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Date: Fri, 13 Dec 2013 14:58:53 +0100
From: Hans Verkuil <hverkuil@xs4all.nl>
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To: Antti Palosaari <crope@iki.fi>
CC: linux-media@vger.kernel.org,
	Mauro Carvalho Chehab <m.chehab@samsung.com>
Subject: Re: [PATCH RFC 3/4] v4l: add new tuner types for SDR
References: <1386806043-5331-1-git-send-email-crope@iki.fi> <1386806043-5331-4-git-send-email-crope@iki.fi> <52A96ABF.50905@xs4all.nl> <52A9EE96.4050306@iki.fi>
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On 12/12/2013 06:12 PM, Antti Palosaari wrote:
> On 12.12.2013 09:50, Hans Verkuil wrote:
>> On 12/12/2013 12:54 AM, Antti Palosaari wrote:
>>> Define tuner types V4L2_TUNER_ADC and V4L2_TUNER_SDR for SDR usage.
>>>
>>> ADC is used for setting sampling rate (sampling frequency) to SDR
>>> device.
>>>
>>> Another tuner type, SDR, is possible RF tuner. Is is used to
>>> down-convert RF frequency to range ADC could sample. It is optional
>>> for SDR device.
>>>
>>> Also add checks to VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY and
>>> VIDIOC_ENUM_FREQ_BANDS only allow these two tuner types when device
>>> type is SDR (VFL_TYPE_SDR).
>>
>> Shouldn't you also adapt s_hw_freq_seek?
> 
> nope! I don't see how SDR could do hardware seek as demodulator is 
> needed to make decision if radio channel is valid or not. On SDR 
> receiver that demodulator is implemented by application software, DSP, 
> thus name software defined radio.
> 
> Maybe it could be mapped to signal strength measurement, but it is 
> another story to think.

Fair enough, but in that case I would add:

	/* s_hw_freq_seek is not supported for SDR for now */
	if (vfd->vfl_type == VFL_TYPE_SDR)
		return -EINVAL;

at the beginning of v4l_s_hw_freq_seek().

Regards,

	Hans