Hi Greg and all, Currently I am working on USB Host which is plain USB host hardware (which does not adhere to any of the spec - OHCI/ etc - provides plain registers interfaces to manage data flow). I have ported NuttX USB Host for Mass storage (MSC) and it is working well for basic testing like, mount/ copy files/ remove files etc.
As part of throughput measurement, I am trying to copy huge files with size around 200+ KB. Some times, copy succeeds and some times code waits indefinitely. On looking at the USB analyzer logs, I see below pattern. 1. Upper layer (usbhost_storage.c) keeps sending CBW (Command Block Wrapper), Data (always 512 bytes) and CSW (Command Status Wrapper) in usbhost_read() and usbhost_write() functions. 2. When I see the issue, it is due to a. Previous block is transmitted. b. Upper layer (usbhost_storage.c) is trying to transfer the next block and sends the CBW (31 bytes) c. Device (using normal pendrive) seems to be busy (possibly it is managing the internal details with previously received data) and there is no response. d. My USB Host device waits for turn around time and raises interrupt Not Ready (NRDY). 3. With this scenario, I am trying to find out, is there any way, driver can intimate the upper layer that device is busy/ not responding, so that upper layer can retry sending the data? I looked at ..nuttx-8.2\include\errno.h and could not figure out which one is the correct error to be returned for usbhost_storage.c so that re-try can happen (EBUSY seems to be ideal, but I did not see the retry after returning this EBUSY error). Please let me know if you have any suggestion/ comments on handling this kind of device behavior. With best regards, Phani. >
