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

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Ramiro,

On Thu, Feb 09, 2017 at 10:13:02AM +0000, Ramiro Oliveira wrote:
> 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

Please do. That's generally a better approach with I2C than reading back
register values.  :-)

-- 
Sakari Ailus
sakari.ailus@linux.intel.com