linux-kernel - Re: [PATCH v2 12/12] ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver

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Message-ID: <5ba6ada9-c8a6-fa66-b8d6-5769b7bcdfea@gmail.com>
Date:   Mon, 21 Dec 2020 10:52:52 +0000
From:   Daniel Scally <djrscally@...il.com>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        devel@...ica.org, "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Yong Zhi <yong.zhi@...el.com>,
        Bingbu Cao <bingbu.cao@...el.com>,
        Tian Shu Qiu <tian.shu.qiu@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Robert Moore <robert.moore@...el.com>,
        Erik Kaneda <erik.kaneda@...el.com>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Jacopo Mondi <jacopo+renesas@...ndi.org>,
        kieran.bingham+renesas@...asonboard.com,
        Linus Walleij <linus.walleij@...aro.org>,
        "Krogerus, Heikki" <heikki.krogerus@...ux.intel.com>,
        Tsuchiya Yuto <kitakar@...il.com>, jorhand@...ux.microsoft.com
Subject: Re: [PATCH v2 12/12] ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver


On 21/12/2020 10:21, Sakari Ailus wrote:
> Hi Daniel, Andy,
>
> On Sat, Dec 19, 2020 at 11:48:51PM +0000, Daniel Scally wrote:
>> On 19/12/2020 18:52, Andy Shevchenko wrote:
>>> On Sat, Dec 19, 2020 at 2:25 AM Daniel Scally <djrscally@...il.com> wrote:
>>>> On 18/12/2020 21:17, Andy Shevchenko wrote:
>>>>> On Thu, Dec 17, 2020 at 11:43:37PM +0000, Daniel Scally wrote:
>>> ...
>>>
>>>>>> +    sensor->ep_properties[0] = PROPERTY_ENTRY_U32(sensor->prop_names.bus_type, 4);
>>>>> Does 4 has any meaning that can be described by #define ?
>>>> It's V4L2_FWNODE_BUS_TYPE_CSI2_DPHY:
>>>>
>>>> https://elixir.bootlin.com/linux/latest/source/drivers/media/v4l2-core/v4l2-fwnode.c#L36
>>>>
>>>> That enum's not in an accessible header, but I can define it in this
>>>> module's header
>>> Maybe you can do a preparatory patch to make it visible to v4l2
>>> drivers? (Like moving to one of v4l2 headers)
>> Sure ok, guess media/v4l2-fwnode.h makes the most sense.
> Yes, please.
Done for the next version
>
>>> ...
>>>
>>>>>> +                    if (bridge->n_sensors >= CIO2_NUM_PORTS) {
>>>>>> +                            dev_warn(&cio2->dev, "Exceeded available CIO2 ports\n");
>>>>>> +                            /* overflow i so outer loop ceases */
>>>>>> +                            i = ARRAY_SIZE(cio2_supported_sensors);
>>>>>> +                            break;
>>>>> Why not to create a new label below and assign ret here with probably comment
>>>>> why it's not an error?
>>>> Sure, I can do that, but since it wouldn't need any cleanup I could also
>>>> just return 0 here as Laurent suggest (but with a comment explaining why
>>>> that's ok as you say) - do you have a preference?
>>> While it's a good suggestion it will bring a bit of inconsistency into
>>> approach. Everywhere else in the function you are using the goto
>>> approach.
>>> So yes, I have a preference.
>> No problem
> Laurent also commented on the return code.
>
> I might just handle this as an error. The earlier ports are fine, but
> there's also a problem with the data here. It'd be easier to spot that this
> way, and we can change this in the future if need be.


You mean just raise an error with dev_err()? Or fail the probe and
unwind the 4 sensors that were already connected successfully? I'm fine
with that if so - we have no in scope devices where that will be a
problem at the moment.