From: Vinod Koul <vkoul@kernel.org>
To: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
tiwai@suse.de, broonie@kernel.org, gregkh@linuxfoundation.org,
jank@cadence.com, srinivas.kandagatla@linaro.org,
slawomir.blauciak@intel.com,
Bard liao <yung-chuan.liao@linux.intel.com>,
Rander Wang <rander.wang@linux.intel.com>,
Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Subject: Re: [PATCH 0/3] soundwire: use UniqueID only when relevant
Date: Sat, 9 Nov 2019 16:48:23 +0530 [thread overview]
Message-ID: <20191109111823.GD952516@vkoul-mobl> (raw)
In-Reply-To: <20191022234808.17432-1-pierre-louis.bossart@linux.intel.com>
On 22-10-19, 18:48, Pierre-Louis Bossart wrote:
> The hardware UniqueID, typically enabled with pin-strapping, is
> required during enumeration to avoid conflicts between devices of the
> same type.
>
> When there are no devices of the same type, using the UniqueID is
> overkill and results in a lot of probe errors due to mismatches
> between ACPI tables and hardware capabilities. For example it's not
> uncommon for BIOS vendors to copy/paste the same settings between
> platforms but the hardware pin-strapping is different. This is
> perfectly legit and permitted by MIPI specs.
>
> With this patchset, the UniqueID is only used when multiple devices of
> the same type are detected. The loop to detect multiple identical
> devices is not super efficient but with typically fewer than 4 devices
> per link there's no real incentive to be smarter.
>
> This change is only implemented for ACPI platforms, for DeviceTree
> there is no change.
I do not fully agree with the approach here but I do understand why this
was done and do not have a better alternative, so applied now
--
~Vinod
prev parent reply other threads:[~2019-11-09 11:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-22 23:48 [PATCH 0/3] soundwire: use UniqueID only when relevant Pierre-Louis Bossart
2019-10-22 23:48 ` [PATCH 1/3] soundwire: remove bitfield for unique_id, use u8 Pierre-Louis Bossart
2019-10-24 11:29 ` Vinod Koul
2019-10-24 12:42 ` [alsa-devel] " Pierre-Louis Bossart
2019-10-22 23:48 ` [PATCH 2/3] soundwire: slave: add helper to extract slave ID Pierre-Louis Bossart
2019-10-22 23:48 ` [PATCH 3/3] soundwire: ignore uniqueID when irrelevant Pierre-Louis Bossart
2019-10-24 11:39 ` Vinod Koul
2019-10-24 12:59 ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:30 ` [alsa-devel] [PATCH 0/3] soundwire: use UniqueID only when relevant Pierre-Louis Bossart
2019-11-09 11:18 ` Vinod Koul [this message]
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