Re: [gpsd-dev] [PATCH] gpsd: Don't gratuitously switch drivers, if we already have a driver that matches the packet type

[Andy Walls]

Same bug reported in April of 2012:

http://lists.nongnu.org/archive/html/gpsd-dev/2012-04/msg00023.html

Regards,
Andy

On Wed, 2013-08-07 at 18:09 -0400, Andy Walls wrote:
> Don't gratuitously switch drivers if we already have a driver that
> matches the packet type.
> 
> Without this patch gpsd switches away driver that supports the NMEA
> packet type and switches to the "Generic NMEA" driver.  
> 
> I have tested this patch with my device only.
> 
> I discovered this problem while integrating a Trimble Condor (MT-3329?)
> based device into the MT-3301 driver.
> 
> See also:
> http://savannah.nongnu.org/bugs/?38454
> 
> There is also another list posting that I can't find right now, with
> someone with a similar problem.
> 
> Regards,
> Andy
> 
> diff --git a/libgpsd_core.c b/libgpsd_core.c
> index e806328..b0254ed 100644
> --- a/libgpsd_core.c
> +++ b/libgpsd_core.c
> @@ -954,11 +954,18 @@ gps_mask_t gpsd_poll(struct gps_device_t *session)
>           /* FALL THROUGH */
>       } else if (session->packet.type > COMMENT_PACKET) {
>           first_sync = (session->device_type == NULL);
> -         for (dp = gpsd_drivers; *dp; dp++)
> -             if (session->packet.type == (*dp)->packet_type) {
> -                 (void)gpsd_switch_driver(session, (*dp)->type_name);
> -                 break;
> -             }
> +         /*
> +          * Only switch drivers, if we don't already have one with the
> +          * matching packet type.
> +          */
> +         if (first_sync ||
> +             session->packet.type != session->device_type->packet_type) {
> +             for (dp = gpsd_drivers; *dp; dp++)
> +                 if (session->packet.type == (*dp)->packet_type) {
> +                     (void)gpsd_switch_driver(session, (*dp)->type_name);
> +                     break;
> +                 }
> +         }
>           /* FALL THROUGH */
>       } else if (session->getcount++>1 && !gpsd_next_hunt_setting(session)) {
>           gpsd_run_device_hook(session->gpsdata.dev.path, "DEACTIVATE");
>