On 10/2/18 12:57 AM, Jenny TC wrote:
Some DMICs need clock to be running for a specified duration as per the
DMIC spec to complete the mode transition like sleep to mormal, off to normal
etc.
Jenny TC (2):
ASoC: dmic: Enable ACPI device entry
ASoC: dmic: Introduce mode switch delay
sound/soc/codecs/dmic.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
Sorry for the late feedback.
Allowing some timing adjustments for the clock transitions is a good
thing. The way it's done is questionable and raises a number of concerns.
First, there was an Intel internal discussion before my extended break
on why this 'dmic-codec' is needed on Intel platforms. To the best of my
knowledge we don't control the mics with GPIOs, which was the initial
purpose of this driver. We have experimental evidence on ApolloLake and
GeminiLake that using the soc-dummy/soc-dummy-dai definitions are
enough, and it may be a good thing to agree on the direction here. If
you want a parameter, you can still use a machine driver DMI-based
kernel quirk and/or pass a kernel parameter, the need to extend this
dmic-codec is far from obvious to me.
Assuming you still want to use this codec, then there are still major
concerns about the ACPI directions. As Mark noted it, "DMIC" does not
follow any of the guidelines or accepted definitions with an unambiguous
vendor and part ID. We know we already have conflicts between
Intel-defined ACPI IDs, e.g. for RT298 on multiple platforms, let's be
careful here, shall we?
And I am coming to my last point. The Skylake driver already contains
code to create the dmic devices by hand (see below the git grep
results). So I wonder what happens if you use both ACPI-based
enumeration AND manually create the dmic device - I view these solutions
as mutually incompatible. Either you have not tested against the
upstream code or something is missing from your patchset. What am I missing?
-Pierre
skl.c:static int skl_dmic_device_register(struct skl *skl)
skl.c: /* SKL has one dmic port, so allocate dmic device for this */
skl.c: pdev = platform_device_alloc("dmic-codec", -1);
skl.c: dev_err(bus->dev, "failed to allocate dmic device\n");
skl.c: dev_err(bus->dev, "failed to add dmic device: %d\n", ret);
skl.c: skl->dmic_dev = pdev;
skl.c:static void skl_dmic_device_unregister(struct skl *skl)
skl.c: if (skl->dmic_dev)
skl.c: platform_device_unregister(skl->dmic_dev);
skl.c: /* create device for soc dmic */
skl.c: err = skl_dmic_device_register(skl);
skl.c: skl_dmic_device_unregister(skl);
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