On Wed, May 09, 2018 at 02:38:32PM +0100, Robin Murphy wrote: > Hi Kim, > > On 08/05/18 20:06, Kim Phillips wrote: > >This patch is provided in the context of allowing the Coresight driver > >subsystem to be loaded as modules. Coresight uses amba_bus in its call > >to bus_find_device() in of_coresight_get_endpoint_device() when > >searching for a configurable endpoint device. This patch allows > >Coresight to reference amba_bustype when built as a module. > > > >Cc: Mathieu Poirier <[email protected]> > >Cc: Alex Williamson <[email protected]> > >Cc: Eric Auger <[email protected]> > >Cc: Russell King <[email protected]> > >Cc: Greg Kroah-Hartman <[email protected]> > >Cc: Todd Kjos <[email protected]> > >Cc: Geert Uytterhoeven <[email protected]> > >Cc: Thierry Reding <[email protected]> > >Cc: Robin Murphy <[email protected]> > >Signed-off-by: Kim Phillips <[email protected]> > >--- > >There was a prior patch submitted by Alex W. here: > > > >https://lkml.org/lkml/2017/6/19/811 > > > >But I can't tell its fate - presume simply delayed? > > > >Coresight uses amba_bus in its call to bus_find_device() here: > > > >https://lxr.missinglinkelectronics.com/linux/drivers/hwtracing/coresight/of_coresight.c#L51 > > > >Grepping for bus_type and EXPORT shows other busses exporting their > >type, so I don't think this is the wrong approach. If, OTOH, Coresight > >needs to do something differently, please comment. > > Exposing raw bus_types is pretty ugly, but it is indeed the status quo, so > this probably is the reasonable thing to do. I suppose an amba_bus > equivalent of of_find_device_by_node() could be implemented, but for only a > single potential user that doesn't seem particularly worthwhile, since > unless some massive shake-up of how buses work comes along the bus_type will > inevitably end up being exported for other reasons anyway. So, in the > context of this series; > > Reviewed-by: Robin Murphy <[email protected]> > > However, as a wild idea for sidestepping the issue completely (or at least > keeping it within the CoreSight framework), at first glance it appears > something like the below might be feasible, although I may well be missing > some obvious reason why not. > > Thanks, > Robin. > > ----->8----- > diff --git a/drivers/hwtracing/coresight/of_coresight.c > b/drivers/hwtracing/coresight/of_coresight.c > index 7c375443ede6..2c3fdc9b63e6 100644 > --- a/drivers/hwtracing/coresight/of_coresight.c > +++ b/drivers/hwtracing/coresight/of_coresight.c > @@ -27,28 +27,13 @@ > > static int of_dev_node_match(struct device *dev, void *data) > { > - return dev->of_node == data; > + return dev->parent->of_node == data; > } > > static struct device * > of_coresight_get_endpoint_device(struct device_node *endpoint) > { > - struct device *dev = NULL; > - > - /* > - * If we have a non-configurable replicator, it will be found on the > - * platform bus. > - */ > - dev = bus_find_device(&platform_bus_type, NULL, > - endpoint, of_dev_node_match); > - if (dev) > - return dev; > - > - /* > - * We have a configurable component - circle through the AMBA bus > - * looking for the device that matches the endpoint node. > - */ > - return bus_find_device(&amba_bustype, NULL, > + return bus_find_device(&coresight_bustype, NULL, > endpoint, of_dev_node_match); > }
Hi Robin and thanks for the input. Your approach would work if all CS devices would be on the CS bus, which is not the case at discovery time when of_coresight_get_endpoint_device() is called. Mathieu >
