From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
To: Vinod Koul <vkoul@kernel.org>,
Bard Liao <yung-chuan.liao@linux.intel.com>
Cc: alsa-devel@alsa-project.org, tiwai@suse.de,
gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
ranjani.sridharan@linux.intel.com, hui.wang@canonical.com,
broonie@kernel.org, srinivas.kandagatla@linaro.org,
jank@cadence.com, mengdong.lin@intel.com,
sanyog.r.kale@intel.com, rander.wang@linux.intel.com,
bard.liao@intel.com
Subject: Re: [PATCH 05/11] soundwire: bus: update multi-link definition with hw sync details
Date: Wed, 26 Aug 2020 09:09:14 -0500 [thread overview]
Message-ID: <d534afc3-3c38-275e-2f62-0432ffd91a36@linux.intel.com> (raw)
In-Reply-To: <20200826094420.GA2639@vkoul-mobl>
>> + * @hw_sync_min_links: Number of links used by a stream above which
>> + * hardware-based synchronization is required. This value is only
>> + * meaningful if multi_link is set. If set to 1, hardware-based
>> + * synchronization will be used even if a stream only uses a single
>> + * SoundWire segment.
>
> Soundwire spec does not say anything about multi-link so this is left to
> implementer. Assuming that value of 1 would mean hw based sync will
> be used even for single stream does not make sense in generic terms.
> Maybe yes for Intel but may not be true for everyone?
hw-based sync is required for Intel even for single stream. It's been
part of the recommended programming flows since the beginning but
ignored so far.
That said, this value is set by each master implementation, no one
forces non-Intel users to implement an Intel-specific requirement.
> We already use m_rt_count in code for this, so the question is why is
> that not sufficient?
Because as you rightly said above, Intel requires the hw_sync to be used
even for single stream, but we didn't want others to be forced to use
the hw-sync for single stream. the m_rt_count is not sufficient for Intel.
I think we are in agreement on not forcing everyone to follow what is
required by Intel, and that's precisely why we added this setting. If
you set it to two you would only use hw_sync when two masters are used.
next prev parent reply other threads:[~2020-08-26 14:41 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-18 2:41 [PATCH 00/11] soundwire: intel: add multi-link support Bard Liao
2020-08-18 2:41 ` [PATCH 01/11] soundwire: intel: disable shim wake on suspend Bard Liao
2020-08-18 2:41 ` [PATCH 02/11] soundwire: intel: ignore software command retries Bard Liao
2020-08-18 2:41 ` [PATCH 03/11] soundwire: intel: add multi-link support Bard Liao
2020-08-18 2:41 ` [PATCH 04/11] soundwire: intel: add missing support for all clock stop modes Bard Liao
2020-08-18 2:41 ` [PATCH 05/11] soundwire: bus: update multi-link definition with hw sync details Bard Liao
2020-08-26 9:44 ` Vinod Koul
2020-08-26 14:09 ` Pierre-Louis Bossart [this message]
2020-08-28 7:27 ` Vinod Koul
2020-08-18 2:41 ` [PATCH 06/11] soundwire: intel: add multi-link hw_synchronization information Bard Liao
2020-08-18 2:41 ` [PATCH 07/11] soundwire: intel: Only call sdw stream APIs for the first cpu_dai Bard Liao
2020-08-26 9:46 ` Vinod Koul
2020-08-26 14:35 ` Pierre-Louis Bossart
2020-08-28 7:49 ` Vinod Koul
2020-08-28 1:47 ` Liao, Bard
2020-08-28 7:45 ` Vinod Koul
2020-08-28 15:07 ` Pierre-Louis Bossart
2020-08-18 2:41 ` [PATCH 08/11] soundwire: stream: enable hw_sync as needed by hardware Bard Liao
2020-08-18 2:41 ` [PATCH 09/11] soundwire: intel: add dynamic debug trace for clock-stop invalid configs Bard Liao
2020-08-26 9:48 ` Vinod Koul
2020-08-26 14:38 ` Pierre-Louis Bossart
2020-08-28 7:49 ` Vinod Koul
2020-08-28 14:54 ` Pierre-Louis Bossart
2020-08-29 11:00 ` Vinod Koul
2020-08-31 15:15 ` Pierre-Louis Bossart
2020-09-01 11:07 ` Vinod Koul
2020-09-01 13:31 ` Pierre-Louis Bossart
2020-08-18 2:41 ` [PATCH 10/11] soundwire: intel: pass link_mask information to each master Bard Liao
2020-08-18 2:41 ` [PATCH 11/11] soundwire: intel: don't manage link power individually Bard Liao
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