On 02/14/2014 03:44 PM, Antti Palosaari wrote:
> On 14.02.2014 16:30, Hans Verkuil wrote:
>> On 02/10/2014 05:17 PM, Antti Palosaari wrote:
>>> Modern silicon RF tuners used nowadays has many controllable gain
>>> stages on signal path. Usually, but not always, there is at least
>>> 3 gain stages. Also on some cases there could be multiple gain
>>> stages within the ones specified here. However, I think that having
>>> these three controllable gain stages offers enough fine-tuning for
>>> real use cases.
>>>
>>> 1) LNA gain. That is first gain just after antenna input.
>>> 2) Mixer gain. It is located quite middle of the signal path, where
>>> RF signal is down-converted to IF/BB.
>>> 3) IF gain. That is last gain in order to adjust output signal level
>>> to optimal level for receiving party (usually demodulator ADC).
>>>
>>> Each gain stage could be set rather often both manual or automatic
>>> (AGC) mode. Due to that add separate controls for controlling
>>> operation mode.
>>>
>>> Signed-off-by: Antti Palosaari <cr...@iki.fi>
>>> ---
>>> drivers/media/v4l2-core/v4l2-ctrls.c | 15 +++++++++++++++
>>> include/uapi/linux/v4l2-controls.h | 11 +++++++++++
>>> 2 files changed, 26 insertions(+)
>>>
>>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c
>>> b/drivers/media/v4l2-core/v4l2-ctrls.c
>>> index 6ff002b..d201f61 100644
>>> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
>>> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
>>> @@ -857,6 +857,14 @@ const char *v4l2_ctrl_get_name(u32 id)
>>> case V4L2_CID_FM_RX_CLASS: return "FM Radio Receiver
>>> Controls";
>>> case V4L2_CID_TUNE_DEEMPHASIS: return "De-Emphasis";
>>> case V4L2_CID_RDS_RECEPTION: return "RDS Reception";
>>> +
>>> + case V4L2_CID_RF_TUNER_CLASS: return "RF Tuner Controls";
>>> + case V4L2_CID_LNA_GAIN_AUTO: return "LNA Gain, Auto";
>>> + case V4L2_CID_LNA_GAIN: return "LNA Gain";
>>> + case V4L2_CID_MIXER_GAIN_AUTO: return "Mixer Gain, Auto";
>>> + case V4L2_CID_MIXER_GAIN: return "Mixer Gain";
>>> + case V4L2_CID_IF_GAIN_AUTO: return "IF Gain, Auto";
>>> + case V4L2_CID_IF_GAIN: return "IF Gain";
>>> default:
>>> return NULL;
>>> }
>>> @@ -906,6 +914,9 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum
>>> v4l2_ctrl_type *type,
>>> case V4L2_CID_WIDE_DYNAMIC_RANGE:
>>> case V4L2_CID_IMAGE_STABILIZATION:
>>> case V4L2_CID_RDS_RECEPTION:
>>> + case V4L2_CID_LNA_GAIN_AUTO:
>>> + case V4L2_CID_MIXER_GAIN_AUTO:
>>> + case V4L2_CID_IF_GAIN_AUTO:
>>> *type = V4L2_CTRL_TYPE_BOOLEAN;
>>> *min = 0;
>>> *max = *step = 1;
>>> @@ -991,6 +1002,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum
>>> v4l2_ctrl_type *type,
>>> case V4L2_CID_IMAGE_PROC_CLASS:
>>> case V4L2_CID_DV_CLASS:
>>> case V4L2_CID_FM_RX_CLASS:
>>> + case V4L2_CID_RF_TUNER_CLASS:
>>> *type = V4L2_CTRL_TYPE_CTRL_CLASS;
>>> /* You can neither read not write these */
>>> *flags |= V4L2_CTRL_FLAG_READ_ONLY | V4L2_CTRL_FLAG_WRITE_ONLY;
>>> @@ -1063,6 +1075,9 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum
>>> v4l2_ctrl_type *type,
>>> case V4L2_CID_PILOT_TONE_FREQUENCY:
>>> case V4L2_CID_TUNE_POWER_LEVEL:
>>> case V4L2_CID_TUNE_ANTENNA_CAPACITOR:
>>> + case V4L2_CID_LNA_GAIN:
>>> + case V4L2_CID_MIXER_GAIN:
>>> + case V4L2_CID_IF_GAIN:
>>> *flags |= V4L2_CTRL_FLAG_SLIDER;
>>> break;
>>> case V4L2_CID_PAN_RELATIVE:
>>> diff --git a/include/uapi/linux/v4l2-controls.h
>>> b/include/uapi/linux/v4l2-controls.h
>>> index 2cbe605..076fa34 100644
>>> --- a/include/uapi/linux/v4l2-controls.h
>>> +++ b/include/uapi/linux/v4l2-controls.h
>>> @@ -60,6 +60,7 @@
>>> #define V4L2_CTRL_CLASS_IMAGE_PROC 0x009f0000 /* Image
>>> processing controls */
>>> #define V4L2_CTRL_CLASS_DV 0x00a00000 /* Digital
>>> Video controls */
>>> #define V4L2_CTRL_CLASS_FM_RX 0x00a10000 /* FM Receiver
>>> controls */
>>> +#define V4L2_CTRL_CLASS_RF_TUNER 0x00a20000 /* RF tuner controls */
>>>
>>> /* User-class control IDs */
>>>
>>> @@ -895,4 +896,14 @@ enum v4l2_deemphasis {
>>>
>>> #define V4L2_CID_RDS_RECEPTION
>>> (V4L2_CID_FM_RX_CLASS_BASE + 2)
>>>
>>> +#define V4L2_CID_RF_TUNER_CLASS_BASE
>>> (V4L2_CTRL_CLASS_RF_TUNER | 0x900)
>>> +#define V4L2_CID_RF_TUNER_CLASS
>>> (V4L2_CTRL_CLASS_RF_TUNER | 1)
>>> +
>>> +#define V4L2_CID_LNA_GAIN_AUTO
>>> (V4L2_CID_RF_TUNER_CLASS_BASE + 1)
>>> +#define V4L2_CID_LNA_GAIN (V4L2_CID_RF_TUNER_CLASS_BASE +
>>> 2)
>>> +#define V4L2_CID_MIXER_GAIN_AUTO (V4L2_CID_RF_TUNER_CLASS_BASE +
>>> 3)
>>> +#define V4L2_CID_MIXER_GAIN
>>> (V4L2_CID_RF_TUNER_CLASS_BASE + 4)
>>> +#define V4L2_CID_IF_GAIN_AUTO
>>> (V4L2_CID_RF_TUNER_CLASS_BASE + 5)
>>> +#define V4L2_CID_IF_GAIN (V4L2_CID_RF_TUNER_CLASS_BASE +
>>> 6)
>>
>> I would prefer to give these control defines a prefix:
>>
>> V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO (or possibly V4L2_CID_RF_TNR_...)
>>
>> 'MIXER_GAIN' by itself does not make it clear it relates to a tuner, it
>> might just as well refer to audio mixing or video mixing.
>>
>> Thinking this over I am wondering whether these controls might not fit
>> just as well with the FM_RX class. Yeah, I know, the 'FM' part is a bit
>> unfortunate in that context, but it is about radio receivers as well.
>>
>> Unless there is a good reason to keep these controls in their own class?
>
> Those controls in FM RX class are way layer or two upper level. Controls
> in FM RX are from the demulation whilst the controls I added to RF tuner
> are from RF tuner and are suitable for every device having RF tuner,
> like radio, television, GPS, etc.
Fair enough. It would be good though if this could be clarified in the
description
of this control class in DocBook. It's fairly specialized stuff, so some
background
information or perhaps a link to wikipedia (if there is a suitable article
there)
can be helpful.
Regards,
Hans
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