diff mbox series

[v4,1/2] dt-bindings: Add bindings for BrcmSTB SCMI mailbox driver

Message ID 20201029195913.5927-2-james.quinlan@broadcom.com
State Changes Requested
Headers show
Series mailbox: Add Broadcom STB mailbox driver for SCMI | expand

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Commit Message

Jim Quinlan Oct. 29, 2020, 7:59 p.m. UTC
Bindings are added.  Only one interrupt is needed because
we do not yet employ the SCMI p2a channel.

Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
---
 .../bindings/mailbox/brcm,brcmstb-mbox.yaml   | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml

Comments

Rob Herring Nov. 4, 2020, 9:50 p.m. UTC | #1
On Thu, Oct 29, 2020 at 03:59:06PM -0400, Jim Quinlan wrote:
> Bindings are added.  Only one interrupt is needed because
> we do not yet employ the SCMI p2a channel.

I still don't understand what this is. To repeat from v1: I thought SCMI 
was a mailbox consumer, not provider?

> 
> Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
> ---
>  .../bindings/mailbox/brcm,brcmstb-mbox.yaml   | 39 +++++++++++++++++++
>  1 file changed, 39 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml
> 
> diff --git a/Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml b/Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml
> new file mode 100644
> index 000000000000..797c0cc609a3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml
> @@ -0,0 +1,39 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> +$id: http://devicetree.org/schemas/mailbox/brcm,brcmstb-mbox.yaml#
> +
> +title: Broadcom STB mailbox driver bindings
> +
> +maintainers:
> +  - Jim Quinlan <james.quinlan@broadcom.com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - brcm,brcmstb-mbox
> +
> +  interrupts:
> +    items:
> +      - description: a2p return interrupt, indicates SCMI msg completion.
> +
> +  "#mbox-cells":
> +    const: 1
> +
> +required:
> +  - compatible
> +  - interrupts
> +  - "#mbox-cells"
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    mailbox {
> +      compatible = "brcm,brcmstb-mailbox";
> +      #mbox-cells = <1>;
> +      interrupts = <GIC_SPI 0xc6 IRQ_TYPE_LEVEL_HIGH>;
> +    };
> +...
> -- 
> 2.17.1
>
Jim Quinlan Nov. 4, 2020, 10:03 p.m. UTC | #2
On Wed, Nov 4, 2020 at 4:50 PM Rob Herring <robh@kernel.org> wrote:
>
> On Thu, Oct 29, 2020 at 03:59:06PM -0400, Jim Quinlan wrote:
> > Bindings are added.  Only one interrupt is needed because
> > we do not yet employ the SCMI p2a channel.
>
> I still don't understand what this is. To repeat from v1: I thought SCMI
> was a mailbox consumer, not provider?

Hi Rob,

I'm not sure where I am implying that SCMI is a mailbox provider?
Should I not mention "SCMI" in the subject line?

This is just a mailbox driver, "consumed" by SCMI.    Our SCMI DT node
looks like this:

brcm_scmi_mailbox: brcm_scmi_mailbox@0 {
        #mbox-cells = <1>;
        compatible = "brcm,brcmstb-mbox";
};

brcm_scmi@0 {
        compatible = "arm,scmi";
        mboxes = <&brcm_scmi_mailbox 0>;;
        mbox-names = "tx";
        shmem = <&NWMBOX>;
        /* ... */
};

Please advise,
Jim Quinlan
Broadcom STB

>
> >
> > Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
> > ---
> >  .../bindings/mailbox/brcm,brcmstb-mbox.yaml   | 39 +++++++++++++++++++
> >  1 file changed, 39 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml b/Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml
> > new file mode 100644
> > index 000000000000..797c0cc609a3
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml
> > @@ -0,0 +1,39 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> > +$id: http://devicetree.org/schemas/mailbox/brcm,brcmstb-mbox.yaml#
> > +
> > +title: Broadcom STB mailbox driver bindings
> > +
> > +maintainers:
> > +  - Jim Quinlan <james.quinlan@broadcom.com>
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - brcm,brcmstb-mbox
> > +
> > +  interrupts:
> > +    items:
> > +      - description: a2p return interrupt, indicates SCMI msg completion.
> > +
> > +  "#mbox-cells":
> > +    const: 1
> > +
> > +required:
> > +  - compatible
> > +  - interrupts
> > +  - "#mbox-cells"
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> > +    mailbox {
> > +      compatible = "brcm,brcmstb-mailbox";
> > +      #mbox-cells = <1>;
> > +      interrupts = <GIC_SPI 0xc6 IRQ_TYPE_LEVEL_HIGH>;
> > +    };
> > +...
> > --
> > 2.17.1
> >
>
>
Rob Herring Nov. 5, 2020, 3:13 p.m. UTC | #3
On Wed, Nov 4, 2020 at 4:04 PM Jim Quinlan <james.quinlan@broadcom.com> wrote:
>
> On Wed, Nov 4, 2020 at 4:50 PM Rob Herring <robh@kernel.org> wrote:
> >
> > On Thu, Oct 29, 2020 at 03:59:06PM -0400, Jim Quinlan wrote:
> > > Bindings are added.  Only one interrupt is needed because
> > > we do not yet employ the SCMI p2a channel.
> >
> > I still don't understand what this is. To repeat from v1: I thought SCMI
> > was a mailbox consumer, not provider?
>
> Hi Rob,
>
> I'm not sure where I am implying that SCMI is a mailbox provider?
> Should I not mention "SCMI" in the subject line?
>
> This is just a mailbox driver, "consumed" by SCMI.    Our SCMI DT node
> looks like this:
>
> brcm_scmi_mailbox: brcm_scmi_mailbox@0 {
>         #mbox-cells = <1>;
>         compatible = "brcm,brcmstb-mbox";
> };
>
> brcm_scmi@0 {
>         compatible = "arm,scmi";
>         mboxes = <&brcm_scmi_mailbox 0>;;
>         mbox-names = "tx";
>         shmem = <&NWMBOX>;
>         /* ... */
> };

Okay, that makes more sense. Though it seems like this is just adding
a pointless level of indirection to turn an interrupt into a mailbox.
There's nothing more to 'the mailbox' is there? So why not either
allow SCMI to have an interrupt directly or have a generic irq mailbox
driver?

Rob
Jim Quinlan Nov. 5, 2020, 3:28 p.m. UTC | #4
On Thu, Nov 5, 2020 at 10:13 AM Rob Herring <robh@kernel.org> wrote:
>
> On Wed, Nov 4, 2020 at 4:04 PM Jim Quinlan <james.quinlan@broadcom.com> wrote:
> >
> > On Wed, Nov 4, 2020 at 4:50 PM Rob Herring <robh@kernel.org> wrote:
> > >
> > > On Thu, Oct 29, 2020 at 03:59:06PM -0400, Jim Quinlan wrote:
> > > > Bindings are added.  Only one interrupt is needed because
> > > > we do not yet employ the SCMI p2a channel.
> > >
> > > I still don't understand what this is. To repeat from v1: I thought SCMI
> > > was a mailbox consumer, not provider?
> >
> > Hi Rob,
> >
> > I'm not sure where I am implying that SCMI is a mailbox provider?
> > Should I not mention "SCMI" in the subject line?
> >
> > This is just a mailbox driver, "consumed" by SCMI.    Our SCMI DT node
> > looks like this:
> >
> > brcm_scmi_mailbox: brcm_scmi_mailbox@0 {
> >         #mbox-cells = <1>;
> >         compatible = "brcm,brcmstb-mbox";
> > };
> >
> > brcm_scmi@0 {
> >         compatible = "arm,scmi";
> >         mboxes = <&brcm_scmi_mailbox 0>;;
> >         mbox-names = "tx";
> >         shmem = <&NWMBOX>;
> >         /* ... */
> > };
>
> Okay, that makes more sense. Though it seems like this is just adding
> a pointless level of indirection to turn an interrupt into a mailbox.
> There's nothing more to 'the mailbox' is there?
Correct.  Although you can see that it uses both interrupts and SMC
calls to get the job done.

> So why not either
> allow SCMI to have an interrupt directly
Not sure here -- perhaps the SCMI folks have an answer?

 > or have a generic irq mailbox
> driver?
The SCMI implementation doesn't offer a generic irq mailbox driver
AFAICT.  The SCMI folks recently provided  an "smc transport" driver
in "drivers/firmware/arm_scmi/smc.c" -- it is close to what we need
but is missing interrupts.

Regards,
Jim Quinlan
Broadcom STB

>
> Rob
Sudeep Holla Nov. 5, 2020, 6:27 p.m. UTC | #5
On Thu, Nov 05, 2020 at 10:28:25AM -0500, Jim Quinlan wrote:
> On Thu, Nov 5, 2020 at 10:13 AM Rob Herring <robh@kernel.org> wrote:
> >
> > On Wed, Nov 4, 2020 at 4:04 PM Jim Quinlan <james.quinlan@broadcom.com> wrote:
> > >
> > > On Wed, Nov 4, 2020 at 4:50 PM Rob Herring <robh@kernel.org> wrote:
> > > >
> > > > On Thu, Oct 29, 2020 at 03:59:06PM -0400, Jim Quinlan wrote:
> > > > > Bindings are added.  Only one interrupt is needed because
> > > > > we do not yet employ the SCMI p2a channel.
> > > >
> > > > I still don't understand what this is. To repeat from v1: I thought SCMI
> > > > was a mailbox consumer, not provider?
> > >
> > > Hi Rob,
> > >
> > > I'm not sure where I am implying that SCMI is a mailbox provider?
> > > Should I not mention "SCMI" in the subject line?
> > >
> > > This is just a mailbox driver, "consumed" by SCMI.    Our SCMI DT node
> > > looks like this:
> > >
> > > brcm_scmi_mailbox: brcm_scmi_mailbox@0 {
> > >         #mbox-cells = <1>;
> > >         compatible = "brcm,brcmstb-mbox";
> > > };
> > >
> > > brcm_scmi@0 {
> > >         compatible = "arm,scmi";
> > >         mboxes = <&brcm_scmi_mailbox 0>;;
> > >         mbox-names = "tx";
> > >         shmem = <&NWMBOX>;
> > >         /* ... */
> > > };
> >
> > Okay, that makes more sense. Though it seems like this is just adding
> > a pointless level of indirection to turn an interrupt into a mailbox.
> > There's nothing more to 'the mailbox' is there?
>
> Correct.  Although you can see that it uses both interrupts and SMC
> calls to get the job done.
>

I was against having 2 separate solutions and would have raised my concern
again. As I mentioned earlier, either extend what we have or move the
existing SMC solution into this mailbox driver. Having 2 different solution
for this just because you have extra interrupt to deal with is definite
NACK from me as I had previously mentioned.

> > So why not either
> > allow SCMI to have an interrupt directly
> Not sure here -- perhaps the SCMI folks have an answer?
>

I did ask why can't you extend the existing SCMI/SMC binding to add this
as optional feature ?

> > or have a generic irq mailbox driver?

Fine with this too.

> The SCMI implementation doesn't offer a generic irq mailbox driver
> AFAICT.  The SCMI folks recently provided  an "smc transport" driver
> in "drivers/firmware/arm_scmi/smc.c" -- it is close to what we need
> but is missing interrupts.

IIRC, you were using SGIs and it can't be represented and use today as
is ? Am  I missing something or anything has changed ?

--
Regards,
Sudeep
Jim Quinlan Nov. 5, 2020, 6:57 p.m. UTC | #6
On Thu, Nov 5, 2020 at 1:27 PM Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Thu, Nov 05, 2020 at 10:28:25AM -0500, Jim Quinlan wrote:
> > On Thu, Nov 5, 2020 at 10:13 AM Rob Herring <robh@kernel.org> wrote:
> > >
> > > On Wed, Nov 4, 2020 at 4:04 PM Jim Quinlan <james.quinlan@broadcom.com> wrote:
> > > >
> > > > On Wed, Nov 4, 2020 at 4:50 PM Rob Herring <robh@kernel.org> wrote:
> > > > >
> > > > > On Thu, Oct 29, 2020 at 03:59:06PM -0400, Jim Quinlan wrote:
> > > > > > Bindings are added.  Only one interrupt is needed because
> > > > > > we do not yet employ the SCMI p2a channel.
> > > > >
> > > > > I still don't understand what this is. To repeat from v1: I thought SCMI
> > > > > was a mailbox consumer, not provider?
> > > >
> > > > Hi Rob,
> > > >
> > > > I'm not sure where I am implying that SCMI is a mailbox provider?
> > > > Should I not mention "SCMI" in the subject line?
> > > >
> > > > This is just a mailbox driver, "consumed" by SCMI.    Our SCMI DT node
> > > > looks like this:
> > > >
> > > > brcm_scmi_mailbox: brcm_scmi_mailbox@0 {
> > > >         #mbox-cells = <1>;
> > > >         compatible = "brcm,brcmstb-mbox";
> > > > };
> > > >
> > > > brcm_scmi@0 {
> > > >         compatible = "arm,scmi";
> > > >         mboxes = <&brcm_scmi_mailbox 0>;;
> > > >         mbox-names = "tx";
> > > >         shmem = <&NWMBOX>;
> > > >         /* ... */
> > > > };
> > >
> > > Okay, that makes more sense. Though it seems like this is just adding
> > > a pointless level of indirection to turn an interrupt into a mailbox.
> > > There's nothing more to 'the mailbox' is there?
> >
> > Correct.  Although you can see that it uses both interrupts and SMC
> > calls to get the job done.
> >
>
> I was against having 2 separate solutions and would have raised my concern
> again. As I mentioned earlier, either extend what we have or move the
> existing SMC solution into this mailbox driver. Having 2 different solution
> for this just because you have extra interrupt to deal with is definite
> NACK from me as I had previously mentioned.
>
> > > So why not either
> > > allow SCMI to have an interrupt directly
> > Not sure here -- perhaps the SCMI folks have an answer?
> >
>
> I did ask why can't you extend the existing SCMI/SMC binding to add this
> as optional feature ?
Hi Sudeep,

Looking at the email you said, "In that case any reason why you can't
reuse the existing smc transport for SCMI." ,  and I replied with the
reason.  I did not interpret your statement  above as what you are
clearly saying now: "either extend what we have or move the existing
SMC solution into this mailbox driver. "

Fair enough, I  will look into this.

Regards,
Jim


>
> > > or have a generic irq mailbox driver?
>
> Fine with this too.
>
> > The SCMI implementation doesn't offer a generic irq mailbox driver
> > AFAICT.  The SCMI folks recently provided  an "smc transport" driver
> > in "drivers/firmware/arm_scmi/smc.c" -- it is close to what we need
> > but is missing interrupts.
>
> IIRC, you were using SGIs and it can't be represented and use today as
> is ? Am  I missing something or anything has changed ?
>
> --
> Regards,
> Sudeep
Sudeep Holla Nov. 5, 2020, 7:05 p.m. UTC | #7
On Thu, Nov 05, 2020 at 01:57:07PM -0500, Jim Quinlan wrote:
> On Thu, Nov 5, 2020 at 1:27 PM Sudeep Holla <sudeep.holla@arm.com> wrote:
> >
> > On Thu, Nov 05, 2020 at 10:28:25AM -0500, Jim Quinlan wrote:
> > > On Thu, Nov 5, 2020 at 10:13 AM Rob Herring <robh@kernel.org> wrote:
> > > >
> > > > On Wed, Nov 4, 2020 at 4:04 PM Jim Quinlan <james.quinlan@broadcom.com> wrote:
> > > > >
> > > > > On Wed, Nov 4, 2020 at 4:50 PM Rob Herring <robh@kernel.org> wrote:
> > > > > >
> > > > > > On Thu, Oct 29, 2020 at 03:59:06PM -0400, Jim Quinlan wrote:
> > > > > > > Bindings are added.  Only one interrupt is needed because
> > > > > > > we do not yet employ the SCMI p2a channel.
> > > > > >
> > > > > > I still don't understand what this is. To repeat from v1: I thought SCMI
> > > > > > was a mailbox consumer, not provider?
> > > > >
> > > > > Hi Rob,
> > > > >
> > > > > I'm not sure where I am implying that SCMI is a mailbox provider?
> > > > > Should I not mention "SCMI" in the subject line?
> > > > >
> > > > > This is just a mailbox driver, "consumed" by SCMI.    Our SCMI DT node
> > > > > looks like this:
> > > > >
> > > > > brcm_scmi_mailbox: brcm_scmi_mailbox@0 {
> > > > >         #mbox-cells = <1>;
> > > > >         compatible = "brcm,brcmstb-mbox";
> > > > > };
> > > > >
> > > > > brcm_scmi@0 {
> > > > >         compatible = "arm,scmi";
> > > > >         mboxes = <&brcm_scmi_mailbox 0>;;
> > > > >         mbox-names = "tx";
> > > > >         shmem = <&NWMBOX>;
> > > > >         /* ... */
> > > > > };
> > > >
> > > > Okay, that makes more sense. Though it seems like this is just adding
> > > > a pointless level of indirection to turn an interrupt into a mailbox.
> > > > There's nothing more to 'the mailbox' is there?
> > >
> > > Correct.  Although you can see that it uses both interrupts and SMC
> > > calls to get the job done.
> > >
> >
> > I was against having 2 separate solutions and would have raised my concern
> > again. As I mentioned earlier, either extend what we have or move the
> > existing SMC solution into this mailbox driver. Having 2 different solution
> > for this just because you have extra interrupt to deal with is definite
> > NACK from me as I had previously mentioned.
> >
> > > > So why not either
> > > > allow SCMI to have an interrupt directly
> > > Not sure here -- perhaps the SCMI folks have an answer?
> > >
> >
> > I did ask why can't you extend the existing SCMI/SMC binding to add this
> > as optional feature ?
> Hi Sudeep,
> 
> Looking at the email you said, "In that case any reason why you can't
> reuse the existing smc transport for SCMI." ,  and I replied with the
> reason.  I did not interpret your statement  above as what you are
> clearly saying now: "either extend what we have or move the existing
> SMC solution into this mailbox driver. "
>

No, you are right. I didn't mention that explicitly. I wanted to, but
thought I will wait until this driver got traction to ask you to merge
them. Sorry for that. Anyways I am against having existing solution and
a mailbox for SMC, they need to be merged at any cost. Where the final
solution will be doesn't matter much to me, I am fine either way.

--
Regards,
Sudeep
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml b/Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml
new file mode 100644
index 000000000000..797c0cc609a3
--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/brcm,brcmstb-mbox.yaml
@@ -0,0 +1,39 @@ 
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+$id: http://devicetree.org/schemas/mailbox/brcm,brcmstb-mbox.yaml#
+
+title: Broadcom STB mailbox driver bindings
+
+maintainers:
+  - Jim Quinlan <james.quinlan@broadcom.com>
+
+properties:
+  compatible:
+    enum:
+      - brcm,brcmstb-mbox
+
+  interrupts:
+    items:
+      - description: a2p return interrupt, indicates SCMI msg completion.
+
+  "#mbox-cells":
+    const: 1
+
+required:
+  - compatible
+  - interrupts
+  - "#mbox-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    mailbox {
+      compatible = "brcm,brcmstb-mailbox";
+      #mbox-cells = <1>;
+      interrupts = <GIC_SPI 0xc6 IRQ_TYPE_LEVEL_HIGH>;
+    };
+...