lkml.org 
[lkml]   [2012]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH 3/3] wl128x: Add sysfs based support for FM features
    On Fri, Mar 2, 2012 at 3:22 AM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
    > On Wednesday, February 29, 2012 18:19:27 halli manjunatha wrote:
    >> On Wed, Feb 29, 2012 at 5:25 AM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
    >> > On Tuesday, February 28, 2012 23:52:21 halli manjunatha wrote:
    >> >> On Tue, Feb 28, 2012 at 4:05 AM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
    >> >> > On Monday, February 27, 2012 17:29:18 halli manjunatha wrote:
    >> >> >> Hi Hans,
    >> >> >>
    >> >> >> Agreed I don't mind to create new controls for below things
    >> >> >>
    >> >> >> 1) FM RX Band selection (US/Europe, Japan and Russian bands)
    >> >> >> 2) FM RX RDS AF turn ON/OFF
    >> >> >> 3) FM RX RSSI level set/get
    >> >> >> 4) FM TX Alternate Frequency set/get
    >> >> >> 5) FM RX De-Emphasis mode set/get
    >> >> >>
    >> >> >> However, previously you have suggested me to hide few controls (like
    >> >> >> band selection) from the user but few of our application wanted
    >> >> >> controls like above and that is why I have created the sysfs entries.
    >> >> >>
    >> >> >> Please suggest me how can I move forward with new controls or with sysfs?
    >> >> >
    >> >> > The first question is which of these controls are general to FM receivers or
    >> >> > transmitters, and which are specific to this chipset. The chipset specific
    >> >> > controls should be private controls (look at V4L2_CID_MPEG_CX2341X_BASE in
    >> >> > videodev2.h how those are defined). The others should be defined as new
    >> >> > controls of the FM_TX class or the FM_RX class. The FM_RX class should be
    >> >> > defined as a new class as it doesn't exist at the moment. Don't forget to
    >> >> > document these controls clearly.
    >> >> >
    >> >> > With regards to the band selection: I remember that there was a discussion,
    >> >> > but not the details. Do you have a link to that discussion? I can't find it
    >> >> > (at least not quickly :-) ).
    >> >>
    >> >> Below features are generic to all FM receivers so we can add new CID's
    >> >> for below features
    >> >> 1) FM RX RDS AF turn ON/OFF
    >> >> 2) FM TX Alternate Frequency set/get
    >> >>
    >> >> About other 3 features its different issue,
    >> >>     1) FM RX Band selection (US/Europe, Japan and Russian bands)
    >> >>     2) FM RX RSSI level set/get
    >> >>     3) FM RX De-Emphasis mode set/get
    >> >>
    >> >> All these 3 features are generic to any FM receiver, only question is
    >> >> does all FM receivers wants to expose these controls to application
    >> >> writer?
    >> >
    >> > Good question, and there is no good answer at the moment. See e.g. this
    >> > IRC discussion:
    >> >
    >> > http://www.spinics.net/lists/linux-media/msg44023.html
    >> >
    >> > In the absence of a good solution to this problem I am inclined to make
    >> > these controls driver specific but marked experimental. The experimental
    >> > tag allows us to eventually make it a generic control without too much
    >> > hassle.
    >>
    >> Agreed, I will make them driver specific and mark them as experimental.
    >>
    >> >
    >> >> Example Band selection, every FM receiver at the minimum supports both
    >> >> Europe and Japan band, now the question is should we add a CID to
    >> >> switch between these two bands?
    >> >
    >> > If we decide to add a band selection control, then that would be a menu
    >> > control (since there are up to three bands) and it would only be implemented
    >> > by drivers that need it.
    >> >
    >> > What I am still not clear on is *why* you would want this control. What
    >> > is the reason your customers want this? What does it allow you to do that
    >> > can't be done today?
    >>
    >> There are 2 reasons for this,
    >>
    >> First, our chip supports weather band, unlike other bands (Europe,
    >> Japan and Russian) user may wants to
    >> switch to weather band and wants to listen to weather report and again
    >> switches back to normal band.
    >
    > OK, that makes sense. Are the RX and TX independent with regards to
    > band selection?

    Yes - RX and TX are independent of band selection

    > Make sure that when the band is changed the rangelow and rangehigh values
    > are also changed. If the current frequency is out of that range, then the
    > frequency should be clamped to the closest value frequency. Although an
    > alternative strategy might be to remember the last used frequency for each
    > band. That might make more sense in the case of switching between a normal
    > band and the weather band. We need to define and document which strategy
    > should be used here.

    As of now when I switch to new band I just set the frequency to lowest
    of the new band.
    In this way user can seek and tune to what ever channel he wants.

    > BTW, is the receiver for the weather band implemented as a separate receiver?
    > I read that some devices can listen to the normal band and interrupt that
    > when a weather report is broadcast on the weather band. That implies two
    > receivers and it would require a rethink.
    >
    > Also, is this feature really implemented as separate frequency ranges in
    > hardware? Or is the receiver able to receive on the whole range of frequencies
    > from 65.8 (OIRT) to approx. 165 (weather band range)?

    Our chip wont have 2 receivers, it has only 1 receiver which can
    receive on whole frequency range from 65 MHz to 165 MHz.

    > Is the datasheet of this device available somewhere?

    Sorry our newest chipset supports this feature so yet now we don't
    have any datasheet available on net.

    >
    >> Second,  for FM TX, our chip supports band selection for FM
    >> transmitter, so if the same phone is used in different
    >> regions of world then user can switch to the actual band and start
    >> transmitting by choosing a blank frequency in that band.
    >
    > Isn't this something that can be equally easily done in userspace?

    you wants me to do this from driver itself without hinting the
    application about the band ?

    >
    > Regards,
    >
    >        Hans
    > --
    > To unsubscribe from this list: send the line "unsubscribe linux-media" in
    > the body of a message to majordomo@vger.kernel.org
    > More majordomo info at  http://vger.kernel.org/majordomo-info.html



    --
    Regards
    Halli
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2012-03-05 17:27    [W:0.037 / U:30.108 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site