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 :) -- ~Vinod _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
