[Letux-kernel] LetuxOS: Kernel: m-rc 5.3-rc1 successful

H. Nikolaus Schaller hns at goldelico.com
Tue Jul 30 17:41:10 CEST 2019

Some additional thoughts:

* here is the "Issue" record: http://projects.goldelico.com/p/gta04-kernel/issues/883/

* the letux/pyra-minimal branch is without any AESS patch (on top of 5.3-rc2).
  I tried audio yesterday on the Pyra but did not get more than scratchy noise :(

* There was a really good description on omappedia but I think it has gone.

* I think the Droid 4 is omap4430 + twl6040 + telephony modem and therefore the
developers may also be interested in this.

> Am 30.07.2019 um 17:21 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> Hi,
>> Am 30.07.2019 um 16:29 schrieb N. Jackson <nljlistbox2 at gmail.com>:
>> At 10:22 +0200 on Tuesday 2019-07-23, H. Nikolaus Schaller wrote:
>>> a) the AESS patches by Peter we are carrying along did no
>>> longer compile.
>>> Reason is that some members of the dai_link struct have
>>> been replaced by pointers to other structs. The macros
>>> used to initialize them can no longer be used.
>>> Therefore I have simply disabled the offending code
>>> lines.
>>> Note: this is not yet fixed in the letux/pyra-minimal tree.
>>> Generally we need someone who looks at this code pile
>>> and brings them into a better shape. Ideally it would
>>> be made working incl. AESS firmware load and pushed
>>> upstream :)
>> What is the rationale for the AESS patches in Letux? Does Linux
>> currently have no AESS support, or do these patches modify
>> existing Linux AESS support? If the latter, are the AESS patches
>> in Letux fixing bugs or adding features?
> No, there is no AESS in kernel.org. Andrej did port an older
> version written by Peter (CC:) and I made it work (well compile)
> again on newer mainline kernels.
> What is not working is firmware loading.
> And there are bugs in the integration (API to setup DAI links etc.
> has changed).
> So we carry that code along in the hope that Peter or someone
> else finds the time to fix the issues introduced by not having
> it upstream.
>> If the former (no existing AESS support in Linux), then does the
>> hardware targeted by Letux not have audio capabilities
>> (alternative to AESS) for which there is existing support in
>> Linux?
> Yes. Of course. Think of it as a coprocessor like a GPU.
> Without AESS we can use the upstream twl6040 driver directly
> and use it as a simple sound card through aplay. This is the
> status you get if you use omap2plus_defconfig and/or build a
> kernel for Pandaboard or OMAP5EVM.
> But AESS has some nice features:
> * can run independently of OMAP5
> * allows to mix headset, modem audio, bluetooth microphone etc.
>  i.e. between all McBSP interfaces
> * audio filters
> These features make it interesting to use. But: this needs a
> binary blob (like GPU or WiFi chips), which is a no-go for FLOSS
> purists.
> BTW: the OMAP4 + twl6040 (PandaBoard) has the same AESS.
> BR,
> Nikolaus
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