[PATCH v3 0/9] Raspberry Pi 4 USB firmware initialization rework

[PATCH v3 0/9] Raspberry Pi 4 USB firmware initialization rework

[Nicolas Saenz Julienne]

On the Raspberry Pi 4, after a PCI reset, VL805's firmware may either be
loaded directly from an EEPROM or, if not present, by the SoC's
co-processor, VideoCore. This series reworks how we handle this.

The previous solution makes use of PCI quirks and exporting platform
specific functions. Albeit functional it feels pretty shoehorned. This
proposes an alternative way of handling the triggering of the xHCI chip
initialization trough means of a reset controller.

The benefits are pretty evident: less platform churn in core xHCI code,
and no explicit device dependency management in pcie-brcmstb.

Note that patch #1 depends on another series[1].

The series is based on next-20200611

v2: https://lkml.org/lkml/2020/6/9/875
v1: https://lore.kernel.org/linux-usb/20200608192701.18355-1-nsaenzjulienne@suse.de/T/#t

[1] https://lwn.net/ml/linux-kernel/cover.662a8d401787ef33780d91252a352de91dc4be10.1590594293.git-series.maxime@cerno.tech/

---

Changes since v2:
 - Add reset to resume routine in xhci-pci
 - Correct of refcount in pci-quirks
 - Correct typos
 - Use include file to define firmware reset IDs

Changes since v1:
 - Rework reset controller so it's less USB centric.
 - Use correct reset controller API in xhci-pci
 - Correct typos

Nicolas Saenz Julienne (9):
  dt-bindings: reset: Add a binding for the RPi Firmware reset
    controller
  reset: Add Raspberry Pi 4 firmware reset controller
  ARM: dts: bcm2711: Add firmware usb reset node
  ARM: dts: bcm2711: Add reset controller to xHCI node
  usb: xhci-pci: Add support for reset controllers
  Revert "USB: pci-quirks: Add Raspberry Pi 4 quirk"
  usb: host: pci-quirks: Bypass xHCI quirks for Raspberry Pi 4
  Revert "firmware: raspberrypi: Introduce vl805 init routine"
  Revert "PCI: brcmstb: Wait for Raspberry Pi's firmware when present"

 .../arm/bcm/raspberrypi,bcm2835-firmware.yaml |  21 +++
 arch/arm/boot/dts/bcm2711-rpi-4-b.dts         |  14 ++
 drivers/firmware/Kconfig                      |   3 +-
 drivers/firmware/raspberrypi.c                |  61 ---------
 drivers/pci/controller/pcie-brcmstb.c         |  17 ---
 drivers/reset/Kconfig                         |  11 ++
 drivers/reset/Makefile                        |   1 +
 drivers/reset/reset-raspberrypi.c             | 122 ++++++++++++++++++
 drivers/usb/host/pci-quirks.c                 |  22 ++--
 drivers/usb/host/xhci-pci.c                   |  10 ++
 drivers/usb/host/xhci.h                       |   2 +
 .../reset/raspberrypi,firmware-reset.h        |  13 ++
 include/soc/bcm2835/raspberrypi-firmware.h    |   7 -
 13 files changed, 207 insertions(+), 97 deletions(-)
 create mode 100644 drivers/reset/reset-raspberrypi.c
 create mode 100644 include/dt-bindings/reset/raspberrypi,firmware-reset.h

-- 
2.26.2

[PATCH v3 1/9] dt-bindings: reset: Add a binding for the RPi Firmware reset controller

[Nicolas Saenz Julienne]

The firmware running on the RPi VideoCore can be used to reset and
initialize HW controlled by the firmware.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

---
Changes since v2:
 - Add include file for reset IDs

Changes since v1:
 - Correct cells binding as per Florian's comment
 - Change compatible string to be more generic

 .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 21 +++++++++++++++++++
 .../reset/raspberrypi,firmware-reset.h        | 13 ++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 include/dt-bindings/reset/raspberrypi,firmware-reset.h

diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
index b48ed875eb8e..23a885af3a28 100644
--- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
+++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
@@ -39,6 +39,22 @@ properties:
       - compatible
       - "#clock-cells"
 
+  reset:
+    type: object
+
+    properties:
+      compatible:
+        const: raspberrypi,firmware-reset
+
+      "#reset-cells":
+        const: 1
+        description: >
+          The argument is the ID of the firmware reset line to affect.
+
+    required:
+      - compatible
+      - "#reset-cells"
+
     additionalProperties: false
 
 required:
@@ -55,5 +71,10 @@ examples:
             compatible = "raspberrypi,firmware-clocks";
             #clock-cells = <1>;
         };
+
+        reset: reset {
+            compatible = "raspberrypi,firmware-reset";
+            #reset-cells = <1>;
+        };
     };
 ...
diff --git a/include/dt-bindings/reset/raspberrypi,firmware-reset.h b/include/dt-bindings/reset/raspberrypi,firmware-reset.h
new file mode 100644
index 000000000000..1a4f4c792723
--- /dev/null
+++ b/include/dt-bindings/reset/raspberrypi,firmware-reset.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2020 Nicolas Saenz Julienne
+ * Author: Nicolas Saenz Julienne <nsaenzjulienne@suse.com>
+ */
+
+#ifndef _DT_BINDINGS_RASPBERRYPI_FIRMWARE_RESET_H
+#define _DT_BINDINGS_RASPBERRYPI_FIRMWARE_RESET_H
+
+#define RASPBERRYPI_FIRMWARE_RESET_ID_USB	0
+#define RASPBERRYPI_FIRMWARE_RESET_NUM_IDS	1
+
+#endif
-- 
2.26.2

[PATCH v3 3/9] ARM: dts: bcm2711: Add firmware usb reset node

[Nicolas Saenz Julienne]

Now that the reset driver exposing Raspberry Pi 4's firmware based USB
reset routine is available, let's add the device tree node exposing it.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

---

Changes since v1:
 - Update cell nr to match new bindings

 arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
index c7f1d97e69bb..0cef95058fb0 100644
--- a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
+++ b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
@@ -83,6 +83,11 @@ expgpio: gpio {
 				  "";
 		status = "okay";
 	};
+
+	reset: reset {
+		compatible = "raspberrypi,firmware-reset";
+		#reset-cells = <1>;
+	};
 };
 
 &gpio {
-- 
2.26.2

[PATCH v3 4/9] ARM: dts: bcm2711: Add reset controller to xHCI node

[Nicolas Saenz Julienne]

The chip is hardwired to the board's PCIe bus and needs to be properly
setup trough a firmware routine after a PCI fundamental reset. Pass the
reset controller phandle that takes care of triggering the
initialization to the relevant PCI device.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

---

Changes since v2:
 - Use dt-bindings to access IDs

Changes since v1:
 - Update to match new binding

 arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
index 0cef95058fb0..e20979013414 100644
--- a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
+++ b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
@@ -4,6 +4,8 @@
 #include "bcm2835-rpi.dtsi"
 #include "bcm283x-rpi-usb-peripheral.dtsi"
 
+#include <dt-bindings/reset/raspberrypi,firmware-reset.h>
+
 / {
 	compatible = "raspberrypi,4-model-b", "brcm,bcm2711";
 	model = "Raspberry Pi 4 Model B";
@@ -207,6 +209,13 @@ phy1: ethernet-phy@1 {
 	};
 };
 
+&pcie0 {
+	usb@1,0 {
+		reg = <0 0 0 0 0>;
+		resets = <&reset RASPBERRYPI_FIRMWARE_RESET_ID_USB>;
+	};
+};
+
 /* uart0 communicates with the BT module */
 &uart0 {
 	pinctrl-names = "default";
-- 
2.26.2

Re: [PATCH v3 1/9] dt-bindings: reset: Add a binding for the RPi Firmware reset controller

[Philipp Zabel]

Hi Nicolas,

On Fri, 2020-06-12 at 19:13 +0200, Nicolas Saenz Julienne wrote:
> The firmware running on the RPi VideoCore can be used to reset and
> initialize HW controlled by the firmware.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
> 
> ---
> Changes since v2:
>  - Add include file for reset IDs
> 
> Changes since v1:
>  - Correct cells binding as per Florian's comment
>  - Change compatible string to be more generic
> 
>  .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 21 +++++++++++++++++++
>  .../reset/raspberrypi,firmware-reset.h        | 13 ++++++++++++
>  2 files changed, 34 insertions(+)
>  create mode 100644 include/dt-bindings/reset/raspberrypi,firmware-reset.h
> 
> diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
> index b48ed875eb8e..23a885af3a28 100644
> --- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
> +++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
> @@ -39,6 +39,22 @@ properties:
>        - compatible
>        - "#clock-cells"
>  
> +  reset:
> +    type: object
> +
> +    properties:
> +      compatible:
> +        const: raspberrypi,firmware-reset
> +
> +      "#reset-cells":
> +        const: 1
> +        description: >
> +          The argument is the ID of the firmware reset line to affect.
> +
> +    required:
> +      - compatible
> +      - "#reset-cells"
> +
>      additionalProperties: false
>  
>  required:
> @@ -55,5 +71,10 @@ examples:
>              compatible = "raspberrypi,firmware-clocks";
>              #clock-cells = <1>;
>          };
> +
> +        reset: reset {
> +            compatible = "raspberrypi,firmware-reset";
> +            #reset-cells = <1>;
> +        };
>      };
>  ...
> diff --git a/include/dt-bindings/reset/raspberrypi,firmware-reset.h b/include/dt-bindings/reset/raspberrypi,firmware-reset.h
> new file mode 100644
> index 000000000000..1a4f4c792723
> --- /dev/null
> +++ b/include/dt-bindings/reset/raspberrypi,firmware-reset.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2020 Nicolas Saenz Julienne
> + * Author: Nicolas Saenz Julienne <nsaenzjulienne@suse.com>
> + */
> +
> +#ifndef _DT_BINDINGS_RASPBERRYPI_FIRMWARE_RESET_H
> +#define _DT_BINDINGS_RASPBERRYPI_FIRMWARE_RESET_H
> +
> +#define RASPBERRYPI_FIRMWARE_RESET_ID_USB	0
> +#define RASPBERRYPI_FIRMWARE_RESET_NUM_IDS	1
> +
> +#endif

Are there going to be any more firmware controlled resets in the future?

regards
Philipp

Re: [PATCH v3 1/9] dt-bindings: reset: Add a binding for the RPi Firmware reset controller

[Nicolas Saenz Julienne]

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Hi,

On Wed, 2020-06-17 at 11:55 +0200, Philipp Zabel wrote:
> Hi Nicolas,
> 
> On Fri, 2020-06-12 at 19:13 +0200, Nicolas Saenz Julienne wrote:
> > The firmware running on the RPi VideoCore can be used to reset and
> > initialize HW controlled by the firmware.
> > 
> > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> > Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
> > 
> > ---
> > Changes since v2:
> >  - Add include file for reset IDs
> > 
> > Changes since v1:
> >  - Correct cells binding as per Florian's comment
> >  - Change compatible string to be more generic
> > 
> >  .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 21 +++++++++++++++++++
> >  .../reset/raspberrypi,firmware-reset.h        | 13 ++++++++++++
> >  2 files changed, 34 insertions(+)
> >  create mode 100644 include/dt-bindings/reset/raspberrypi,firmware-reset.h
> > 
> > diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > firmware.yaml
> > b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > firmware.yaml
> > index b48ed875eb8e..23a885af3a28 100644
> > --- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > firmware.yaml
> > +++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > firmware.yaml
> > @@ -39,6 +39,22 @@ properties:
> >        - compatible
> >        - "#clock-cells"
> >  
> > +  reset:
> > +    type: object
> > +
> > +    properties:
> > +      compatible:
> > +        const: raspberrypi,firmware-reset
> > +
> > +      "#reset-cells":
> > +        const: 1
> > +        description: >
> > +          The argument is the ID of the firmware reset line to affect.
> > +
> > +    required:
> > +      - compatible
> > +      - "#reset-cells"
> > +
> >      additionalProperties: false
> >  
> >  required:
> > @@ -55,5 +71,10 @@ examples:
> >              compatible = "raspberrypi,firmware-clocks";
> >              #clock-cells = <1>;
> >          };
> > +
> > +        reset: reset {
> > +            compatible = "raspberrypi,firmware-reset";
> > +            #reset-cells = <1>;
> > +        };
> >      };
> >  ...
> > diff --git a/include/dt-bindings/reset/raspberrypi,firmware-reset.h
> > b/include/dt-bindings/reset/raspberrypi,firmware-reset.h
> > new file mode 100644
> > index 000000000000..1a4f4c792723
> > --- /dev/null
> > +++ b/include/dt-bindings/reset/raspberrypi,firmware-reset.h
> > @@ -0,0 +1,13 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Copyright (c) 2020 Nicolas Saenz Julienne
> > + * Author: Nicolas Saenz Julienne <nsaenzjulienne@suse.com>
> > + */
> > +
> > +#ifndef _DT_BINDINGS_RASPBERRYPI_FIRMWARE_RESET_H
> > +#define _DT_BINDINGS_RASPBERRYPI_FIRMWARE_RESET_H
> > +
> > +#define RASPBERRYPI_FIRMWARE_RESET_ID_USB	0
> > +#define RASPBERRYPI_FIRMWARE_RESET_NUM_IDS	1
> > +
> > +#endif
> 
> Are there going to be any more firmware controlled resets in the future?

There are not right now, but it's likely some will show up in the future. I
have some contenders in mind, which I'll request once we settle on a design
here, but it ultimately depends on what the RPi people decide to implement.

Regards,
Nicolas


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Re: [PATCH v3 4/9] ARM: dts: bcm2711: Add reset controller to xHCI node

[Nicolas Saenz Julienne]

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Hi All,

On Fri, 2020-06-12 at 19:13 +0200, Nicolas Saenz Julienne wrote:
> The chip is hardwired to the board's PCIe bus and needs to be properly
> setup trough a firmware routine after a PCI fundamental reset. Pass the
> reset controller phandle that takes care of triggering the
> initialization to the relevant PCI device.
>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
>
> ---
>
> Changes since v2:
>  - Use dt-bindings to access IDs
>
> Changes since v1:
>  - Update to match new binding
>
>  arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> index 0cef95058fb0..e20979013414 100644
> --- a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> +++ b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
> @@ -4,6 +4,8 @@
>  #include "bcm2835-rpi.dtsi"
>  #include "bcm283x-rpi-usb-peripheral.dtsi"
>
> +#include <dt-bindings/reset/raspberrypi,firmware-reset.h>
> +
>  / {
>  	compatible = "raspberrypi,4-model-b", "brcm,bcm2711";
>  	model = "Raspberry Pi 4 Model B";
> @@ -207,6 +209,13 @@ phy1: ethernet-phy@1 {
>  	};
>  };
>
> +&pcie0 {
> +	usb@1,0 {
> +		reg = <0 0 0 0 0>;
> +		resets = <&reset RASPBERRYPI_FIRMWARE_RESET_ID_USB>;
> +	};
> +};
> +

I'm now double-guessing this is correct. With this lspci -tv output:

[0000:00]---00.0-[01]----00.0  VIA Technologies, Inc. VL805 USB 3.0 Host Controller

The DT patch should be more like this:

+&pcie0 {
+       pci@0 {
+               #address-cells = <3>;
+               #size-cells = <2>;
+               ranges;
+
+               reg = <0 0 0 0 0>;
+
+               usb@1,0 {
+                       reg = <0x10000 0 0 0 0>;
+                       resets = <&reset RASPBERRYPI_FIRMWARE_RESET_ID_USB>;
+               };
+       };
+};

Small details aside I'm pretty confident this is the way to go, but would
appreciate some comments/validation.

Regards,
Nicolas


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Re: [PATCH v3 1/9] dt-bindings: reset: Add a binding for the RPi Firmware reset controller

[Rob Herring]

On Fri, Jun 12, 2020 at 07:13:25PM +0200, Nicolas Saenz Julienne wrote:
> The firmware running on the RPi VideoCore can be used to reset and
> initialize HW controlled by the firmware.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
> 
> ---
> Changes since v2:
>  - Add include file for reset IDs
> 
> Changes since v1:
>  - Correct cells binding as per Florian's comment
>  - Change compatible string to be more generic
> 
>  .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 21 +++++++++++++++++++
>  .../reset/raspberrypi,firmware-reset.h        | 13 ++++++++++++
>  2 files changed, 34 insertions(+)
>  create mode 100644 include/dt-bindings/reset/raspberrypi,firmware-reset.h
> 
> diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
> index b48ed875eb8e..23a885af3a28 100644
> --- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
> +++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
> @@ -39,6 +39,22 @@ properties:
>        - compatible
>        - "#clock-cells"
>  
> +  reset:

I'm not really thrilled how this is evolving with a node per provider. 
There's no reason you can't just add #clock-cells and #reset-cells to 
the parent firmware node.

I probably should have complained with the clocks node, but that's only 
pending for 5.9.

The bigger issue is this stuff is just trickling in one bit at a time 
which gives no context for review. What's next? Is it really a mystery 
as to what functions the firmware provides? You don't have to have a 
driver in place for every function.

Rob

Re: [PATCH v3 1/9] dt-bindings: reset: Add a binding for the RPi Firmware reset controller

[Nicolas Saenz Julienne]

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On Mon, 2020-07-13 at 12:23 -0600, Rob Herring wrote:
> On Fri, Jun 12, 2020 at 07:13:25PM +0200, Nicolas Saenz Julienne wrote:
> > The firmware running on the RPi VideoCore can be used to reset and
> > initialize HW controlled by the firmware.
> > 
> > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> > Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
> > 
> > ---
> > Changes since v2:
> >  - Add include file for reset IDs
> > 
> > Changes since v1:
> >  - Correct cells binding as per Florian's comment
> >  - Change compatible string to be more generic
> > 
> >  .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 21 +++++++++++++++++++
> >  .../reset/raspberrypi,firmware-reset.h        | 13 ++++++++++++
> >  2 files changed, 34 insertions(+)
> >  create mode 100644 include/dt-bindings/reset/raspberrypi,firmware-reset.h
> > 
> > diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > firmware.yaml
> > b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > firmware.yaml
> > index b48ed875eb8e..23a885af3a28 100644
> > --- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > firmware.yaml
> > +++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > firmware.yaml
> > @@ -39,6 +39,22 @@ properties:
> >        - compatible
> >        - "#clock-cells"
> >  
> > +  reset:
> 
> I'm not really thrilled how this is evolving with a node per provider. 
> There's no reason you can't just add #clock-cells and #reset-cells to 
> the parent firmware node.

What are the downsides? The way I see it there is not much difference. And this
way of handling things is feels more intuitive and flexible (overlays can
control what to enable easily, we can take advantage of the platform device
core).

> I probably should have complained with the clocks node, but that's only 
> pending for 5.9.

Note that there are more users for this pattern: "raspberrypi,firmware-ts" and
"raspberrypi,firmware-gpio". Actually you were the one to originally propose
this it[1]. :P

There already is a fair amount of churn in these drivers because of all the DT
changes we did in the past, and if we need to change how we integrate these
again, I'd really like it to be for good.

> The bigger issue is this stuff is just trickling in one bit at a time 
> which gives no context for review. What's next? Is it really a mystery 
> as to what functions the firmware provides?

We have no control over it, RPi engineers integrate new designs and new
firmware interfaces show up. This is a good example of it.

I proposed them to use SCMI as it covers most of what they are already
providing here. But no luck so far.

> You don't have to have a driver in place for every function.

I see your point, it could be more monolithic, that said, having a driver is
essential. See the reverts I managed to pull off at the end of the series.

[1] https://patchwork.kernel.org/patch/10166783/#21421571


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Re: [PATCH v3 1/9] dt-bindings: reset: Add a binding for the RPi Firmware reset controller

[Rob Herring]

On Tue, Jul 14, 2020 at 01:59:21PM +0200, Nicolas Saenz Julienne wrote:
> On Mon, 2020-07-13 at 12:23 -0600, Rob Herring wrote:
> > On Fri, Jun 12, 2020 at 07:13:25PM +0200, Nicolas Saenz Julienne wrote:
> > > The firmware running on the RPi VideoCore can be used to reset and
> > > initialize HW controlled by the firmware.
> > > 
> > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> > > Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
> > > 
> > > ---
> > > Changes since v2:
> > >  - Add include file for reset IDs
> > > 
> > > Changes since v1:
> > >  - Correct cells binding as per Florian's comment
> > >  - Change compatible string to be more generic
> > > 
> > >  .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 21 +++++++++++++++++++
> > >  .../reset/raspberrypi,firmware-reset.h        | 13 ++++++++++++
> > >  2 files changed, 34 insertions(+)
> > >  create mode 100644 include/dt-bindings/reset/raspberrypi,firmware-reset.h
> > > 
> > > diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > > firmware.yaml
> > > b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > > firmware.yaml
> > > index b48ed875eb8e..23a885af3a28 100644
> > > --- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > > firmware.yaml
> > > +++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> > > firmware.yaml
> > > @@ -39,6 +39,22 @@ properties:
> > >        - compatible
> > >        - "#clock-cells"
> > >  
> > > +  reset:
> > 
> > I'm not really thrilled how this is evolving with a node per provider. 
> > There's no reason you can't just add #clock-cells and #reset-cells to 
> > the parent firmware node.
> 
> What are the downsides? The way I see it there is not much difference. And this
> way of handling things is feels more intuitive and flexible (overlays can
> control what to enable easily, we can take advantage of the platform device
> core).

What the OS wants can evolve, so designing around the current needs of 
the OS is not how bindings should be done.

Using overlays to add clocks or resets wouldn't really work given they 
are spread out over the tree. And with clocks in particular, you'd have 
to replace dummy fixed clocks with actual firmware clocks. Sounds 
fragile and messy...

> > I probably should have complained with the clocks node, but that's only 
> > pending for 5.9.
> 
> Note that there are more users for this pattern: "raspberrypi,firmware-ts" and
> "raspberrypi,firmware-gpio". Actually you were the one to originally propose
> this it[1]. :P

Sigh, this is why I dislike incomplete examples...

Based on that,

Acked-by: Rob Herring <robh@kernel.org>

And please get gpio and ts converted to schema and referenced here 
before the next time I look at this.

> There already is a fair amount of churn in these drivers because of all the DT
> changes we did in the past, and if we need to change how we integrate these
> again, I'd really like it to be for good.
> 
> > The bigger issue is this stuff is just trickling in one bit at a time 
> > which gives no context for review. What's next? Is it really a mystery 
> > as to what functions the firmware provides?
> 
> We have no control over it, RPi engineers integrate new designs and new
> firmware interfaces show up. This is a good example of it.
> 
> I proposed them to use SCMI as it covers most of what they are already
> providing here. But no luck so far.

Once we get tired of supporting all the different firmware interfaces 
and the mess they become, we'll just have to start refusing custom ones. 
Worked for PSCI.

> > You don't have to have a driver in place for every function.
> 
> I see your point, it could be more monolithic, that said, having a driver is
> essential. See the reverts I managed to pull off at the end of the series.
> 
> [1] https://patchwork.kernel.org/patch/10166783/#21421571
> 

Re: [PATCH v3 1/9] dt-bindings: reset: Add a binding for the RPi Firmware reset controller

[Florian Fainelli]

On 7/14/2020 2:07 PM, Rob Herring wrote:
> On Tue, Jul 14, 2020 at 01:59:21PM +0200, Nicolas Saenz Julienne wrote:
>> On Mon, 2020-07-13 at 12:23 -0600, Rob Herring wrote:
>>> On Fri, Jun 12, 2020 at 07:13:25PM +0200, Nicolas Saenz Julienne wrote:
>>>> The firmware running on the RPi VideoCore can be used to reset and
>>>> initialize HW controlled by the firmware.
>>>>
>>>> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
>>>> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
>>>>
>>>> ---
>>>> Changes since v2:
>>>>  - Add include file for reset IDs
>>>>
>>>> Changes since v1:
>>>>  - Correct cells binding as per Florian's comment
>>>>  - Change compatible string to be more generic
>>>>
>>>>  .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 21 +++++++++++++++++++
>>>>  .../reset/raspberrypi,firmware-reset.h        | 13 ++++++++++++
>>>>  2 files changed, 34 insertions(+)
>>>>  create mode 100644 include/dt-bindings/reset/raspberrypi,firmware-reset.h
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
>>>> firmware.yaml
>>>> b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
>>>> firmware.yaml
>>>> index b48ed875eb8e..23a885af3a28 100644
>>>> --- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
>>>> firmware.yaml
>>>> +++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
>>>> firmware.yaml
>>>> @@ -39,6 +39,22 @@ properties:
>>>>        - compatible
>>>>        - "#clock-cells"
>>>>  
>>>> +  reset:
>>>
>>> I'm not really thrilled how this is evolving with a node per provider. 
>>> There's no reason you can't just add #clock-cells and #reset-cells to 
>>> the parent firmware node.
>>
>> What are the downsides? The way I see it there is not much difference. And this
>> way of handling things is feels more intuitive and flexible (overlays can
>> control what to enable easily, we can take advantage of the platform device
>> core).
> 
> What the OS wants can evolve, so designing around the current needs of 
> the OS is not how bindings should be done.
> 
> Using overlays to add clocks or resets wouldn't really work given they 
> are spread out over the tree. And with clocks in particular, you'd have 
> to replace dummy fixed clocks with actual firmware clocks. Sounds 
> fragile and messy...
> 
>>> I probably should have complained with the clocks node, but that's only 
>>> pending for 5.9.
>>
>> Note that there are more users for this pattern: "raspberrypi,firmware-ts" and
>> "raspberrypi,firmware-gpio". Actually you were the one to originally propose
>> this it[1]. :P
> 
> Sigh, this is why I dislike incomplete examples...
> 
> Based on that,
> 
> Acked-by: Rob Herring <robh@kernel.org>
> 
> And please get gpio and ts converted to schema and referenced here 
> before the next time I look at this.
> 
>> There already is a fair amount of churn in these drivers because of all the DT
>> changes we did in the past, and if we need to change how we integrate these
>> again, I'd really like it to be for good.
>>
>>> The bigger issue is this stuff is just trickling in one bit at a time 
>>> which gives no context for review. What's next? Is it really a mystery 
>>> as to what functions the firmware provides?
>>
>> We have no control over it, RPi engineers integrate new designs and new
>> firmware interfaces show up. This is a good example of it.
>>
>> I proposed them to use SCMI as it covers most of what they are already
>> providing here. But no luck so far.
> 
> Once we get tired of supporting all the different firmware interfaces 
> and the mess they become, we'll just have to start refusing custom ones. 
> Worked for PSCI.

In this particular case, the Raspberry Pi Foundation VPU firmware should
just implement SCMI and that would avoid having to write new client
drivers for Linux, it is not clear to me why this has not been done yet.
-- 
Florian

Re: [PATCH v3 1/9] dt-bindings: reset: Add a binding for the RPi Firmware reset controller

[Rob Herring]

On Tue, Jul 14, 2020 at 3:18 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
>
>
>
> On 7/14/2020 2:07 PM, Rob Herring wrote:
> > On Tue, Jul 14, 2020 at 01:59:21PM +0200, Nicolas Saenz Julienne wrote:
> >> On Mon, 2020-07-13 at 12:23 -0600, Rob Herring wrote:
> >>> On Fri, Jun 12, 2020 at 07:13:25PM +0200, Nicolas Saenz Julienne wrote:
> >>>> The firmware running on the RPi VideoCore can be used to reset and
> >>>> initialize HW controlled by the firmware.
> >>>>
> >>>> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> >>>> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
> >>>>
> >>>> ---
> >>>> Changes since v2:
> >>>>  - Add include file for reset IDs
> >>>>
> >>>> Changes since v1:
> >>>>  - Correct cells binding as per Florian's comment
> >>>>  - Change compatible string to be more generic
> >>>>
> >>>>  .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 21 +++++++++++++++++++
> >>>>  .../reset/raspberrypi,firmware-reset.h        | 13 ++++++++++++
> >>>>  2 files changed, 34 insertions(+)
> >>>>  create mode 100644 include/dt-bindings/reset/raspberrypi,firmware-reset.h
> >>>>
> >>>> diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> >>>> firmware.yaml
> >>>> b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> >>>> firmware.yaml
> >>>> index b48ed875eb8e..23a885af3a28 100644
> >>>> --- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> >>>> firmware.yaml
> >>>> +++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
> >>>> firmware.yaml
> >>>> @@ -39,6 +39,22 @@ properties:
> >>>>        - compatible
> >>>>        - "#clock-cells"
> >>>>
> >>>> +  reset:
> >>>
> >>> I'm not really thrilled how this is evolving with a node per provider.
> >>> There's no reason you can't just add #clock-cells and #reset-cells to
> >>> the parent firmware node.
> >>
> >> What are the downsides? The way I see it there is not much difference. And this
> >> way of handling things is feels more intuitive and flexible (overlays can
> >> control what to enable easily, we can take advantage of the platform device
> >> core).
> >
> > What the OS wants can evolve, so designing around the current needs of
> > the OS is not how bindings should be done.
> >
> > Using overlays to add clocks or resets wouldn't really work given they
> > are spread out over the tree. And with clocks in particular, you'd have
> > to replace dummy fixed clocks with actual firmware clocks. Sounds
> > fragile and messy...
> >
> >>> I probably should have complained with the clocks node, but that's only
> >>> pending for 5.9.
> >>
> >> Note that there are more users for this pattern: "raspberrypi,firmware-ts" and
> >> "raspberrypi,firmware-gpio". Actually you were the one to originally propose
> >> this it[1]. :P
> >
> > Sigh, this is why I dislike incomplete examples...
> >
> > Based on that,
> >
> > Acked-by: Rob Herring <robh@kernel.org>
> >
> > And please get gpio and ts converted to schema and referenced here
> > before the next time I look at this.
> >
> >> There already is a fair amount of churn in these drivers because of all the DT
> >> changes we did in the past, and if we need to change how we integrate these
> >> again, I'd really like it to be for good.
> >>
> >>> The bigger issue is this stuff is just trickling in one bit at a time
> >>> which gives no context for review. What's next? Is it really a mystery
> >>> as to what functions the firmware provides?
> >>
> >> We have no control over it, RPi engineers integrate new designs and new
> >> firmware interfaces show up. This is a good example of it.
> >>
> >> I proposed them to use SCMI as it covers most of what they are already
> >> providing here. But no luck so far.
> >
> > Once we get tired of supporting all the different firmware interfaces
> > and the mess they become, we'll just have to start refusing custom ones.
> > Worked for PSCI.
>
> In this particular case, the Raspberry Pi Foundation VPU firmware should
> just implement SCMI and that would avoid having to write new client
> drivers for Linux, it is not clear to me why this has not been done yet.

Writing drivers is fun?

Perhaps we should start refusing new firmware interfaces now.

Rob