| Message ID | 8c2648ec-1379-fb2a-35d2-b3fa8fc9f063@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 <mathieu.poirier@linaro.org> > >Cc: Alex Williamson <alex.williamson@redhat.com> > >Cc: Eric Auger <eric.auger@redhat.com> > >Cc: Russell King <linux@armlinux.org.uk> > >Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > >Cc: Todd Kjos <tkjos@google.com> > >Cc: Geert Uytterhoeven <geert+renesas@glider.be> > >Cc: Thierry Reding <treding@nvidia.com> > >Cc: Robin Murphy <robin.murphy@arm.com> > >Signed-off-by: Kim Phillips <kim.phillips@arm.com> > >--- > >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 <robin.murphy@arm.com> > > 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 >
On 09/05/18 16:40, Mathieu Poirier wrote: > 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 <mathieu.poirier@linaro.org> >>> Cc: Alex Williamson <alex.williamson@redhat.com> >>> Cc: Eric Auger <eric.auger@redhat.com> >>> Cc: Russell King <linux@armlinux.org.uk> >>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >>> Cc: Todd Kjos <tkjos@google.com> >>> Cc: Geert Uytterhoeven <geert+renesas@glider.be> >>> Cc: Thierry Reding <treding@nvidia.com> >>> Cc: Robin Murphy <robin.murphy@arm.com> >>> Signed-off-by: Kim Phillips <kim.phillips@arm.com> >>> --- >>> 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 <robin.murphy@arm.com> >> >> 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. Ah, now I see that obvious thing I was indeed missing - I got mixed up and started thinking bus_add_device() only got called as part of driver probe, but of course it's actually much earlier in {platform,amba}_device_add(). That means my idea cannot in fact work at all, since both ends of any link would defer waiting for the other to probe (and thus call coresight_register()) first. Oh well, I guess poking amba_bustype really does remain the only reasonable answer. Thanks, Robin.
On Wed, 9 May 2018 17:02:34 +0100 Robin Murphy <robin.murphy@arm.com> wrote: > probe (and thus call coresight_register()) first. Oh well, I guess > poking amba_bustype really does remain the only reasonable answer. Thanks all, I've added Robin's Reviewed-by, and submitted this patch to RMK's patch tracking system, here: http://www.armlinux.org.uk/developer/patches/viewpatch.php?id=8773/1 Cheers, Kim
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); }