Re: [PATCH 2/5] media: i2c: max2175: Add MAX2175 support

[Hans Verkuil <hverkuil@xs4all.nl>]

On 11/11/2016 02:48 PM, Laurent Pinchart wrote:
> Hi Hans,
> 
> On Friday 11 Nov 2016 14:21:22 Hans Verkuil wrote:
>> On 11/09/2016 04:44 PM, Ramesh Shanmugasundaram wrote:
>>> This patch adds driver support for MAX2175 chip. This is Maxim
>>> Integrated's RF to Bits tuner front end chip designed for software-defined
>>> radio solutions. This driver exposes the tuner as a sub-device instance
>>> with standard and custom controls to configure the device.
>>>
>>> Signed-off-by: Ramesh Shanmugasundaram
>>> <ramesh.shanmugasundaram@bp.renesas.com> ---
>>>
>>>  .../devicetree/bindings/media/i2c/max2175.txt      |   61 +
>>>  drivers/media/i2c/Kconfig                          |    4 +
>>>  drivers/media/i2c/Makefile                         |    2 +
>>>  drivers/media/i2c/max2175/Kconfig                  |    8 +
>>>  drivers/media/i2c/max2175/Makefile                 |    4 +
>>>  drivers/media/i2c/max2175/max2175.c                | 1558 +++++++++++++++
>>>  drivers/media/i2c/max2175/max2175.h                |  108 ++
>>>  7 files changed, 1745 insertions(+)
>>>  create mode 100644
>>>  Documentation/devicetree/bindings/media/i2c/max2175.txt
>>>  create mode 100644 drivers/media/i2c/max2175/Kconfig
>>>  create mode 100644 drivers/media/i2c/max2175/Makefile
>>>  create mode 100644 drivers/media/i2c/max2175/max2175.c
>>>  create mode 100644 drivers/media/i2c/max2175/max2175.h
>>
>> <snip>
>>
>>> diff --git a/drivers/media/i2c/max2175/max2175.c
>>> b/drivers/media/i2c/max2175/max2175.c new file mode 100644
>>> index 0000000..ec45b52
>>> --- /dev/null
>>> +++ b/drivers/media/i2c/max2175/max2175.c
>>> @@ -0,0 +1,1558 @@
>>
>> <snip>
>>
>>> +/* Read/Write bit(s) on top of regmap */
>>> +static int max2175_read(struct max2175 *ctx, u8 idx, u8 *val)
>>> +{
>>> +	u32 regval;
>>> +	int ret = regmap_read(ctx->regmap, idx, &regval);
>>> +
>>> +	if (ret)
>>> +		v4l2_err(ctx->client, "read ret(%d): idx 0x%02x\n", ret, idx);
> 
> By the way, I think I've seen a proposal to get rid of v4l2_err() in favour of 
> dev_err(), was I dreaming or should this patch use dev_err() already ?

I haven't seen anything, but I may have missed it. I haven't been on top of the
mailinglist lately. I'm fine with both.

> 
>>> +
>>> +	*val = regval;
>>
>> Does regmap_read initialize regval even if it returns an error? If not,
>> then I would initialize regval to 0 to prevent *val being uninitialized.
> 
> Better than that the error should be propagated to the caller and handled.
> 
>>> +	return ret;
>>> +}
> 
> [snip]
> 
>>> +static int max2175_band_from_freq(u32 freq)
>>> +{
>>> +	if (freq >= 144000 && freq <= 26100000)
>>> +		return MAX2175_BAND_AM;
>>> +	else if (freq >= 65000000 && freq <= 108000000)
>>> +		return MAX2175_BAND_FM;
>>> +	else
>>
>> No need for these 'else' keywords.
> 
> Indeed by in my opinion they improve readability :-)
> 
>>> +		return MAX2175_BAND_VHF;
>>> +}
> 
> [snip]
> 
>>> +static const struct v4l2_ctrl_config max2175_na_rx_mode = {
>>> +	.ops = &max2175_ctrl_ops,
>>> +	.id = V4L2_CID_MAX2175_RX_MODE,
>>> +	.name = "RX MODE",
>>> +	.type = V4L2_CTRL_TYPE_MENU,
>>> +	.max = ARRAY_SIZE(max2175_ctrl_na_rx_modes) - 1,
>>> +	.def = 0,
>>> +	.qmenu = max2175_ctrl_na_rx_modes,
>>> +};
>>
>> Please document all these controls better. This is part of the public API,
>> so you need to give more information what this means exactly.
> 
> Should that go to Documentation/media/v4l-drivers/ ? If so "[PATCH v4 3/4] 
> v4l: Add Renesas R-Car FDP1 Driver" can be used as an example.

I think that's the preferred place going forward. But a comment should be
added here pointing to that file so there is a better chance of keeping
the doc and code in sync.

> 
> [snip]
> 

	Hans