From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
To: Takashi Iwai <tiwai@suse.de>,
"Subhransu S. Prusty" <subhransu.s.prusty@intel.com>
Cc: patches.audio@intel.com, alsa-devel@alsa-project.org,
broonie@kernel.org, lgirdwood@gmail.com
Subject: Re: [PATCH 7/7] ALSA: usb: take startup delay into account
Date: Mon, 3 Oct 2016 10:04:23 -0500 [thread overview]
Message-ID: <efce9dd9-b3f3-b7cf-86df-c6be4e0014cd@linux.intel.com> (raw)
In-Reply-To: <s5h4m4x33jo.wl-tiwai@suse.de>
>> For playback usages, the endpoints are started before the prepare
>> step, and valid audio data will be rendered with a delay that
>> cannot be recovered.
>> Worst-case the initial delay due to buffering of empty URBS can
>> be up to 12ms
> This is really a fix unlike other patches in the series.
> Please split it from others, so that we can apply it easily.
There was also additional discussions on this topic since I put this
together, not sure it makes sense to merge this patch at the moment.
In the Windows driver, the URBs can be submitted at a specific time,
which allows for synchronous starts of all endpoints (limited to the 1ms
frame resolution). In Linux we can't since the start time is owned by
the xhci driver and can't be modified by the class driver. I talked with
Mathias Nyman and Baolu Lu on this before the summer and of course I
became busy with other things. The short story is that there is a wider
problem with USB start and linking endpoints that should be addressed as
a single step. Maybe something to talk about at the miniconference?
next prev parent reply other threads:[~2016-10-03 15:04 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-30 12:43 [PATCH 0/7] ALSA: Add rewinds disabled, delays, max_inflight_bytes Subhransu S. Prusty
2016-09-30 12:43 ` [PATCH 1/7] ALSA: core: let low-level driver or userspace disable rewinds Subhransu S. Prusty
2016-09-30 13:22 ` Takashi Iwai
2016-10-03 4:40 ` Subhransu S. Prusty
2016-10-03 14:39 ` Pierre-Louis Bossart
2016-10-21 15:57 ` Takashi Iwai
2016-09-30 12:43 ` [PATCH 2/7] ALSA: core: add .update_appl_ptr callback for pcm ops Subhransu S. Prusty
2016-09-30 13:24 ` Takashi Iwai
2016-09-30 17:20 ` Vinod Koul
2016-09-30 18:38 ` Takashi Iwai
2016-10-03 4:36 ` Vinod Koul
2016-10-03 14:49 ` Pierre-Louis Bossart
2016-09-30 12:43 ` [PATCH 3/7] ALSA: pcm: avoid mmap of control data if .update_appl_ptr is implemented Subhransu S. Prusty
2016-09-30 13:40 ` Takashi Iwai
2016-10-03 4:43 ` Subhransu S. Prusty
2016-09-30 12:43 ` [PATCH 4/7] ALSA: core: add report of max inflight bytes Subhransu S. Prusty
2016-09-30 13:44 ` Takashi Iwai
2016-09-30 12:43 ` [PATCH 5/7] ALSA: hda: add default value for max_inflight_bytes Subhransu S. Prusty
2016-10-03 8:48 ` Hardik Shah
2016-10-03 14:44 ` Pierre-Louis Bossart
2016-09-30 12:43 ` [PATCH 6/7] ALSA: usb: no_period_wake and max_inflight_bytes report Subhransu S. Prusty
2016-09-30 12:43 ` [PATCH 7/7] ALSA: usb: take startup delay into account Subhransu S. Prusty
2016-09-30 13:44 ` Takashi Iwai
2016-10-03 15:04 ` Pierre-Louis Bossart [this message]
2016-10-21 16:00 ` Takashi Iwai
2016-10-03 6:46 ` Takashi Sakamoto
2016-10-03 15:08 ` Pierre-Louis Bossart
2016-10-03 17:31 ` Takashi Sakamoto
2016-09-30 13:13 ` [PATCH 0/7] ALSA: Add rewinds disabled, delays, max_inflight_bytes Takashi Iwai
2016-10-03 4:28 ` Subhransu S. Prusty
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