TAS2781: Mixer works with in-kernel Linux driver but not TI-supplied one

Douglas Mandell

Part Number: TAS2781

Tool/software:

Greetings,

We have a in-house-developed board that contains two TAS2781 amplifier chips, and is controlled by an attached Raspberry Pi CM4. When I use the TAS2781 driver included in the kernel source, the amixer program is able to see the controls of the amplifiers, but when I use the TI-supplied driver, which includes additional debugging capability, the amixer program finds no device controls. In both cases the PCM device shows up. I haven't gotten as far as playing any audio yet-- I wanted to figure out the control issue first.

Also, it seems that the names for the firmware files are different for the different drivers, and what's more frustrating is that these name don't seem to be documented anywhere! I have to pore over the ouput of dmesg looking for firmware file-not-found errors from the driver!

In both cases I'm using the same device tree overlay, and I'm not 100% certain that I have it right.

All help gratefully accepted. Thanks,

--Douglas Mandell

8 months ago

0 Arthur Brown 8 months ago

TI__Mastermind 20775 points

Hi Douglas

I am including our driver support team in this case, They are based in china and may have poor availability due to the Chinese new year.

I was checking some discussion I had had with him earlier and i believe the code recognized by the Linux community (tas2781-i2c.c « codecs « soc « sound - kernel/git/torvalds/linux.git - Linux kernel source tree) is more official than the code on git.ti.com

Regards,
Arthur

0 Shenghao Ding 8 months ago

TI__Genius 11640 points

Hi Guy

At least, you must push rca file into /lib/firmware for bypass playback?

If you want to have dsp inside tas2781 work, pls also generate a dsp bin file.

Guideline for driver porting: PowerPoint 演示文稿

Guideline for spk calibration: PowerPoint 演示文稿

template for rca file: jsn « regbin - tas2781-linux-drivers/tas2781-linux-driver - Unnamed repository; edit this file 'description' to name the repository.

As to spk modelling ans dsp acoustic tuning, kindly consult our hardware expert.

0 Douglas Mandell 7 months ago in reply to Shenghao Ding

Prodigy 30 points

Hi Shenhao,

Yes, when I put files into the /lib/firmware they appear to be accepted by the driver. I was trying to determine whether to use the drivers in TI's git repository or the ones included in the Linux source tree, and Arthur thinks that the ones included in Linux might be a better choice.

I think I have it figured out, but could you please confirm for the Linux-supplied driver, exactly what should the names of the firmware files be? As I understand it, there are three files, one that sets registers, one that supplies DSP, and a third one with speaker calibration information, right?

Thanks,

--Douglas Mandell

0 Douglas Mandell 7 months ago in reply to Arthur Brown

Prodigy 30 points

Hi Arthur,

Thanks for the information. I'll concentrate my work on the "official" driver in the Linux kernel tree.

--Douglas

0 Shenghao Ding 7 months ago in reply to Douglas Mandell

TI__Genius 11640 points

What kernel version do you use? And how many pieces of tas2781 are on your device?

tas2781-coef.bin is the dsp firmware and acoustic params, will be generated by PPC3, pls apply for the tool in this link PUREPATHCONSOLE Application software & framework | TI.com

%sRCA%d.bin is the regsiter setting for the tas2781, tas2781RCA2.bin is for two pieces of tas2781,

tas2781RCA1.bin is for one piece of tas2781. It is generated by regbin tool(Non_Integrated_Bin_Tool_v1.4.1 « toolset « regbin - tas2781-linux-drivers/tas2781-linux-driver - Unnamed repository; edit this file 'description' to name the repository.)
with json file(jsn « regbin - tas2781-linux-drivers/tas2781-linux-driver - Unnamed repository; edit this file 'description' to name the repository.)

The guideling for regbin tool is git.ti.com/cgit/tas2781-linux-drivers/tas2781-linux-driver/plain/regbin/toolset/Regbin Tool User Guideline.pdf

%s-%s_cal_0x%02x.bin is generated by the fct-tool, after you spk must have spk charactering and dsp fw work properly.

0 Douglas Mandell 7 months ago in reply to Shenghao Ding

Prodigy 30 points

Hi Shenhao,

Our board has two TAS2781 chips on it, and we're using Linux kernel 6.6.70.

Thanks for the information on file names for the .bin files. That tells me how I need to name the files.

I already have PPC3 and I created the tas2781RCA2.bin and tas2781_coef.bin (it seems that the driver needs an underscore '_' not a dash '-' in the filename.) The driver included in Linux accepts these files without complaint, and the device shows up in the list of both aplay and amixer.

Now that I'm back working on this board, hopefully I'll get sound out of it soon!

Thanks,

--Douglas Mandell

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TAS2781: Mixer works with in-kernel Linux driver but not TI-supplied one