On Sun April 21 2013 21:00:33 Mauro Carvalho Chehab wrote:
> As discussed at:
>
> http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructure/63123
>
> SDR radio require some other things at to set. VIDIOC_[G|S]_TUNER
> is currently not enough.
>
> I proposed there to create an extra ioctl for it, but the thing
> is that VIDIOC_[G|S]_TUNER is meant to set what's needed to configure
> the tuner. So, add there the missing bits to:
> - set/get the tuner sampling rate;
> - set/get the tuner low pass bandwidth filter;
> - get the tuner IF.
>
> VIDIOC_[G|S]_TUNER already provides:
> - tuner input switch;
> - tuner input name;
> - tuner capability flags;
> - tuner range;
> - signal strength;
> - afc.
>
> There are still 3 u32 reserved fields there that may be used for
> SDR in the future, and may be neded at the final version.
>
> For example, it may make sense to add a SDR flag with:
> - bandwidth inversion flag;
> - tuner PLL lock flag (or reuse signal strength for that).
>
> It also makes sense to add sample_rate range there.
>
> Signed-off-by: Mauro Carvalho Chehab <mche...@redhat.com>
> ---
> Documentation/DocBook/media/v4l/vidioc-g-tuner.xml | 30 ++++++++++++++---
> drivers/media/tuners/tuner-xc2028.c | 2 ++
> include/uapi/linux/videodev2.h | 38
> ++++++++++++++++++++--
> 3 files changed, 63 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/DocBook/media/v4l/vidioc-g-tuner.xml
> b/Documentation/DocBook/media/v4l/vidioc-g-tuner.xml
> index 6cc8201..b8a3bcf 100644
> --- a/Documentation/DocBook/media/v4l/vidioc-g-tuner.xml
> +++ b/Documentation/DocBook/media/v4l/vidioc-g-tuner.xml
> @@ -200,9 +200,10 @@ audio</entry>
> <constant>_SAP</constant> flag is cleared in the
> <structfield>capability</structfield> field, the corresponding
> <constant>V4L2_TUNER_SUB_</constant> flag must not be set
> -here.</para><para>This field is valid only if this is the tuner of the
> +here.</para>
> +<para>This field is valid only for if this is the tuner of the
> current video input, or when the structure refers to a radio
> -tuner.</para></entry>
> +tuner. This field is not used by SDR tuners.</para></entry>
> </row>
> <row>
> <entry>__u32</entry>
> @@ -216,7 +217,7 @@ unless the requested mode is invalid or unsupported. See
> <xref
> the selected and received audio programs do not
> match.</para><para>Currently this is the only field of struct
> <structname>v4l2_tuner</structname> applications can
> -change.</para></entry>
> +change. This field is not used by SDR tuners.</para></entry>
> </row>
> <row>
> <entry>__u32</entry>
> @@ -234,7 +235,28 @@ settles at zero, &ie; range is what? --></entry>
> </row>
> <row>
> <entry>__u32</entry>
> - <entry><structfield>reserved</structfield>[4]</entry>
> + <entry><structfield>sample_rate</structfield></entry>
> + <entry spanname="hspan">Sampling rate used by a SDR tuner, in Hz.
> + This value is valid only for SDR tuners.</entry>
Are frequencies >4GHz ever likely for SDR? If so, then a u64 might be needed
here.
> + </row>
> + <row>
> + <entry>__u32</entry>
> + <entry><structfield>bandwidth</structfield></entry>
> + <entry spanname="hspan">Bandwidth allowed by the SDR tuner
> + low-pass saw filter, in Hz. This value is valid only for
> + SDR tuners.</entry>
> + </row>
> + <row>
> + <entry>__u32</entry>
> + <entry><structfield>int_freq</structfield></entry>
> + <entry spanname="hspan">Intermediate Frequency (IF) used by
> + the tuner, in Hz. This value is valid only for
> + <constant>VIDIOC_G_TUNER</constant>, and it is valid only
> + on SDR tuners.</entry>
> + </row>
> + <row>
> + <entry>__u32</entry>
> + <entry><structfield>reserved</structfield>[3]</entry>
It's not clear from this doc that this is an anonymous union. See e.g. the
decoder_cmd documentation how that is done elsewhere.
> <entry spanname="hspan">Reserved for future extensions. Drivers and
> applications must set the array to zero.</entry>
> </row>
> diff --git a/drivers/media/tuners/tuner-xc2028.c
> b/drivers/media/tuners/tuner-xc2028.c
> index 878d2c4..c61163f 100644
> --- a/drivers/media/tuners/tuner-xc2028.c
> +++ b/drivers/media/tuners/tuner-xc2028.c
> @@ -1020,6 +1020,8 @@ static int generic_set_freq(struct dvb_frontend *fe,
> u32 freq /* in HZ */,
> * Maybe this might also be needed for DTV.
> */
> switch (new_type) {
> + default: /* SDR currently not supported */
> + goto ret;
> case V4L2_TUNER_ANALOG_TV:
> rc = send_seq(priv, {0x00, 0x00});
>
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 974c49d..c002030 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -160,6 +160,22 @@ enum v4l2_tuner_type {
> V4L2_TUNER_RADIO = 1,
> V4L2_TUNER_ANALOG_TV = 2,
> V4L2_TUNER_DIGITAL_TV = 3,
> +/*
> + * Even not decoding the signal, SDR tuners may require to adjust IF,
> + * low pass filters, center frequency, etc based on the signal envelope,
> + * and its bandwidth. While we might be using here the V4L2_STD_*
> + * types, plus DVB delsys, that doesn't seem to be the better thing to
delsys? Is that a typo or is that DVB terminology that I am unfamiliar with?
s/better/best/
> + * do, as:
> + * 1) it would require 64 bits for V4L2 std + 32 bits for DVB std;
> + * 2) non-TV types of envelopes won't work.
> + *
> + * So, add a separate enum to describe the possible types of SDR envelopes.
> + */
> + V4L2_TUNER_SDR_RADIO = 10, /* Generic non-optimized Radio range */
I'd go with 0x10, just in case we ever need to do some bitmask magic.
> + V4L2_TUNER_SDR_ATV, /* Optimize for Analog TV */
> + V4L2_TUNER_SDR_DTV_ATSC, /* Optimize for Digital TV, ATSC */
> + V4L2_TUNER_SDR_DTV_DVBT, /* Optimize for Digital TV, DVB-T */
> + V4L2_TUNER_SDR_DTV_ISDBT, /* Optimize for Digital TV, ISDB-T */
> };
>
> enum v4l2_memory {
> @@ -1291,6 +1307,7 @@ struct v4l2_querymenu {
> /*
> * T U N I N G
> */
> +
> struct v4l2_tuner {
> __u32 index;
> __u8 name[32];
> @@ -1298,11 +1315,26 @@ struct v4l2_tuner {
> __u32 capability;
> __u32 rangelow;
> __u32 rangehigh;
> - __u32 rxsubchans;
> - __u32 audmode;
> +
> + union {
> + /* non-SDR tuners */
> + struct {
> + __u32 rxsubchans;
> + __u32 audmode;
> + };
> + /* SDR tuners - audio demod data makes no sense here */
> + struct {
> + __u32 sample_rate; /* Sample rate, in Hz */
> + __u32 bandwidth; /* Bandwidth, in Hz */
> + };
> + };
> +
> __s32 signal;
> __s32 afc;
> - __u32 reserved[4];
> +
> + __u32 int_freq; /* Read Only - IF used, in Hz */
> + /* non-SDR tuners */
> + __u32 reserved[3];
> };
Before we finalize this API we must be really certain that all the fields we
need for the SDR tuner can actually fit in this struct. If we are not certain,
then a G/S_SDR_TUNER ioctl might be more appropriate.
Regards,
Hans
>
> struct v4l2_modulator {
>
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