All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Magnus Damm <magnus.damm@gmail.com>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	Marek Vasut <marek.vasut+renesas@gmail.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	linux-pci <linux-pci@vger.kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Murray <andrew.murray@arm.com>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	Chris Paterson <Chris.Paterson2@renesas.com>,
	"Lad, Prabhakar" <prabhakar.mahadev-lad.rj@bp.renesas.com>
Subject: Re: [PATCH 3/5] PCI: rcar: Add R-Car PCIe endpoint device tree bindings
Date: Thu, 7 Nov 2019 22:46:28 +0000	[thread overview]
Message-ID: <CA+V-a8sS4gX8o__R_pHK2Otb=s_aAWbtvDLfOhAQAJb77Jz_Sw@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdXkbWkQgswMNL7Dw7_jucH+MsuAW+-CjoGVYsm=tjShRw@mail.gmail.com>

Hi Geert,

On Thu, Nov 7, 2019 at 8:08 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Thu, Nov 7, 2019 at 10:26 AM Lad, Prabhakar
> <prabhakar.csengg@gmail.com> wrote:
> > On Thu, Nov 7, 2019 at 8:44 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > On Wed, Nov 6, 2019 at 8:36 PM Lad Prabhakar <prabhakar.csengg@gmail.com> wrote:
> > > > From: "Lad, Prabhakar" <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > > >
> > > > This patch adds the bindings for the R-Car PCIe endpoint driver.
> > > >
> > > > Signed-off-by: Lad, Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > >
> > > Thanks for your patch!
> > >
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/pci/rcar-pci-ep.txt
> > > > @@ -0,0 +1,43 @@
> > > > +* Renesas R-Car PCIe Endpoint Controller DT description
> > > > +
> > > > +Required properties:
> > > > +           "renesas,pcie-ep-r8a774c0" for the R8A774C0 SoC;
> > > > +           "renesas,pcie-ep-rcar-gen3" for a generic R-Car Gen3 or
> > > > +                                    RZ/G2 compatible device.
> > >
> > > Unless I'm missing something, this is for the exact same hardware block as
> > > Documentation/devicetree/bindings/pci/rcar-pci.txt?
> > > So shouldn't you amend those bindings, instead of adding new compatible
> > > values?
> > > Please remember that DT describes hardware, not software policy.
> > > So IMHO choosing between host and endpoint is purely a configuration
> > > issue, and could be indicated by the presence or lack of some DT properties.
> > > E.g. host mode requires both "bus-range" and "device_type" properties,
> > > so their absence could indicate endpoint mode.
> > >
> > yes its the same hardware block as described in the rcar-pci.txt, I
> > did think about amending it
> > but  it might turn out to be bit messy,
> >
> > required properties host ======required properties Endpoint
> > ====================||==================
> > 1: reg                                || reg
> > 2:bus-range                      || reg names
> > 3: device_type                  || resets
> > 4: ranges                          || clocks
> > 5: dma-ranges                  || clock-names
> > 6: interrupts                      ||
> > 7: interrupt-cells               ||
> > 8: interrupt-map-mask     ||
> > 9: clocks                          ||
> > 10: clock-names             ||
>
> We have a similar situation with SPI, where a controller can operate in
> master or slave mode, based on the absence or presence of the
> "spi-slave" DT property.
>
> > and if I go ahead with the same compatible string that would mean to
> > add support for endpoint
> > mode in the host driver itself. I did follow the examples of
>
> You can still have two separate drivers, binding against the same
> compatible value.  Just let the .probe() function return -ENODEV if it
> discovers (by looking at DT properties) if the node is configured for
> the other mode.
> Which brings us to my next questions: is there any code that could be
> shared between the drivers for the two modes?
>
agreed driver probe could handle depending on the DT properties.
yes there is bit of common code and the first patch of the series prepares
for handling host and endpoint mode.

> > rockchip/cadence/designware where
> > its the same hardware block but has two different binding files one
> > for host mode and other for
> > endpoint mode.
>
> Having two separate DT binding documents sounds fine to me, if unifying
> them makes things too complex.
> However, I think they should use the same compatible value, because the
> hardware block is the same, but just used in a different mode.
>
agreed.

> Rob/Mark: Any input from the DT maintainers?
>
> > > > +- reg: Five register ranges as listed in the reg-names property
> > > > +- reg-names: Must include the following names
> > > > +       - "apb-base"
> > > > +       - "memory0"
> > > > +       - "memory1"
> > > > +       - "memory2"
> > > > +       - "memory3"
> > >
> > > What is the purpose of the last 4 regions?
> > > Can they be chosen by the driver, at runtime?
> > >
> > no the driver cannot choose them at runtime, as these are the only
> > PCIE memory(0/1/2/3) ranges
> > in the AXI address space where host memory can be mapped.
>
> Are they fixed by the PCIe hardware, i.e. could they be looked up by the
> driver based on the compatible value?
>
yes they are fixed by the PCIe hardware and could be looked up by the driver
based on the compatible value.

Cheers,
--Prabhakar

WARNING: multiple messages have this Message-ID
From: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	Chris Paterson <Chris.Paterson2@renesas.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	"Lad, Prabhakar" <prabhakar.mahadev-lad.rj@bp.renesas.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-pci <linux-pci@vger.kernel.org>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	Magnus Damm <magnus.damm@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Andrew Murray <andrew.murray@arm.com>,
	Will Deacon <will@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Marek Vasut <marek.vasut+renesas@gmail.com>
Subject: Re: [PATCH 3/5] PCI: rcar: Add R-Car PCIe endpoint device tree bindings
Date: Thu, 7 Nov 2019 22:46:28 +0000	[thread overview]
Message-ID: <CA+V-a8sS4gX8o__R_pHK2Otb=s_aAWbtvDLfOhAQAJb77Jz_Sw@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdXkbWkQgswMNL7Dw7_jucH+MsuAW+-CjoGVYsm=tjShRw@mail.gmail.com>

Hi Geert,

On Thu, Nov 7, 2019 at 8:08 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Thu, Nov 7, 2019 at 10:26 AM Lad, Prabhakar
> <prabhakar.csengg@gmail.com> wrote:
> > On Thu, Nov 7, 2019 at 8:44 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > On Wed, Nov 6, 2019 at 8:36 PM Lad Prabhakar <prabhakar.csengg@gmail.com> wrote:
> > > > From: "Lad, Prabhakar" <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > > >
> > > > This patch adds the bindings for the R-Car PCIe endpoint driver.
> > > >
> > > > Signed-off-by: Lad, Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > >
> > > Thanks for your patch!
> > >
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/pci/rcar-pci-ep.txt
> > > > @@ -0,0 +1,43 @@
> > > > +* Renesas R-Car PCIe Endpoint Controller DT description
> > > > +
> > > > +Required properties:
> > > > +           "renesas,pcie-ep-r8a774c0" for the R8A774C0 SoC;
> > > > +           "renesas,pcie-ep-rcar-gen3" for a generic R-Car Gen3 or
> > > > +                                    RZ/G2 compatible device.
> > >
> > > Unless I'm missing something, this is for the exact same hardware block as
> > > Documentation/devicetree/bindings/pci/rcar-pci.txt?
> > > So shouldn't you amend those bindings, instead of adding new compatible
> > > values?
> > > Please remember that DT describes hardware, not software policy.
> > > So IMHO choosing between host and endpoint is purely a configuration
> > > issue, and could be indicated by the presence or lack of some DT properties.
> > > E.g. host mode requires both "bus-range" and "device_type" properties,
> > > so their absence could indicate endpoint mode.
> > >
> > yes its the same hardware block as described in the rcar-pci.txt, I
> > did think about amending it
> > but  it might turn out to be bit messy,
> >
> > required properties host ======required properties Endpoint
> > ====================||==================
> > 1: reg                                || reg
> > 2:bus-range                      || reg names
> > 3: device_type                  || resets
> > 4: ranges                          || clocks
> > 5: dma-ranges                  || clock-names
> > 6: interrupts                      ||
> > 7: interrupt-cells               ||
> > 8: interrupt-map-mask     ||
> > 9: clocks                          ||
> > 10: clock-names             ||
>
> We have a similar situation with SPI, where a controller can operate in
> master or slave mode, based on the absence or presence of the
> "spi-slave" DT property.
>
> > and if I go ahead with the same compatible string that would mean to
> > add support for endpoint
> > mode in the host driver itself. I did follow the examples of
>
> You can still have two separate drivers, binding against the same
> compatible value.  Just let the .probe() function return -ENODEV if it
> discovers (by looking at DT properties) if the node is configured for
> the other mode.
> Which brings us to my next questions: is there any code that could be
> shared between the drivers for the two modes?
>
agreed driver probe could handle depending on the DT properties.
yes there is bit of common code and the first patch of the series prepares
for handling host and endpoint mode.

> > rockchip/cadence/designware where
> > its the same hardware block but has two different binding files one
> > for host mode and other for
> > endpoint mode.
>
> Having two separate DT binding documents sounds fine to me, if unifying
> them makes things too complex.
> However, I think they should use the same compatible value, because the
> hardware block is the same, but just used in a different mode.
>
agreed.

> Rob/Mark: Any input from the DT maintainers?
>
> > > > +- reg: Five register ranges as listed in the reg-names property
> > > > +- reg-names: Must include the following names
> > > > +       - "apb-base"
> > > > +       - "memory0"
> > > > +       - "memory1"
> > > > +       - "memory2"
> > > > +       - "memory3"
> > >
> > > What is the purpose of the last 4 regions?
> > > Can they be chosen by the driver, at runtime?
> > >
> > no the driver cannot choose them at runtime, as these are the only
> > PCIE memory(0/1/2/3) ranges
> > in the AXI address space where host memory can be mapped.
>
> Are they fixed by the PCIe hardware, i.e. could they be looked up by the
> driver based on the compatible value?
>
yes they are fixed by the PCIe hardware and could be looked up by the driver
based on the compatible value.

Cheers,
--Prabhakar

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2019-11-07 22:46 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06 19:36 [PATCH 0/5] Add support for PCIe controller to work in endpoint mode on R-Car SoCs Lad Prabhakar
2019-11-06 19:36 ` Lad Prabhakar
2019-11-06 19:36 ` [PATCH 1/5] pci: pcie-rcar: preparation for adding endpoint support Lad Prabhakar
2019-11-06 19:36   ` Lad Prabhakar
2019-11-27  4:55   ` Kishon Vijay Abraham I
2019-11-27  4:55     ` Kishon Vijay Abraham I
2019-11-27 20:51     ` Lad, Prabhakar
2019-11-27 20:51       ` Lad, Prabhakar
2019-11-06 19:36 ` [PATCH 2/5] pci: endpoint: add support to handle multiple base for mapping outbound memory Lad Prabhakar
2019-11-06 19:36   ` Lad Prabhakar
2019-11-27  5:14   ` Kishon Vijay Abraham I
2019-11-27  5:14     ` Kishon Vijay Abraham I
2019-11-27  5:14     ` Kishon Vijay Abraham I
2019-11-27 21:21     ` Lad, Prabhakar
2019-11-27 21:21       ` Lad, Prabhakar
2019-11-27 21:21       ` Lad, Prabhakar
2019-12-05 10:22       ` Kishon Vijay Abraham I
2019-12-05 10:22         ` Kishon Vijay Abraham I
2019-12-05 10:22         ` Kishon Vijay Abraham I
2019-12-06 13:08         ` Lad, Prabhakar
2019-12-06 13:08           ` Lad, Prabhakar
2019-12-06 13:08           ` Lad, Prabhakar
2019-11-27  6:05   ` Kishon Vijay Abraham I
2019-11-27  6:05     ` Kishon Vijay Abraham I
2019-11-27  6:05     ` Kishon Vijay Abraham I
2019-11-27 21:28     ` Lad, Prabhakar
2019-11-27 21:28       ` Lad, Prabhakar
2019-11-27 21:28       ` Lad, Prabhakar
2019-11-06 19:36 ` [PATCH 3/5] PCI: rcar: Add R-Car PCIe endpoint device tree bindings Lad Prabhakar
2019-11-06 19:36   ` Lad Prabhakar
2019-11-07  7:39   ` Biju Das
2019-11-07  7:39     ` Biju Das
2019-11-07  8:10     ` Lad, Prabhakar
2019-11-07  8:10       ` Lad, Prabhakar
2019-11-07  8:44   ` Geert Uytterhoeven
2019-11-07  8:44     ` Geert Uytterhoeven
2019-11-07  9:25     ` Lad, Prabhakar
2019-11-07  9:25       ` Lad, Prabhakar
2019-11-07 20:08       ` Geert Uytterhoeven
2019-11-07 20:08         ` Geert Uytterhoeven
2019-11-07 22:46         ` Lad, Prabhakar [this message]
2019-11-07 22:46           ` Lad, Prabhakar
2019-11-08  8:36           ` Geert Uytterhoeven
2019-11-08  8:36             ` Geert Uytterhoeven
2019-11-13  4:08         ` Rob Herring
2019-11-13  4:08           ` Rob Herring
2019-11-27  5:44           ` Kishon Vijay Abraham I
2019-11-27  5:44             ` Kishon Vijay Abraham I
2019-11-27 21:00             ` Lad, Prabhakar
2019-11-27 21:00               ` Lad, Prabhakar
2019-11-06 19:36 ` [PATCH 4/5] pci: rcar: add support for rcar pcie controller in endpoint mode Lad Prabhakar
2019-11-06 19:36   ` Lad Prabhakar
2019-11-06 19:36 ` [PATCH 5/5] misc: pci_endpoint_test: add device-id for RZ/G2 pcie controller Lad Prabhakar
2019-11-06 19:36   ` Lad Prabhakar
2019-11-27  5:45   ` Kishon Vijay Abraham I
2019-11-27  5:45     ` Kishon Vijay Abraham I
2019-11-26 14:33 ` [PATCH 0/5] Add support for PCIe controller to work in endpoint mode on R-Car SoCs Lad, Prabhakar
2019-11-26 14:33   ` Lad, Prabhakar
2019-11-27  6:07   ` Kishon Vijay Abraham I
2019-11-27  6:07     ` Kishon Vijay Abraham I

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CA+V-a8sS4gX8o__R_pHK2Otb=s_aAWbtvDLfOhAQAJb77Jz_Sw@mail.gmail.com' \
    --to=prabhakar.csengg@gmail.com \
    --cc=Chris.Paterson2@renesas.com \
    --cc=andrew.murray@arm.com \
    --cc=arnd@arndb.de \
    --cc=bhelgaas@google.com \
    --cc=catalin.marinas@arm.com \
    --cc=devicetree@vger.kernel.org \
    --cc=geert@linux-m68k.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=kishon@ti.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=linux-renesas-soc@vger.kernel.org \
    --cc=lorenzo.pieralisi@arm.com \
    --cc=magnus.damm@gmail.com \
    --cc=marek.vasut+renesas@gmail.com \
    --cc=mark.rutland@arm.com \
    --cc=prabhakar.mahadev-lad.rj@bp.renesas.com \
    --cc=robh+dt@kernel.org \
    --cc=will@kernel.org \
    --cc=yoshihiro.shimoda.uh@renesas.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.