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

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Message-ID: <e86fc26d-8c2f-c8a6-fc2e-ec612fd5d158@gmail.com>
Date:   Sat, 19 Dec 2020 23:48:51 +0000
From:   Daniel Scally <djrscally@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     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>,
        Sakari Ailus <sakari.ailus@...ux.intel.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 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.

> ...
> 
>>>> +                    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

>>>> +                    }
> 
> ...
> 
>>>> +                    ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",
>>>> +                                                       &sensor->ssdb,
>>>> +                                                       sizeof(sensor->ssdb));
>>>> +                    if (ret < 0)
>>>
>>> if (ret) (because positive case can be returned just by next conditional).
>>
>> cio2_bridge_read_acpi_buffer() returns the buffer length on success at
>> the moment, but I can change it to return 0 and have this be if (ret)
> 
> Please correct this somehow, because the next failure returns it
> instead of error...

Ah! Good spot - thank you. I will fix that yes.

>>>> +                            goto err_put_adev;
>>>> +
>>>> +                    if (sensor->ssdb.lanes > 4) {
>>>> +                            dev_err(&adev->dev,
>>>> +                                    "Number of lanes in SSDB is invalid\n");
> 
> ...I'm even thinking that you have to assign ret here to something meaningful.

Yeah I agree, I will do this too.

>>>> +                            goto err_put_adev;
>>>> +                    }
>