Device including means for transferring information indicating whether or not the device supports DMA
View Patent ↗A device for attachment to a host for serial data communication including means for transferring to the host a predetermined data structure indicating whether or not the device supports direct memory access.
1. A device for attachment to a host for serial data communication comprising:
a memory configured to store a predetermined data structure that indicates whether or not the device supports direct memory access; and
an interface for enabling the transfer from the device to the host of the predetermined data structure.
2. A device as claimed in claim 1 , wherein the interface is responsive to a request from the host.
3. A device as claimed in claim 1 , wherein the predetermined data structure is one of a plurality of data structures transferred at one time to the host.
4. A device as claimed in claim 1 , wherein the device is a USB device and the predetermined data structure is a descriptor.
5. A device as claimed in claim 4 , wherein the descriptor is a non-standard descriptor.
6. A device as claimed in claim 4 , wherein the predetermined data structure extends a preceding descriptor.
7. A device as claimed in claim 4 , wherein the predetermined data structure is transferred during the device enumeration.
8. A host for attachment to a device for serial data communication comprising:
a controller for receiving a data structure from the device, and a processor operable to identify a transferred data structure as a predetermined data structure, that indicates that the device supports direct memory access.
9. A host as claimed in claim 8 , wherein the transfer means is arranged to request the device to send at least the predetermined data structure.
10. A host as claimed in claim 8 , wherein the predetermined data structure is one of a plurality of data structures transferred at one time to the host.
11. A host as claimed in claim 8 wherein the host is a USB host and the predetermined data structure is a descriptor.
12. A host as claimed in claim 11 , wherein the descriptor is a non-standard descriptor.
13. A host as claimed in claim 11 , wherein the predetermined data structure extends a previously transferred descriptor.
14. A host as claimed in claim 8 , where the processor is further operable to allocate tasks relating to data transfer from/to the device in dependence upon the content of the predetermined data structure.
15. A host as claimed in claim 11 , wherein the predetermined data structure is transferred during the enumeration of the device by the host.
16. A system comprising a host, a device comprising a predetermined data structure, and a serial data interconnect between the host and device, the system further comprising:
an interface for transferring, from the device to the host via the serial data interconnect, a predetermined data structure indicating whether or not the device supports direct memory access.
17. A system as claimed in claim 16 wherein the host is arranged to request the device to send at least the predetermined data structure.
18. A system as claimed in claim 16 wherein the device is arranged to transfer the predetermined data structure in response to a request from the host.
19. A system as claimed in claim 16 wherein the device is a USB device, the host is a USB host and the predetermined data structure is a descriptor.
20. A method of attaching a device to a host for serial data communication comprising:
transferring from the device to the host, a predetermined data structure that indicates whether or not the device supports direct memory access.
21. A method as claimed in claim 19 wherein the device transfers the predetermined data structure to the host in response to a request from the host.
22. A method as claimed in claim 19 wherein the device is a USB device, the host is a USB host and the predetermined data structure is a descriptor.