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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Cc: "Manivannan Sadhasivam" <manivannan.sadhasivam@linaro.org>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	"Linux Media Mailing List" <linux-media@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Kieran Bingham" <kieran.bingham@ideasonboard.com>,
	"Laurent Pinchart" <laurent.pinchart@ideasonboard.com>,
	"Jacopo Mondi" <jacopo@jmondi.org>,
	"Niklas Söderlund" <niklas.soderlund@ragnatech.se>,
	"Sakari Ailus" <sakari.ailus@iki.fi>,
	"Hans Verkuil" <hverkuil@xs4all.nl>,
	"Hyun Kwon" <hyunk@xilinx.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Jacopo Mondi" <jacopo+renesas@jmondi.org>,
	"Laurent Pinchart" <laurent.pinchart+renesas@ideasonboard.com>,
	"Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>
Subject: Re: [PATCH v9 2/4] media: i2c: Add MAX9286 driver
Date: Thu, 14 May 2020 13:59:35 +0200	[thread overview]
Message-ID: <CAMuHMdWSEY2q1f1iobrSXHYWzweV9yjk4i1ROj2Yde7DJMiabQ@mail.gmail.com> (raw)
In-Reply-To: <d492cbcb-3b13-82b8-8e5d-0f49320170a2@ideasonboard.com>

Hi Kieran,

On Thu, May 14, 2020 at 1:47 PM Kieran Bingham
<kieran.bingham+renesas@ideasonboard.com> wrote:
> On 14/05/2020 11:13, Manivannan Sadhasivam wrote:
> > On Thu, May 14, 2020 at 11:02:53AM +0100, Kieran Bingham wrote:
> >> On 12/05/2020 19:17, Manivannan Sadhasivam wrote:
> >>> On Tue, May 12, 2020 at 04:51:03PM +0100, Kieran Bingham wrote:
> >>>> The MAX9286 is a 4-channel GMSL deserializer with coax or STP input and
> >>>> CSI-2 output. The device supports multicamera streaming applications,
> >>>> and features the ability to synchronise the attached cameras.
> >>>>
> >>>> CSI-2 output can be configured with 1 to 4 lanes, and a control channel
> >>>> is supported over I2C, which implements an I2C mux to facilitate
> >>>> communications with connected cameras across the reverse control
> >>>> channel.
> >>>>
> >>>> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> >>>> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> >>>> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> >>>> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> >>>> --- /dev/null
> >>>> +++ b/drivers/media/i2c/max9286.c

> >>>> +static int max9286_register_gpio(struct max9286_priv *priv)
> >>>> +{
> >>>> +  struct device *dev = &priv->client->dev;
> >>>> +  struct gpio_chip *gpio = &priv->gpio;
> >>>> +  int ret;
> >>>> +
> >>>> +  static const char * const names[] = {
> >>>> +          "GPIO0OUT",
> >>>> +          "GPIO1OUT",
> >>>> +  };
> >>>> +
> >>>> +  /* Configure the GPIO */
> >>>> +  gpio->label = dev_name(dev);
> >>>
> >>> So if you have more than one MAX9286 in a system, all gpiochips will appear
> >>> with the same name. I'd recommend to append the index to distinguish properly.
> >>
> >> Ah yes, that's a good point, and I think I've even seen that.
> >>
> >> I'll fix it now.
>
> Oh, in fact actually this doesn't.
>
> gpiodetect prints:
>
> gpiochip10 [4-004c] (2 lines)
> gpiochip11 [4-006c] (2 lines)
>
> and mostly references them as gpiochip10 and gpiochip11.

Indeed, dev_name() should be different for each instance.

> However,
>
> > [    2.318533] gpio gpiochip11: Detected name collision for GPIO name 'GPIO0OUT'
> > [    2.325739] gpio gpiochip11: Detected name collision for GPIO name 'GPIO1OUT'
>
> That seems to be more of a problem for the gpio library, so I think I'll
> just drop the const names. I don't think they add much value.

These are the line names.  If they're not unique, a warning is printed,
but they are still registered.
So probably you want to use kasprintf("%s.%s", dev_name(dev), names[i]) to
generate names.

See "[PATCH] gpiolib: Document that GPIO line names are not globally unique"
(https://lore.kernel.org/linux-gpio/20200511101828.30046-1-geert+renesas@glider.be/)
to clear up the details.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

  reply	other threads:[~2020-05-14 11:59 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-12 15:51 [PATCH v9 0/4] MAX9286 GMSL Support (+RDACM20) Kieran Bingham
2020-05-12 15:51 ` [PATCH v9 1/4] dt-bindings: media: i2c: Add bindings for Maxim Integrated MAX9286 Kieran Bingham
2020-05-12 22:33   ` Rob Herring
2020-05-12 22:36   ` Rob Herring
2020-05-13 12:28     ` Jacopo Mondi
2020-05-12 15:51 ` [PATCH v9 2/4] media: i2c: Add MAX9286 driver Kieran Bingham
2020-05-12 17:40   ` Manivannan Sadhasivam
2020-05-14  9:53     ` Kieran Bingham
2020-05-14  9:59       ` Manivannan Sadhasivam
2020-05-14 10:05         ` Kieran Bingham
2020-05-12 18:17   ` Manivannan Sadhasivam
2020-05-14 10:02     ` Kieran Bingham
2020-05-14 10:13       ` Manivannan Sadhasivam
2020-05-14 11:47         ` Kieran Bingham
2020-05-14 11:59           ` Geert Uytterhoeven [this message]
2020-05-14 12:48             ` Manivannan Sadhasivam
2020-05-14 13:50               ` Kieran Bingham
2020-05-14 11:47         ` Kieran Bingham
2020-05-14 12:27           ` Kieran Bingham
2020-05-14 12:54             ` Manivannan Sadhasivam
2020-05-16 21:51   ` Sakari Ailus
2020-05-18 11:45     ` Kieran Bingham
2020-05-18 12:38       ` Jacopo Mondi
2020-05-18 13:09         ` Kieran Bingham
2020-05-19  8:10       ` Sakari Ailus
2020-05-19  8:55         ` Kieran Bingham
2020-05-19  9:03           ` Sakari Ailus
2020-05-20  0:50       ` Laurent Pinchart
2020-05-26  8:54         ` Sakari Ailus
2020-05-12 15:51 ` [PATCH v9 3/4] dt-bindings: media: i2c: Add bindings for IMI RDACM2x Kieran Bingham
2020-05-12 15:51 ` [PATCH v9 4/4] media: i2c: Add RDACM20 driver Kieran Bingham
2020-05-16 22:36   ` Sakari Ailus
2020-05-18  7:35     ` Jacopo Mondi

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