[asterisk-bugs] [JIRA] (ASTERISK-22429) [patch] - chan_dahdi allows for updating both hw and sw gains, but dahdi show channel doesn't reflect changes

[Richard Mudgett (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-22429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=210866#comment-210866 ] 

Richard Mudgett commented on ASTERISK-22429:
--------------------------------------------

{quote}
Since it isn't possible to query the hwgain values - isn't it better to rip out the hwgain stuff completely rather than to just try and document the problem away? Or alternatively, to finish it (which shouldn't be hard - other than querying the initial hwgain values in the case where no hwgain is set) properly?
{quote}

I can only see ripping it out on trunk and not on any released branches.  However, ripping it out will not save much since it is only the CLI command that would be removed and it does no harm leaving it in.  Someone may actually have a use for it that I cannot see.  "Finishing" the feature will actually *cause* harm because it would then always override any modprobe setting.

{quote}
Is there any advantage (even theoretically) to use hwgain over swgain (eg, clarity of signal, improved sampling etc ...),
{quote}

I don't think there is any advantage other than some small savings in CPU time.  Otherwise, it is a hit or miss feature depending upon hardware support.
                
> [patch] - chan_dahdi allows for updating both hw and sw gains, but dahdi show channel doesn't reflect changes
> -------------------------------------------------------------------------------------------------------------
>
>                 Key: ASTERISK-22429
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-22429
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Channels/chan_dahdi
>    Affects Versions: 11.5.0
>            Reporter: Jaco Kroon
>            Assignee: Richard Mudgett
>            Severity: Minor
>         Attachments: asterisk-11.5.0-dahdi_gain_display.diff, jira_asterisk_22429_v11.patch, jira_asterisk_22429_v1.8.patch
>
>
> I think some output explains it best:
> # asterisk -Rx "dahdi show channel 3" | grep Gains
> Gains (RX/TX): 8.00/6.00
> # asterisk -rx "dahdi set swgain rx 3 4.0"
> software rx gain set to 4.0 on channel 3
> # asterisk -Rx "dahdi show channel 3" | grep Gains
> Gains (RX/TX): 8.00/6.00
> So in spite of the gain having being modified the change is not reflected.  There is also no indication whether the displayed gains is the hw or sw gains.
> I've written a small patch to rectify the situation and improve it somewhat:
> # asterisk -Rx "dahdi show channel 3" | grep Gains
> SW Gains (RX/TX): 8.00/6.00
> HW Gains (RX/TX): 0.00/0.00
> # asterisk -rx "dahdi set swgain rx 3 4.0"
> software rx gain set to 4.0 on channel 3
> # asterisk -Rx "dahdi show channel 3" | grep Gains
> SW Gains (RX/TX): 4.00/6.00
> HW Gains (RX/TX): 0.00/0.00
> There is a secondary (and actually more significant) problem here:
> The hw gains are not initialized during startup/reload at all (at least, not as far as I can tell).  And if they're already set during reload/restart the only way that I can see to get them back to some pre-configured value is to explicitly reset them using "dahdi set hwgain".  This patch assumes that they are zeroed during startup/reload (which can be false).

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.asterisk.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira