Am 22.07.2014 06:05, schrieb Dave Airlie:
On 9 July 2014 22:29, Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxx> wrote:
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxx>
---
drivers/gpu/drm/radeon/radeon.h | 15 +-
drivers/gpu/drm/radeon/radeon_device.c | 60 ++++++++-
drivers/gpu/drm/radeon/radeon_fence.c | 223 ++++++++++++++++++++++++++------
3 files changed, 248 insertions(+), 50 deletions(-)
From what I can see this is still suffering from the problem that we
need to find a proper solution to,
My summary of the issues after talking to Jerome and Ben and
re-reading things is:
We really need to work out a better interface into the drivers to be
able to avoid random atomic entrypoints,
Which is exactly what I criticized from the very first beginning. Good
to know that I'm not the only one thinking that this isn't such a good idea.
I'm sure you have some ideas and I think you really need to
investigate them to move this thing forward,
even it if means some issues with android sync pts.
Actually I think that TTMs fence interface already gave quite a good
hint how it might look like. I can only guess that this won't fit with
the Android stuff, otherwise I can't see a good reason why we didn't
stick with that.
but none of the two major drivers seem to want the interface as-is so
something needs to give
My major question is why we need an atomic callback here at all, what
scenario does it cover?
Agree totally. As far as I can see all current uses of the interface are
of the kind of waiting for a fence to signal.
No need for any callback from one driver into another, especially not in
atomic context. If a driver needs such a functionality it should just
start up a kernel thread and do it's waiting there.
This obviously shouldn't be an obstacle for pure hardware
implementations where one driver signals a semaphore another driver is
waiting for, or a high signal on an interrupt line directly wired
between two chips. And I think this is a completely different topic and
not necessarily part of the common fence interface we should currently
focus on.
Christian.
Surely we can use a workqueue based callback to ask a driver to check
its signalling, is it really
that urgent?
Dave.
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