At Mon, 21 Jul 2003 19:19:17 -0700 (PDT), Eliot Blennerhassett wrote: > > Takashi Iwai wrote: > > Hi, > > > > so far, some pcm operator callbacks are assumed to be atomic. > > but looking at the code, this restriction seems coming only from the > > rwlock of linked streams. > > > > there are some hardwares which need (idally) the non-atomic operations > > for prepare and trigger. they usually require the ack as the command > > completion. and we implemented it in the busy loop or by ignoring the > > ack. > > Can you point me to an example...
korg1212 and vx drivers do in these ways. > I would be very glad if operators were non-atomic (I could handle .pointer being > atomic). > I have had to replace a semaphore with a spinlock around my card access code > because there are a few paths that come from atomic context. yes, this is the very reason i posted. > Maybe it is a big picture design flaw... it's rather a subtle thing in the total design, i'd like to say :) in most parts you don't need to change. > > i think the stream-link lock can be replaced with rw_semaphore, so > > that prepare and trigger callbacks can be non-atomic. the only > > critical part is, as far as i see, that snd_pcm_stop() may be called > > from interrupt handler when xrun/suspend happens. this cannot handle > > the semaphore, of course. > > > > i have still no concrete idea how to solve this... any suggestions? > > Is it possible that semaphores can be used in atomic context if down_trylock() > is used in a loop? Really what is not allowed is for process to try to sleep > when in atomic context. no, this will surely cause a deadlock. > Now I think about it it would cause a deadlock. How about have the interrupt > flag the need to stop after the competing process relinquished the semaphore? that's what i thought of, too... ciao, Takashi ------------------------------------------------------- This SF.net email is sponsored by: VM Ware With VMware you can run multiple operating systems on a single machine. WITHOUT REBOOTING! Mix Linux / Windows / Novell virtual machines at the same time. Free trial click here: http://www.vmware.com/wl/offer/345/0 _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
