Hi Pavel,
On 17 July 2014 01:09, Pavel Herrmann morpheus.ibis@gmail.com wrote:
On Wednesday 16 of July 2014 23:41:57 Simon Glass wrote:
Hi Pavel,
On 15 July 2014 02:26, Pavel Herrmann morpheus.ibis@gmail.com wrote:
Hi
On Tuesday 08 of July 2014 21:38:16 Simon Glass wrote:
...
+Note that the information that controls this behaviour is in the bus's +driver, not the child's. In fact it is possible that child has no knowledge +that it is connected to a bus. The same child device may even be used on two +different bus types. As an example. the 'flash' device shown above may also +be connected on a SATA bus or standalone with no bus:
- xhci_usb (UCLASS_USB)
flash (UCLASS_FLASH_STORAGE) - parent data/methods defined by USBbus +
- sata (UCLASS_SATA)
flash (UCLASS_FLASH_STORAGE) - parent data/methods defined bySATA bus +
- flash (UCLASS_FLASH_STORAGE) - no parent data/methods (not on a bus)
this is not the best example, since the driver actually needs to have an idea what parent bus it is connected to, as it should use the parents driver.ops to communicate with the device.
Yes, it's not a good example.
the better (more realistic) version would show that the same device would operate under various xhci_usb, ohci_usb and ehci_usb busses, which might very well have different parent_priv structure (for example, ohci_usb would probably not store maximum speed supported by the device, since the bus only has the basic one)
They still use the parent driver ops, but now they are all the same? Do you mean that the uclass would be the same for each bus?
Yes, I imagine the uclass for USB host controller would the same, not depending on the speed of the controller.
OK, but there is no requirement for the child data to be the same for each USB device. Each device has its own child data structure - this is not defined by the uclass but by the udevice.
Regards, Simon