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

[Michael Mrozek]

Am Dienstag, den 30.07.2019, 17:45 +0200 schrieb H. Nikolaus Schaller:

I think the AESS is the hardware codec part of ABE, that's why it needs
the firmware running.

could be wrong though.

> > Am 30.07.2019 um 17:41 schrieb H. Nikolaus Schaller <
> > hns at goldelico.com>:
> > 
> > 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 I have found it: 
> http://omappedia.org/wiki/Audio_Drive_Arch#Audio_Back_End_.28ABE.29
> 
> "AESS" is also called "ABE" in other contexts. Somehow confusing.
> 
> ABE = Audio Back End (= inside OMAP4/5) - Audio Front End = twl6040 +
> speakers or other sound sources
> AESS = Audio Engine Sub-system (is part of ABE).
> 
> > * 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 been replaced by pointers to other structs.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
> > > 
> > > _______________________________________________
> > > http://projects.goldelico.com/p/gta04-kernel/
> > > Letux-kernel mailing list
> > > Letux-kernel at openphoenux.org
> > > http://lists.goldelico.com/mailman/listinfo.cgi/letux-kernel
> > 
> > _______________________________________________
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> > Kernel at pyra-handheld.com
> > http://pyra-handheld.com/cgi-bin/mailman/listinfo/kernel
> 
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Mit freundlichen Grüßen,

Michael Mrozek

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