On Tue, 21 Apr 2015 18:01:00 -0500 , Rob Herring <robherri...@gmail.com> wrote: > On Tue, Apr 21, 2015 at 4:09 PM, Ricardo Ribalda Delgado > <ricardo.riba...@gmail.com> wrote: > > Hello Rob > > > > On Tue, Apr 21, 2015 at 10:13 PM, Rob Herring <robherri...@gmail.com> wrote: > >> On Tue, Apr 21, 2015 at 3:25 AM, Ricardo Ribalda Delgado > >> <ricardo.riba...@gmail.com> wrote: > >>> of_platform_device_create_pdata() was using of_device_add() to create > >>> the devices, but of_platform_device_destroy was using > >>> of_platform_device_destroy(). > >>> > >>> of_device_add(), do not call insert_resource(), which initializes the > >>> parent field of the resource structure, needed by release_resource(), > >>> called by of_platform_device_destroy(). > >> > >> This is because some DTs have overlapping resources and doing this > >> would break things. If you look at the git history, this was fixed and > >> then reverted by Grant. > > > > I cannot find that commit sorry, could you give me the hash or a link > > to the mailing list? > > > > ricardo@pilix:~/linux$ git shortlog drivers/of/platform.c | grep -i Revert > > Revert "drivers: of: add initialization code for dma reserved memory" > > commit 02bbde7849e68e193cefaa1885fe0df0f03c9fcd > Author: Grant Likely <grant.lik...@secretlab.ca> > Date: Sun Feb 17 20:03:27 2013 +0000 > > Revert "of: use platform_device_add" > > This reverts commit aac73f34542bc7ae4317928d2eabfeb21d247323. That > commit causes two kinds of breakage; it breaks registration of AMBA > devices when one of the parent nodes already contains overlapping > resource regions, and it breaks calls to request_region() by device > drivers in certain conditions where there are overlapping memory > regions. Both of these problems can probably be fixed, but it is better > to back out the commit and get a proper fix designed before trying again. > > Signed-off-by: Grant Likely <grant.lik...@secretlab.ca> > > > > > > > To give a litte context to this patch, the issue started with this > > conversaion with Bjorn: > > https://lkml.org/lkml/2015/4/20/435 > > > > > > What we have today is also wrong, it leads to a null pointer deference > > (and therefore a whole crash). > > > > If we cannot use platform_device_add, then we cannot use > > platform_device_destroy :) > > > > Shall I prepare a patch replacing platform_device_destroy()? > > Perhaps we make inserting resource failure non-fatal so by default we > can have resources inserted but not break the cases Grant mentioned. > Ideally we want to not have new platforms with overlapping resources > in the DT.
I think I tried that too and then ran in to a problem where drivers will fail if a different device 'owns' the resource. For example, if device-a and device-b have overlapping regions, device-a gets registered first and claims the region. device-b tries to claim the region, fails, but is allowed to continue anyway. When driver-b tries to bind to device-b, and does a request_resource(), it will fail because device-a already owns it. I don't have a good solution for that other than to completely disable insert_resource() when using devicetree. g. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
