linux-kernel - Re: [PATCH v4 3/8] dt-bindings: i2c: iproc: make 'interrupts' optional

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Message-ID: <CAL_JsqK+QLRp7LqkMzQCXdLPaJU3fbiNWU_uyuPFJ4qDkP=siA@mail.gmail.com>
Date:   Thu, 14 Feb 2019 08:16:21 -0600
From:   Rob Herring <robh@...nel.org>
To:     Ray Jui <ray.jui@...adcom.com>
Cc:     Wolfram Sang <wsa@...-dreams.de>,
        Mark Rutland <mark.rutland@....com>,
        Linux I2C <linux-i2c@...r.kernel.org>,
        devicetree@...r.kernel.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@...adcom.com>,
        Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>
Subject: Re: [PATCH v4 3/8] dt-bindings: i2c: iproc: make 'interrupts' optional

On Wed, Feb 13, 2019 at 4:06 PM Ray Jui <ray.jui@...adcom.com> wrote:
>
> Hi Rob,
>
> On 2/13/2019 1:16 PM, Rob Herring wrote:
> > On Mon, Feb 04, 2019 at 03:15:49PM -0800, Ray Jui wrote:
> >> In prep for the introduction of polling mode into the driver, update the
> >> binding document to make the 'interrupts' property optional
> >>
> >> Signed-off-by: Ray Jui <ray.jui@...adcom.com>
> >> Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>
> >> ---
> >>  .../devicetree/bindings/i2c/brcm,iproc-i2c.txt         | 10 +++++++---
> >>  1 file changed, 7 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/i2c/brcm,iproc-i2c.txt b/Documentation/devicetree/bindings/i2c/brcm,iproc-i2c.txt
> >> index 81f982ccca31..d3a3620b1f06 100644
> >> --- a/Documentation/devicetree/bindings/i2c/brcm,iproc-i2c.txt
> >> +++ b/Documentation/devicetree/bindings/i2c/brcm,iproc-i2c.txt
> >> @@ -9,9 +9,6 @@ Required properties:
> >>      Define the base and range of the I/O address space that contain the iProc
> >>      I2C controller registers
> >>
> >> -- interrupts:
> >> -    Should contain the I2C interrupt
> >> -
> >>  - clock-frequency:
> >>      This is the I2C bus clock. Need to be either 100000 or 400000
> >>
> >> @@ -21,6 +18,13 @@ Required properties:
> >>  - #size-cells:
> >>      Always 0
> >>
> >> +Optional properties:
> >> +
> >> +- interrupts:
> >> +    Should contain the I2C interrupt. If unspecified, driver will fall back to
> >> +    polling mode
> >
> > What determines when you want to use polling mode? I'm not sure DT
> > is the best way to control this unless it's really a property of
> > the h/w. Driver behavior is really outside the scope of the DT. u-boot
> > would use polling even if an interrupt is specified, for example.
> >
> It's tied to the particular revision of the I2C controller, i.e., the
> iProc NIC i2c controller does not have interrupt line wired. In this
> case, the behavior is determined by the DT compatible string of the
> iProc I2C device. I thought that it makes sense to now move the
> 'interrupts' property to be under "Optional" than "Required" which is
> basically what this change is.

Okay, please put this detail into the commit msg.

Rob