Linux/TDA2PXEVM: How to access IPU memory from Linux userspace

HJ Kim

Part Number: TDA2PXEVM

Tool/software: Linux

Hi,

I'd like to access IPU memory from Linux userspace.
The receiving of the pointer of IPU memory was ok by control link from IPU to CA15.
The OSA_memPhys2Virt() was used to convert to virt address of Linux, But the converted address was 0, The result was all the same at changing mem type 0(OSA_MEM_REGION_TYPE_SR0) ~ 5(OSA_MEM_REGION_TYPE_AUTO).

Are there any APIs in visionsdk or Linux device driver is necessary for it?

Thanks

over 6 years ago

0 Brijesh Jadav over 6 years ago

TI__Guru**** 438045 points

Hi Kim,

SR regions are already mapped in the Linux, so when you call phystovirt or vice versa api, it would take care of converting it correctly. But this will be done only if the memory is allocated from the SR region. Can you please if it is allocated from SR region?

Rgds,
Brijesh

0 HJ Kim over 6 years ago in reply to Brijesh Jadav

Expert 1460 points

Hi Brijesh,

I don't understand the meaning of SR.
The memory was allocated by IPU, and Linux user space in CA15 tries to access it.

I assume that OSA_memPhys2Virt() is only available if its memory is allocated by Linux. Is it right?

Thanks.

0 Brijesh Jadav over 6 years ago in reply to HJ Kim

TI__Guru**** 438045 points

Hi Kim,

I see in the function, OSA_memInit, both OSA_MEM_REGION_TYPE_SR0 and OSA_MEM_REGION_TYPE_SR1 are already mapped in Linux userspace.
So if you have physical address allocated from SR0 or SR1 region on IPU, you could just call OSA_memPhys2Virt API to get virtual address..

Rgds,
Brijesh

0 HJ Kim over 6 years ago in reply to Brijesh Jadav

Expert 1460 points

Hi Brijesh,

Then how about for the stack memory in IPU?
Can it also be transferred to virt memory in Linux?

Could you explain how to alloc SR0 and SR1 in IPU not in kernel?

Thanks.

0 Brijesh Jadav over 6 years ago in reply to HJ Kim

TI__Guru**** 438045 points

Hi Kim,

Stack memory is local to that core, it is not mapped, so not accessible.
SR regions are shared regions, accessible on all cores. If you want to share the memory, you should allocate memory from this region.

Rgds,
Brijesh

0 HJ Kim over 6 years ago in reply to Brijesh Jadav

Expert 1460 points

Hi Brijesh,

It worked when Utils_memAlloc() was used in IPU.

I'd like to use SR regions for i2c initial data (const array) in IPU.
Should I use 2 steps of memAlloc() and copy i2c data to SR? Is the 1 step (i2c data directly to SR) is unavailable?

Thanks.

0 Brijesh Jadav over 6 years ago in reply to HJ Kim

TI__Guru**** 438045 points

Hi Kim,

Is it just one time configuration? If it is, why don't you move this configuration to A15?
Later on, for exposure control, you could create a structure with the i2c address and data and send it using link control command ??

Regards,
Brijesh

0 HJ Kim over 6 years ago in reply to Brijesh Jadav

Expert 1460 points

Hi Brijesh,

I don't want to use CA15 for one time configuration because for all the sensors to use same sequence.

Should I use Utils_memAlloc() in advance in IPU to use SR? or other ways?

Thanks.

0 Brijesh Jadav over 6 years ago in reply to HJ Kim

TI__Guru**** 438045 points

Yes, you could use Utils_memAlloc.
But somehow, you will require to inform A15 driver about the format of the I2C data, size of the I2C address, data etc..
May be you could embed this information as header in the shared memory itself.

Rgds,
Brijesh

0 HJ Kim over 6 years ago in reply to Brijesh Jadav

Expert 1460 points

Hi Brijesh,

Yes, right. i2c ch, addr and number of data are sent via shared memory itself. but the size of data are large and not fixed, so it should be sent via alloced mem.

Thank you for all your support.

HJ Kim

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Linux/TDA2PXEVM: How to access IPU memory from Linux userspace