On Fri, May 26, 2017 at 09:47:32AM +0200, Takashi Iwai wrote: > On Fri, 26 May 2017 09:42:43 +0200, > Vinod Koul wrote: > > > > On Mon, May 22, 2017 at 09:16:34AM +0200, Takashi Iwai wrote: > > > On Mon, 22 May 2017 07:22:19 +0200, > > > Vinod Koul wrote: > > > > > > > > On Fri, May 19, 2017 at 10:01:04AM -0500, Pierre-Louis Bossart wrote: > > > > > On 5/19/17 1:27 AM, Takashi Iwai wrote: > > > > > >On Fri, 19 May 2017 05:57:05 +0200, > > > > > >Takashi Sakamoto wrote: > > > > > >> > > > > > >>Hi, > > > > > >> > > > > > >>On May 16 2017 10:01, Subhransu S. Prusty wrote: > > > > > >>>From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx> > > > > > >>> > > > > > >>>When appl_ptr is updated let low-level driver know, e.g. to let the > > > > > >>>low-level driver/hardware pre-fetch data opportunistically. > > > > > >>> > > > > > >>>The existing .ack callback is extended with new attribute argument, to > > > > > >>>support this capability. Legacy driver subscribe to SND_PCM_ACK_LEGACY and > > > > > >>>doesn't process ack if it is not set. SND_PCM_ACK_APP_PTR can be used to > > > > > >>>process the application ptr update in the driver like in the skylake > > > > > >>>driver which can use this to inform position of appl pointer to host DMA > > > > > >>>controller. The skylake driver to process the SND_PCM_ACK_APP_PTR will be > > > > > >>>submitted with a separate patch set. > > > > > >>> > > > > > >>>In the ALSA core, this capability is independent from the NO_REWIND > > > > > >>>hardware flag. The low-level driver may however tie both options and only > > > > > >>>use the updated appl_ptr when rewinds are disabled due to hardware > > > > > >>>limitations. > > > > > >>> > > > > > >>>Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx> > > > > > >>>Signed-off-by: Jaikrishna Nemallapudi <jaikrishnax.nemallapudi@xxxxxxxxx> > > > > > >>>Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@xxxxxxxxx> > > > > > >>>--- > > > > > >>> include/sound/pcm-indirect.h | 4 ++-- > > > > > >>> include/sound/pcm.h | 8 +++++++- > > > > > >>> sound/core/pcm_lib.c | 6 ++++-- > > > > > >>> sound/core/pcm_native.c | 24 +++++++++++++++++++++++- > > > > > >>> sound/mips/hal2.c | 14 +++++++++++--- > > > > > >>> sound/pci/cs46xx/cs46xx_lib.c | 18 ++++++++++++++---- > > > > > >>> sound/pci/emu10k1/emupcm.c | 8 ++++++-- > > > > > >>> sound/pci/rme32.c | 15 ++++++++++++--- > > > > > >>> 8 files changed, 79 insertions(+), 18 deletions(-) > > > > > >> > > > > > >>I think it better to take care of > > > > > >>'drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c' as > > > > > >>well. This is a driver for sound functionality of Raspberry PI 1/zero > > > > > >>and some people may still get influences from this work. > > > > > >> > > > > > >>$ git grep -A20 'struct snd_pcm_ops' v4.12-rc1 | grep \\.ack > > > > > >>v4.12-rc1:drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c-... > > > > > >>... > > > > > > > > > > > >Yep, we need to cover all codes if we really change the PCM ops. > > > > > > > > > > The reason precisely why I preferred to avoid mucking with the > > > > > existing .ack(). we have a risk of introducing problems for legacy > > > > > and staging, not to mention out-of-tree. > > > > > > > > Patching them should be fine, and I wont mind breaking out-of tree ones, > > > > isn't that a good thing :) > > > > > > Heh, that's a fun as always :) > > > > > > Actually it's a difficult judgment when to change the API and when > > > not. This case is also in the gray zone. > > > > > > If it were only additions of some new features, I'd think of avoiding > > > to change the existing API. But, when it eventually fixes the bugs in > > > the existing drivers, we should not be too afraid of changing it. > > > > Then this case falls in the case where we are not changing API, right. If > > you agree we can post the other approach. > > Actually the changes for ack have been merged yesterday; the ack gets > called whenever appl_ptr changes. This *is* the right behavior, after > all. Thats right, so we don't need additonal arg anymore, thanks for pointing out. I had missed the patches. Will respin this on top of those changes -- ~Vinod _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
