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From: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>
Cc: 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 14:50:27 +0100	[thread overview]
Message-ID: <8f1b0a8a-35b2-1d00-c156-74d9ec3058d6@ideasonboard.com> (raw)
In-Reply-To: <20200514124831.GG2877@Mani-XPS-13-9360>

On 14/05/2020 13:48, Manivannan Sadhasivam wrote:
> On Thu, May 14, 2020 at 01:59:35PM +0200, Geert Uytterhoeven wrote:
>> 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.
>>
> 
> Ah, my bad! Somehow I got confused that this delivers static name... Sorry for
> the noise, Kieran.
> 
>>> 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.
>>
> 
> Well, I should've pointed this instead of above...
> 
> (lack of coffee)
> 
>> 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.
>>
> 
> Ack.
> 
> I think you should CC Linus W for next iteration to get review for gpiolib
> implementation.

Good idea. I think I'll drop the names though for now.

--
Kieran


> 
> Thanks,
> Mani
> 
>> 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 13:50 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
2020-05-14 12:48             ` Manivannan Sadhasivam
2020-05-14 13:50               ` Kieran Bingham [this message]
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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