Hi David,

Am 01.08.2020 um 12:51 schrieb David Shah <dave@ds0.me>:

Hi Nikolaus,

One last PCB question. Is R2102 populated on production boards, if so,

yes, it is. To (optionally) provide a SYSCLK to the main board. I think it
is remaining when we tried to have the audio DAC of the Pandora on the Mainboard.

how long is the trace from R2102 to the connector? If it is non-trivial 
then removing R2102 could reduce the noise picked up by the clock.

Indeed. It is at least worth trying.

Here are some pictures.

This shows ABE-CLKS going from the omap5 to the twl6040 and then to R2102. This is ca. 50mm + 15mm




Here is the FREF-CLK1 ca. 50mm to R2101 and ca. 45mm to P2101


And finally FREF-ABE-CLK R2101/02 to P2102:


This is unconnected on the Mainboard.

So removing R2102 may remove ca. 5mm which isn't much.

Best regards,
Nikolaus



Best

David

On Fri, 2020-07-31 at 21:12 +0100, David Shah wrote:
On Fri, 2020-07-31 at 20:05 +0200, Michael Mrozek wrote:
Am Freitag, den 31.07.2020, 19:48 +0200 schrieb H. Nikolaus
Schaller:

Just FYI:
As daveshah can now reproduce the issue on the uEVM, we're trying
the original
SDDK from TI. With old kernel, fully working AESS, etc.

Tested this now and it still glitches when I glitch the clock. Of
course, this
doesn't necessarily replicate whatever is going on in the Pyra. And
the glitching
is slightly different, same volume but slightly more "white" and with
slightly
more of the original of the original stream still coming through - so
I guess
either the old config or the AESS does change something.

If we can glitch it there as well, then we could still try to add
the inverter -
but adding the inverter to the 500 produced CPU boards would't be
possible, I
guess.


No, not if you want to retain your sanity :)
But easy enough for me to buy an inverter and solder it to the uEVM
just for
closure on the issue if nothing else.

If it's not possible to glitch it with TIs older OS, it's likely we
can somehow
fix it.

What could be interesting is to compare the sound/soc/ti/omap-
mcpdm.c driver
as well as omap-abe-twl6040.c between v4.7 and v5.x. It is not
even necessary
to compare the letux versions since the old kernel does not have
any private
patches and we tested the newer one without letux (aess) patches.

It is a little more tricky to do that diff because the files have
been
moved to new locations.

Am 31.07.2020 um 19:29 schrieb H. Nikolaus Schaller <
hns@goldelico.com>:

The kernel tree is here:

https://git.goldelico.com/?p=letux-kernel.git;a=shortlog;h=refs/heads/letux-4.7

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