Support for Botic Linux driver

[coroner21]

I do not get this attitude... Why bother with DIY at all if it is too much effort? Just get a ready-made device running volumio like this volumio primo and be done with it.

[coroner21]

The linux kernel for Arch Linux ARM with botic patches on GitHub - coroner21/linux-am33xbot: Arch Linux ARM Kernel with botic patches was updated to version 5.3.7.

ATTENTION: Due to a major rework of the code of the machine driver (botic-card module), the driver in this repository currently only works for standard Cronus devices populated with two clocks and a GPIO switch to change frequencies. Configurations using the internal clock and accompanying it with an external clock for 44.1kHz frequencies currently do not work. Also using only one clock is currently not supported by the updated driver. If someone requires other configurations than the standard Cronus / Hermes boards let me know and I will enhance the driver again.

Please also read through the instructions on the github page regarding non-default clock frequencies. The device tree overlay needs to be edited in case frequencies other than the 49.152MHz / 45.1584MHz pair should be used.

[miero]

coroner21, thanks for maintaining this.

I suggest you to copy & update also the README file of the driver to the GIT repository:
- http://bbb.ieero.com/botic5/README-botic5

[coroner21]

Just to ensure that the debian users (with probably higher user base then Arch) also have a chance to use an updated kernel and the latest debian version: You can find a debian buster SD card (4GB) image here: Filebin

The link is valid one week. Please verify sha256sum:

6d85581559f2e95705d0057f4d6f3d86810286f22a5183d9cbf4d33cc74be928

This image was downloaded from bb.org today and includes only following modifications compared to the stock bb.org image:

• kernel upgrade was installed (including botic patches for playback)
• /boot/uEnv.txt was edited to enable the base BOTIC-00A0.dtbo overlay (i2s/dsd output, i2c control of any DAC connected to I2C bus 1 has to be done using scripts out of kernel space)

I tested sound output to a stereo DAC but nothing else. Since I do not use debian myself please check for yourself whether things are working alright.

[ppy]

Originally Posted by coroner21

If someone requires other configurations than the standard Cronus / Hermes boards let me know and I will enhance the driver again.

Will it not be difficult for you to add these changes for mute to work correctly?
GitHub - luchoh/botic-dev at mute-v48

[Abra]

Originally Posted by coroner21

Just to ensure that the debian users ... (

Thank you for the support! I will try it soon.

[coroner21]

Originally Posted by ppy

Will it not be difficult for you to add these changes for mute to work correctly?
GitHub - luchoh/botic-dev at mute-v48

For me the way this is implemented looks like it is a simple GPIO switch to control a mute signal using one of the existing AXR pins of the McASP controller. I have to admit that I do not want to tinker so much with the McASP code especially since I do not use any mute signal myself (why is it necessary, what you want to achieve with it?)...


Anyways, I see that with the most recent McASP code it seems to be easily possible to use the McASP as a GPIO controller and several optional device tree bindings for this purpose have been added. Would it be possible to simply use this existing functionality?


In general I see that mute_stream / digital_mute seems to be implemented mainly for codecs rather than cpu DAIs. Would it make sense to specify a GPIO from McASP GPIO controller and use it in the codec to set it to HIGH / LOW for mute control?

[ppy]

My DSC2 project is DSD-only DAC. No signal mute very loud clicks.
Therefore, in my mini firmware for BBB, I can only use the 4.X kernel version and this patch

[amigo1]

Originally Posted by coroner21

Just to ensure that the debian users (with probably higher user base then Arch) also have a chance to use an updated kernel and the latest debian version: You can find a debian buster SD card (4GB) image here: Filebin

The link is valid one week. Please verify sha256sum:

6d85581559f2e95705d0057f4d6f3d86810286f22a5183d9cbf4d33cc74be928

This image was downloaded from bb.org today and includes only following modifications compared to the stock bb.org image:

• kernel upgrade was installed (including botic patches for playback)
• /boot/uEnv.txt was edited to enable the base BOTIC-00A0.dtbo overlay (i2s/dsd output, i2c control of any DAC connected to I2C bus 1 has to be done using scripts out of kernel space)

I tested sound output to a stereo DAC but nothing else. Since I do not use debian myself please check for yourself whether things are working alright.

Please clarify! Have You modified img bone-debian-10.0-iot-armhf-2019-07-07-4gb.img.xz ? Index of /images/

[coroner21]

Originally Posted by ppy

My DSC2 project is DSD-only DAC. No signal mute very loud clicks.
Therefore, in my mini firmware for BBB, I can only use the 4.X kernel version and this patch

I see that you use AXR3 / GPIO3_19 as mute pin. Rather than hacking the GPIO usage into the McASP module, it would be much more easy in your case to simply setup the McASP to use two serializers only (AXR0 / AXR1 as required for two DSD channels).

My suggestion would be then to integrate the mute rather in the generic BOTIC codec as an optional GPIO that is claimed in case it is configured in the device tree as part of the codec node (e.g. mute-gpios = <&gpio3 19 0>) and implement the digital_mute function as part of the snd_soc_dai_ops for the codec. If you are willing to test this, I can quickly add the required code to the Arch Linux ARM kernel and provide instructions. Unfortunately I have no way of testing it myself since the ESS DACs seem to do just fine even without any mute being applied.

Also in your case (since you know that you want to only support DSD sample formats) it might make sense to change the botic-codec definitions so that they only include DSD. That way you would not even need the DSD switch since ALSA would already error out.