */
> > -               0x1e143000 0x100    /* pcie port 1 RC control registers */
> > -               0x1e144000 0x100>;  /* pcie port 2 RC control registers */
> > -
> > -             #address-cells = <3>;
> > -             #size-cells = <2>;
> > -
> > -             pinctrl-names = "default";
> > -             pinctrl-0 = <&pcie_pins>;
> > -
> > -             device_type = "pci";
> > -
> > -             bus-range = <0 255>;
> > -             ranges = <
> > -                     0x02000000 0 0x00000000 0x60000000 0 0x10000000 /* pci memory */
> > -                     0x01000000 0 0x00000000 0x1e160000 0 0x00010000 /* io space */
> > -             >;
> > -
> > -             #interrupt-cells = <1>;
> > -             interrupt-map-mask = <0xF0000 0 0 1>;
> > -             interrupt-map = <0x10000 0 0 1 &gic GIC_SHARED 4 IRQ_TYPE_LEVEL_HIGH>,
> > -                             <0x20000 0 0 1 &gic GIC_SHARED 24 IRQ_TYPE_LEVEL_HIGH>,
> > -                             <0x30000 0 0 1 &gic GIC_SHARED 25 IRQ_TYPE_LEVEL_HIGH>;
> > -
> > -             status = "disabled";
> > -
> > -             resets = <&rstctrl 24 &rstctrl 25 &rstctrl 26>;
> > -             reset-names = "pcie0", "pcie1", "pcie2";
> > -             clocks = <&clkctrl 24 &clkctrl 25 &clkctrl 26>;
> > -             clock-names = "pcie0", "pcie1", "pcie2";
> > -
> > -             reset-gpios = <&gpio 19 GPIO_ACTIVE_LOW>,
> > -                             <&gpio 8 GPIO_ACTIVE_LOW>,
> > -                             <&gpio 7 GPIO_ACTIVE_LOW>;
> > -
> > -             pcie@0,0 {
> > -                     reg = <0x0000 0 0 0 0>;
> > -                     #address-cells = <3>;
> > -                     #size-cells = <2>;
> > -                     ranges;
> > -                     bus-range = <0x00 0xff>;
> > -             };
> > -
> > -             pcie@1,0 {
> > -                     reg = <0x0800 0 0 0 0>;
> > -                     #address-cells = <3>;
> > -                     #size-cells = <2>;
> > -                     ranges;
> > -                     bus-range = <0x00 0xff>;
> > -             };
> > -
> > -             pcie@2,0 {
> > -                     reg = <0x1000 0 0 0 0>;
> > -                     #address-cells = <3>;
> > -                     #size-cells = <2>;
> > -                     ranges;
> > -                     bus-range = <0x00 0xff>;
> > -             };
> > -     };
> > -
> > --
> > 2.25.1
> >