On Wednesday 16 of July 2014 23:41:57 Simon Glass wrote: > Hi Pavel, > > On 15 July 2014 02:26, Pavel Herrmann <morpheus.i...@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 USB > >> bus + > >> + sata (UCLASS_SATA) > >> + flash (UCLASS_FLASH_STORAGE) - parent data/methods defined by > >> SATA > >> 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. > > as a side note, flash is a bit tricky here, since USB and SATA do not > > provide you with "flash-like" interface even for flash-based devices, but > > instead have a disk-like interface, which is simpler (does not give you > > the ability to control bad block management, among other things). > > Another reason why the example is poor - I was more thinking of flash > as a disk than a raw NAND device. > > Regards, > Simon regards Pavel Herrmann _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
