linux-kernel - Re: [PATCH v6 2/2] iio: proximity: vl53l0x: add interrupt support

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Message-ID: <20181001194446.2b613a69@archlinux>
Date:   Mon, 1 Oct 2018 19:44:46 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Song Qiang <songqiang1304521@...il.com>
Cc:     Rob Herring <robh@...nel.org>, Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald <pmeerw@...erw.net>,
        Mark Rutland <mark.rutland@....com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Matt Ranostay <matt.ranostay@...sulko.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andreas Klinger <ak@...klinger.de>, linux-iio@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v6 2/2] iio: proximity: vl53l0x: add interrupt support

On Mon, 1 Oct 2018 11:58:14 +0800
Song Qiang <songqiang1304521@...il.com> wrote:

> On Fri, Sep 28, 2018 at 06:52:13PM -0500, Rob Herring wrote:
> > On Fri, Sep 28, 2018 at 4:36 AM Song Qiang <songqiang1304521@...il.com> wrote:  
> > >
> > > On Wed, Sep 26, 2018 at 05:46:18PM -0500, Rob Herring wrote:  
> > > > On Sat, Sep 22, 2018 at 04:05:23PM +0100, Jonathan Cameron wrote:  
> > > > > On Tue, 18 Sep 2018 16:24:22 +0800
> > > > > Song Qiang <songqiang1304521@...il.com> wrote:
> > > > >  
> > > > > > The first version of this driver issues a measuring request and polling
> > > > > > for a status register in the device for measuring completes.
> > > > > > vl53l0x support configuring GPIO1 on it to generate interrupt to
> > > > > > indicate that new measurement is ready. This patch adds support for
> > > > > > using this mechanisim to reduce cpu cost.
> > > > > >
> > > > > > Signed-off-by: Song Qiang <songqiang1304521@...il.com>  
> > > > > Hi Song.
> > > > >
> > > > > Looks correct in principal but a few things to tidy up before
> > > > > this is ready to apply.
> > > > >
> > > > > Also we have an unrelated change in here to check the devices ID.
> > > > > That should be in it's own patch.
> > > > >
> > > > > Thanks,
> > > > >
> > > > > Jonathan  
> > > > > > ---
> > > > > >  .../bindings/iio/proximity/vl53l0x.txt        |  14 +-  
> > > >
> > > > This should have been split with the complete binding in one patch
> > > > rather than piecemeal driver feature by feature.
> > > >  
> > >
> > > Hi Rob,
> > >
> > > A few days ago when I was submitting this driver, I didn't do it very
> > > well, the function of this driver is limited. I added interrupt support
> > > the next day after you acked my first patch. I thought it's not polite
> > > to add something after someone acked that patch, so I send the interrupt
> > > support as a second patch. The first patch is merged to togreg now, but
> > > this doesn't. I don't know when can I add new functions to the code that
> > > just merged to togreg branch, could you offer some suggestions?  
> > 
> > You just needed to state why you didn't add a ack. But really, just
> > don't send things except as RFC until they are "done".
> > 
> > What to do next depends on Jonathan and whether he wants a follow-up
> > patch or he will drop the first one.
> >   
> > > > > >  drivers/iio/proximity/vl53l0x-i2c.c           | 135 +++++++++++++++---
> > > > > >  2 files changed, 129 insertions(+), 20 deletions(-)
> > > > > >
> > > > > > diff --git a/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt b/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt
> > > > > > index ab9a9539fec4..40290f8dd70f 100644
> > > > > > --- a/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt
> > > > > > +++ b/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt
> > > > > > @@ -4,9 +4,21 @@ Required properties:
> > > > > >   - compatible: must be "st,vl53l0x-i2c"  
> > > >
> > > > Is there more than one interface on this device, such as SPI? If not,
> > > > then '-i2c' should be dropped.
> > > >  
> > >
> > > Yes, there is a CCI(Camera Control Interface) for communication.  
> > 
> > Isn't CCI just a subset of I2C? I should clarify my question is
> > whether there's more than 1 mutually exclusive control interface (as
> > many devices have control and data interfaces) where you could have 2
> > different drivers. A common example are devices with I2C and SPI
> > interfaces.
> > 
> > Rob  
> 
> Hi Rob, Jonathan,
> 
> I don't know things about CCI very well, and google also tells me little
> about it. Actually, I found it difficult to find a standard definition
> about it. Then I dug into vl53l0x's API source code, and what I can
> tell is when we use these two interfaces, the whole programming
> framework is different, even though the pysical bus of them are likely
> to be the same. 
> Source code of CCI uses a 'msm_camera_i2c_fn_t' struct and a
> 'v4l2_file_operations' as hardware interfaces for controlling device,
> while the i2c one just uses generic i2c bus interfaces.
> 
> This explanation is for why the file name still contains '-i2c'.
> 
File names are easy to change in future compared to device tree bindings
(which may be fixed for ever in an embedded platform).

So this isn't a problem at all.

Thanks,

Jonathan

> yours,
> Song Qiang