About fsl_ep_queue() of arcotg_udc.c in i.MX6SDL jb4.2.2_1.1.0.

[keitanagashima]

Dear Sir or Madam,

Hello.

I have a question about fsl_ep_queue() of arcotg_udc.c in i.MX6SDL jb4.2.2_1.1.0.

[Issue]

See attached file : Issue Sequence.docx

[Test result]

Specifies 16 KB in req->length : No problem

Specifies 32 KB in req->length : The issue occured

Specifies 64 KB in req->length : The issue occured

[Question]

Is there limitation on the 16 KB upper limit in the argument req->length of fsl_ep_queue()?

Keita

[keitanagashima]

Could someone follow up the question?

Keita

[gusarambula]

Yes, the maximum recommended transfer is set to 16Kbytes due to a limitation on the endpoint transfer descriptor.

[keitanagashima]

Dear gusarambula,

Let me clarify your answer.

Which case is right?

[Case.1]

- 16KBytes is the upper limit which it is possible to set.

- When setting the value which is bigger than 16KB, the problem occurs.

[Case.2]

- You recommends to set the value which is smaller than 16KB.

- But freescale has never confirmed operation, when setting the value which is bigger than 16KB.

[Case.3]

- You recommends to set the value which is smaller than 16KB

- When setting the value which is bigger than 16KB, there is not a problem in case of operation.

But, it isn't possible to expect the improvement of the performance.

( Because the upper limit of end point transfer descriptor is 16KBytes )

[Case.4]

Is your answer the other meaning?

Keita

[gusarambula · Accepted solution]

I apologize for nor being more concise on my answer.

The first case is right. 16Kbytes is the maximum transfer regardless of starting buffer alignment. That’s why it’s the recommended maximum.

[keitanagashima]

Dear gusarambula,

Thank you!

Keita