On Wed 11 July 2012 20:37:14 Hans de Goede wrote: > Hi Hans, > > On 07/11/2012 08:01 PM, Hans Verkuil wrote: > > Hi Hans, > > > > Thanks for the patch. > > > > I've CC-ed Halli as well. > > > > On Wed July 11 2012 17:47:34 Hans de Goede wrote: > >> To allow apps to limit a hw-freq-seek to a specific band, for further > >> info see the documentation this patch adds for these new fields. > >> > >> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > >> --- > >> .../DocBook/media/v4l/vidioc-s-hw-freq-seek.xml | 44 ++++++++++++++++---- > >> include/linux/videodev2.h | 5 ++- > >> 2 files changed, 40 insertions(+), 9 deletions(-) > >> > >> diff --git a/Documentation/DocBook/media/v4l/vidioc-s-hw-freq-seek.xml b/Documentation/DocBook/media/v4l/vidioc-s-hw-freq-seek.xml > >> index f4db44d..50dc9f8 100644 > >> --- a/Documentation/DocBook/media/v4l/vidioc-s-hw-freq-seek.xml > >> +++ b/Documentation/DocBook/media/v4l/vidioc-s-hw-freq-seek.xml > >> @@ -52,11 +52,21 @@ > >> <para>Start a hardware frequency seek from the current frequency. > >> To do this applications initialize the <structfield>tuner</structfield>, > >> <structfield>type</structfield>, <structfield>seek_upward</structfield>, > >> -<structfield>spacing</structfield> and > >> -<structfield>wrap_around</structfield> fields, and zero out the > >> -<structfield>reserved</structfield> array of a &v4l2-hw-freq-seek; and > >> -call the <constant>VIDIOC_S_HW_FREQ_SEEK</constant> ioctl with a pointer > >> -to this structure.</para> > >> +<structfield>wrap_around</structfield>, <structfield>spacing</structfield>, > >> +<structfield>rangelow</structfield> and <structfield>rangehigh</structfield> > >> +fields, and zero out the <structfield>reserved</structfield> array of a > >> +&v4l2-hw-freq-seek; and call the <constant>VIDIOC_S_HW_FREQ_SEEK</constant> > >> +ioctl with a pointer to this structure.</para> > >> + > >> + <para>The <structfield>rangelow</structfield> and > >> +<structfield>rangehigh</structfield> fields can be set to a non-zero value to > >> +tell the driver to search a specific band. If the &v4l2-tuner; > >> +<structfield>capability</structfield> field has the > >> +<constant>V4L2_TUNER_CAP_HWSEEK_PROG_LIM</constant> flag set, these values > >> +must fall within one of the bands returned by &VIDIOC-ENUM-FREQ-BANDS;. If > >> +the <constant>V4L2_TUNER_CAP_HWSEEK_PROG_LIM</constant> flag is not set, > >> +then these values must exactly match those of one of the bands returned by > >> +&VIDIOC-ENUM-FREQ-BANDS;.</para> > > > > OK, I have some questions here: > > > > 1) If you have a multiband tuner, what should happen if both low and high are > > zero? Currently it is undefined, other than that the seek should start from > > the current frequency until it reaches some limit. > > That would be driver specific, we could add the same "If rangelow/high is zero > a reasonable default value is used." language as used for the spacing. For > example for the si470x if both are zero I simply switch to the "Japan wide" > band which covers all frequencies handled by the other bands, but if there > is no such covers all ranges band, then the logical thing todo would just keep > the band as is (so as determined by the last s_freq). > > > Halli, what does your hardware do? In particular, is the hwseek limited by the > > US/Europe or Japan band range or can it do the full range? If I'm not mistaken > > it is the former, right? > > > > If it is the former, then you need to explicitly set low + high to ensure that > > the hwseek uses the correct range because the driver can't guess which of the > > overlapping bands to use. > > > > 2) What happens if the current frequency is outside the low/high range? The > > hwseek spec says that the seek starts from the current frequency, so that might > > mean that hwseek returns -ERANGE in this case. > > What the si470x code currently does is just clamp the frequency to the new > range before seeking, but -ERANGE works for me too. Clamping is a better idea IMHO as long as it is documented. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
