Linux/AM5718: camera sensor interfacing with ti-cal driver

Simit Ghane

Intellectual 980 points

Part Number: AM5718
Other Parts Discussed in Thread: DRA72

Tool/software: Linux

Hi All,

We are working on AM5718 custom board and using linux kernel version :4.9.59.

We are interfacing camera sensor with TI-CAL driver and processing it in the application.

we wan't to know how much data can be read on single DDR clk.?

can we increase the speed by neglecting the write cycle during Read operation or neglecting the read cycle during write operation.

If there is specific document available to understand read/write cycle from sensor to the DDR RAM for each clock then please guide us it will be really helpfull.

Thanks,

Simit

over 6 years ago

0 Mohsen Khayami over 6 years ago

TI__Mastermind 22391 points

Hi Simit
The best performance would be to use the EDMA versus the CPU transfers. You can take a look at the below site it has information about what you are asking for the DDR. It does say DRA74/DRA72. The performance on the DDR is the same for the AM571x and the DRA72x.

www.ti.com/.../sprac46a.pdf

let me know if that helps.

0 Manisha Agrawal over 6 years ago

TI__Mastermind 22946 points

Hi Simit,

How much data can be read from DDR on a single clock depends upon the bus width of the interface. Are you asking for CAL interface read rate or ARM processing speed or something else?

Regards,
Manisha

0 Simit Ghane over 6 years ago in reply to Manisha Agrawal

Intellectual 980 points

Hi Manisha,

We need the Details for below operation
1) CAL interface read
2) Copy from memory to meory (memcopy)
3) Copy data from DMA to memory

Thanks,

Simit

0 Manisha Agrawal over 6 years ago in reply to Simit Ghane

TI__Mastermind 22946 points

1. 600 MBytes/sec
2. 2467 MBytes/sec
3. There is no user space DMA APIs on linux. Which DMA are you referring here.

0 Simit Ghane over 6 years ago in reply to Manisha Agrawal

Intellectual 980 points

Hi Manisha,

There is no user space DMA APIs on linux. Which DMA are you referring here.

-> We are referring dual-camera-demo which using CMEM it is working on the fundamental of DMA right?

So will you please explain how loopback.c will work is it using DMA or not?

And how it is better then mmap ?

Thanks,

Simit

0 Manisha Agrawal over 6 years ago in reply to Simit Ghane

TI__Mastermind 22946 points

Hi Simit,

In dual-camera demo, the capture driver (VIP) writes to CMEM buffer using vpdma (DMA engine inside the VIP). The CMEM buffers are cache enabled and CPU access those buffers directly to do JPEG compression on them. There is no DMA based access by CPU. Once CPU is done with the processing, it flushes the cache and release the buffer.

Regards,
Manisha

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Linux/AM5718: camera sensor interfacing with ti-cal driver