From: Vinod Koul <vkoul@kernel.org>
To: Pierre-Louis Bossart <pierre-louis.bossart@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,
Bard Liao <yung-chuan.liao@linux.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: Fri, 28 Aug 2020 12:57:42 +0530 [thread overview]
Message-ID: <20200828072742.GL2639@vkoul-mobl> (raw)
In-Reply-To: <d534afc3-3c38-275e-2f62-0432ffd91a36@linux.intel.com>
On 26-08-20, 09:09, Pierre-Louis Bossart wrote:
>
>
> > > + * @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.
Okay, it would be better if we move it to intel driver, but I see it may
not be trivial, so lets go with this approach.
--
~Vinod
next prev parent reply other threads:[~2020-08-28 7:28 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
2020-08-28 7:27 ` Vinod Koul [this message]
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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