Hello Alan, Thank you for your answer. >> 1. The timing of update a Descriptor is after transfer Completion interrupt. Is my understanding correct? > Okay, the answer is No. The qTD is updated _before_ the completion interrupt, not _after_. I understood. >> 2. Is there the status to confirm in descriptor before updating a Descriptor elsewhere? > I don't understand this question. Please give more details about what you want to know. I want to know that the timing of data transfer buffer (Buffer Pointer (Page x)) to another region. After generated Completion interrupt, can the buffer data move another region by CPU or DMA soon? (Does the CPU need to know all received data is in DDR region another way? ) Thank you Regards Takasugi ********************************************* Texas Instruments Japan Sales and Marketing Yokohama office Takasugi Hirokazu <takasugi@xxxxxx> TEL:03-4331-7124 FAX:045-453-9326 ********************************************* -----Original Message----- From: Alan Stern [mailto:stern@xxxxxxxxxxxxxxxxxxx] Sent: Monday, September 19, 2011 1:29 AM To: Takasugi, Hirokazu Cc: linux-usb@xxxxxxxxxxxxxxx Subject: RE: DM3725 EHCI HOST controller descriptor update timing On Sun, 18 Sep 2011, Takasugi, Hirokazu wrote: > Hello Alan, > > Thank you for your response. > > >I still don't know what descriptor you're talking about. The qTD? The QH descriptor? Something else? > The your answer is the qTD. > > >Maybe _it_ doesn't need to know the descriptor type -- but if I'm > >going to answer your question then _I_ need to know! :-) > I understood. i want to know the reference of these sequence. > > > 1. The timing of update a Descriptor is after transfer Completion interrupt. Is my understanding correct? Okay, the answer is No. The qTD is updated _before_ the completion interrupt, not _after_. > > > 2. Is there the status to confirm in descriptor before updating a Descriptor elsewhere? I don't understand this question. Please give more details about what you want to know. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
