linux-kernel - Re: [PATCH RESEND v7 2/2] Add support for OV5647 sensor.

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Message-ID: <3d8368f8-0cae-934b-fc6a-0ead79db14aa@synopsys.com>
Date:   Thu, 9 Feb 2017 10:13:02 +0000
From:   Ramiro Oliveira <Ramiro.Oliveira@...opsys.com>
To:     Sakari Ailus <sakari.ailus@....fi>,
        Ramiro Oliveira <Ramiro.Oliveira@...opsys.com>
CC:     Sakari Ailus <sakari.ailus@...ux.intel.com>,
        <linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <CARLOS.PALMINHA@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Mark Rutland <mark.rutland@....com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        "Pavel Machek" <pavel@....cz>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Rob Herring <robh+dt@...nel.org>,
        Steve Longerbeam <slongerbeam@...il.com>
Subject: Re: [PATCH RESEND v7 2/2] Add support for OV5647 sensor.

Hi Sakari

On 2/9/2017 10:02 AM, Sakari Ailus wrote:
> Hi Ramiro,
> 
> On Wed, Feb 08, 2017 at 09:56:12AM +0000, Ramiro Oliveira wrote:
>> Hi Sakari
>>
>> On 2/7/2017 5:31 PM, Sakari Ailus wrote:
>>> Hi Ramiro,
>>>
>>> On Mon, Feb 06, 2017 at 11:38:28AM +0000, Ramiro Oliveira wrote:
>>> ...
>>>>>> +	ret = ov5647_write_array(sd, ov5647_640x480,
>>>>>> +					ARRAY_SIZE(ov5647_640x480));
>>>>>> +	if (ret < 0) {
>>>>>> +		dev_err(&client->dev, "write sensor_default_regs error\n");
>>>>>> +		return ret;
>>>>>> +	}
>>>>>> +
>>>>>> +	ov5647_set_virtual_channel(sd, 0);
>>>>>> +
>>>>>> +	ov5647_read(sd, 0x0100, &resetval);
>>>>>> +	if (!(resetval & 0x01)) {
>>>>>
>>>>> Can this ever happen? Streaming start is at the end of the register list.
>>>>>
>>>>
>>>> I'm not sure it can happen. It was just a safeguard, but I can remove it if you
>>>> think it's not necessary
>>>
>>> You're not reading back the other registers either, albeit I'd check that
>>> the I2C accesses actually succeed. Generally the return values are ignored.
>>>
>>
>> So you're recommending I perform a random I2C access after power on to check the
>> system, and discard the read value? Or just drop this piece of code entirely?
>>
> 
> I'm not. What I'm saying that you're mostly not checking whether I2C
> accesses succeed or not.
> 


I think I'm understanding what you're saying now. You want me to check more
often the return value from write/read functions?

That makes sense. I'll add more checks to the code

-- 
Best Regards

Ramiro Oliveira
Ramiro.Oliveira@...opsys.com