Hi Lorenzo,
On 2016-06-21 18:06, Lorenzo Pieralisi wrote:
Hi Marek,
On Tue, Jun 21, 2016 at 09:53:20AM +0200, Marek Szyprowski wrote:
Hi Robin,
On 2016-06-17 11:27, Robin Murphy wrote:
Hi Lorenzo,
I think this patch makes sense even independent of the rest of the
series, one nit inline notwithstanding.
Marek; I'm curious as to whether this could make the workaround in
722ec35f7 obsolete as well, or are all the drivers also bound
super-early in the setup you had there?
Yes, this will solve that problem too. I will also hide some possible
deferred probe issues, because the moment at which IOMMU is activated
will be postponed. The only drawback with this approach is the fact
that is drivers won't be allowed to do any dma-mapping operations on
devices, which they don't own. This should not be a big issue, but
this was the reason to setup IOMMU on device add instead of driver
bind.
While at it, please make sure that the case of failed client driver
probe will be handled properly. IOMMU might do some operations while
setting up and if the client driver fails to probe (for whatever
reason, might be a deferred probe too), those operation has to be
undone. However the current code of the driver core won't call any
notifier (like BUS_NOTIFY_UNBOUND_DRIVER or whatever else) in such
case.
Isn't Andy's commit 14b6257a5f3d enough ? Is that what you had in
mind ?
Long time ago I used BUS_NOTIFY_BIND_DRIVER based approach for my
Exynos IOMMU patches and had to extend bus core with such patch:
https://patchwork.kernel.org/patch/4678181/ to properly cleanup
after failed client driver probe and avoid leaking resources. Please
read the discussion, because some changes were requested to it.
It looks like commit 14b6257a5f3d ("device core: add
BUS_NOTIFY_DRIVER_NOT_BOUND notification") does what you
are requesting, please let me know if that's enough.
Yes, that's exactly the change I needed that time. Nice to see that it
finally landed in mainline.
I will revert the changes in 722ec35f7 and fold them in the
new version along with Robin's suggestions.
Okay.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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