From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre-Louis Bossart Subject: Re: [PATCH 2/3] ALSA: core: modify .ack callback to take arguments for updating appl ptr Date: Fri, 19 May 2017 10:01:04 -0500 Message-ID: References: <1494896518-23399-1-git-send-email-subhransu.s.prusty@intel.com> <1494896518-23399-3-git-send-email-subhransu.s.prusty@intel.com> <0be78e8b-ebc0-9f8b-5bed-df01a791f940@sakamocchi.jp> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by alsa0.perex.cz (Postfix) with ESMTP id 35E9F2667A5 for ; Fri, 19 May 2017 17:01:23 +0200 (CEST) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Takashi Iwai , Takashi Sakamoto Cc: alsa-devel@alsa-project.org, patches.audio@intel.com, lgirdwood@gmail.com, Jaikrishna Nemallapudi , broonie@kernel.org, "Subhransu S. Prusty" List-Id: alsa-devel@alsa-project.org 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 >>> >>> 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 >>> Signed-off-by: Jaikrishna Nemallapudi >>> Signed-off-by: Subhransu S. Prusty >>> --- >>> 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. > > > Takashi > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@alsa-project.org > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel >