TCI6638K2K: mutal exclusion between DSP and ARM

Vesa Peltonen

Hi all,

What is the easiest, but a fast way to protect a shared resource (a memory structure) that is used both in DSP corepacs and ARM?

Can I use the hardware semaphore from the ARM side? I.e. can I access this functionality somehow on the ARM running Linux:

- CSL_semAcquireDirect()

- CSL_semReleaseSemaphore().

thanks,vesa

(Running the latest MCSDK on the keystone 2 device, Linux on ARM and BIOS on the DSPs)

over 11 years ago

0 Vesa Peltonen over 11 years ago

Intellectual 525 points

I came accross hwspinlock. It seems that it is implemented only for OMAP, and not for keystone II platform.

Is that correct?

0 Chad Courtney over 11 years ago in reply to Vesa Peltonen

TI__Mastermind 30825 points

Vesa,

The HW Semaphore should be accessible via the ARM side, I'll ping someone from the ARM SW side to comment on what code source we have available for this.

Keystone devices do not provide a HW Spinlock as used on OMAP.

Best Regards,

Chad

0 Vesa Peltonen over 11 years ago in reply to Chad Courtney

Intellectual 525 points

Happy New year to all!
Any news on this ARM/DSP semaphore thing?

0 Chad Courtney over 11 years ago in reply to Vesa Peltonen

TI__Mastermind 30825 points

Vesa,

I apologize for not getting back to you earlier on this, but yes, I confirmed that the HW Semaphore is accessible by the ARM too.

For DSP cores it 0 to 7 and for the A15 ARM cores it's 8 to 11.

Best Regards,

Chad

0 Vesa Peltonen over 11 years ago in reply to Chad Courtney

Intellectual 525 points

Thanks Chad for the confirmation.

Do you know where I can find an example/a documentation how to access the HW semaphore in Linux(user space)? Is there some device driver which enables this access?

thanks, Vesa

0 Chad Courtney over 11 years ago in reply to Vesa Peltonen

TI__Mastermind 30825 points

Let me ping someone from the Linux SW side to address that.

Best Regards,

Chad

0 Joey Landmark over 11 years ago in reply to Chad Courtney

Prodigy 110 points

Any update on this? I too am looking at a way to protect a shared resource across DSPs and ARM using the same HW semaphore.

How is this done from Linux user space?

Thanks

0 Vesa Peltonen over 11 years ago in reply to Joey Landmark

Intellectual 525 points

Hello,

still waiting as well for input on this topic.

Cheers,

Vesa

0 Chad Courtney over 11 years ago in reply to Vesa Peltonen

TI__Mastermind 30825 points

Vesa,

Sorry, that portion was re-assigned, but it looks like there was no follow up. I've re-pinged the person it was re-assigned to.

Best Regards,

Chad

0 Rex Chang over 11 years ago in reply to Chad Courtney

TI__Guru 50170 points

Hi, Vesa,

The CSL semaphore functions are not exposed to user's space. I am not sure what the application is, but for ARM and DSP accessing the share memory, there is an IPC example in MCSDK release where data are transferred between ARM and DSP. An message is sent to notify that the shared memory is free for the other party to use.

Rex

Processors

Processors forum

TCI6638K2K: mutal exclusion between DSP and ARM