On 16.11.2011 01:24, Jerome Glisse wrote: > Well as we don't specify on which value semaphore should wait on, i am > prety sure the first ring to increment the semaphore will unblock all > waiter. So if you have ring1 that want to wait on ring2 and ring3 as > soon as ring2 or ring3 is done ring1 will go one while either ring2 or > ring3 might not be done. I will test that tomorrow but from doc i have > it seems so. Thus it will be broken with more than one ring, that > would mean you have to allocate one semaphore for each ring couple you > want to synchronize. Note that the usual case will likely be sync btw > 2 ring.
Good point, but I played with it a bit more today and it is just behaving as I thought it would be. A single signal command will just unblock a single waiter, even if there are multiple waiters currently for this semaphore, the only thing you can't tell is which waiter will come first. I should also note that the current algorithm will just emit multiple wait operations to a single ring, and spread the signal operations to all other rings we are interested in. That isn't very efficient, but should indeed work quite fine. > After retesting the first patch drm/radeon: fix debugfs handling is NAK > a complete no go. > > Issue is that radeon_debugfs_cleanup is call after rdev is free. This > is why i used a static array. I forgot about that, i should have put a > comment. I guess you built your kernel without debugfs or that you > didn't tested to reload the module. Mhm, I have tested it, seen the crash, and didn't thought that this is a problem. Don't ask me why I can't understand it myself right now. Anyway, I moved the unregistering of the files into a separate function, which is now called from radeon_device_fini instead of radeon_debugfs_cleanup. That seems to work fine, at least if I haven't missed something else. I also merged your indention fixes and the fix for the never allocated semaphores and pushed the result into my public repository (http://cgit.freedesktop.org/~deathsimple/linux), so please take another look at it. Thanks, Christian.