USB DMA DM37x

Esaias Pech

Other Parts Discussed in Thread: AM3517

Hello,

I am adding DMA functionality to a driver I wrote (driver is able to send/receive via Bulk transfers but not at the speed I need)

I have a couple of questions:

First question

In the Beagleboard xM, the USB OTG Base address is 0x480AB000.

What's the offset of the DMA registers in the Mentor Core USB controller? I have tried with 0x1000 but when I read the first register (DMAREVID) it gives me: 0x00206435. Unfortunately on the Technical Reference Manual there is not information on the DMA Registers (sprugn4m.pdf). What document should I use as reference for the registers of DMA?

Second question

What files in the Linux USB driver code correspond to the Beagleboard xM? So that I can use for reference.

Regards,

Esaias

over 14 years ago

0 Esaias Pech over 14 years ago

Prodigy 190 points

Anyone has any idea?

0 swami iyer over 14 years ago in reply to Esaias Pech

Prodigy 220 points

Typically TI-OTG related files reside under "drivers/usb/musb" directory.

regards

swami

0 Esaias Pech over 14 years ago in reply to swami iyer

Prodigy 190 points

Swami,

Thank you for your answer, I'm guessing I should pay closer attention to the am35x.c right?

So just to double check,

1. The AM37x uses the same CPPI DMA the OMAP L138 uses?

2. Is it the same offset as the OMAP L138?

Thanks

0 swami iyer over 14 years ago in reply to Esaias Pech

Prodigy 220 points

am35x.c is a platform related file and may not provide all the answers for you. A good place to start though. The generic portions are in other musb_ files. L138 would be good reference for CPPI DMA related functionality.

regards

swami

0 Esaias Pech over 14 years ago in reply to swami iyer

Prodigy 190 points

Thank you Swami,

1. I believe that the AM37x does not use PDR registers, right?

2. Is the the offset for the DMA Registers same for L138 and AM37x?

I ask because I tried getting DMAREVID in the AM37x and it just gives me garbage (I tried on an L138 and it works ok).

-Esaias

0 swami iyer over 14 years ago in reply to Esaias Pech

Prodigy 220 points

the usb driver (in Linux) for AM3517 is fully functional. Pl. refer to the port details for that platform for the base address offset. I do not have the related spec handy with me to guide you on that.

regards

swami

0 Esaias Pech over 14 years ago in reply to swami iyer

Prodigy 190 points

Thanks Swami! I will look into that.

0 Esaias Pech over 14 years ago in reply to Esaias Pech

Prodigy 190 points

Hi Swami,

Some others questions :)

1. What is the difference between the following files in the msub directory:

a) cppi_dma.c

b) cppi41_dma.c

c) musbhsdma.c

2. Which one is the one that the Beagleboard xM (DM37x) uses? It seems like on the musbhsdma.c just writes the address of the buffer and the count and that's about it?

3. I looked at the booting kernel log and it says:

musb_hdrc: USB OTG mode controller at fa0ab000 using DMA, IRQ 92

the "fa0ab000" is the USB OTG address?? On my driver I am using 0x480AB000 as the base address, what is the difference?

I really appreciate the fact you have replied to my previous questions, I am glad I get support from TI.

-Esaias

0 swami iyer over 14 years ago in reply to Esaias Pech

Prodigy 220 points

Esaias,

Pl. refer to cppi41_dma.c in conjunction with generic musb_* and {platform}.c files. musbhsdma.c is for OMAP platforms that use HSDMA (Mentor DMA) engine. AM3517 uses CPPI 4.1 DMA engine.

0xfa0ab000 might be the ioremapped address of the base address.

Pl. note that I do not work for TI and am extending the help based on my limited knowledge on this platform. As such if you need to work with TI engineer pl. contact them directly (through FAE??).

regards

swami

0 Esaias Pech over 14 years ago in reply to swami iyer

Prodigy 190 points

Thanks Swami, sorry, I thought you worked for TI, I never realized it says "Community Member".

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USB DMA DM37x