On 03/05/11 19:08, Greg KH wrote: > On Sat, Apr 30, 2011 at 11:56:25AM +0200, Jan Andersson wrote: >> The two first HC capability registers (CAPLENGTH and HCIVERSION) >> are defined as one 8-bit and one 16-bit register. Most HC >> implementations have selected to treat these registers as part >> of a 32-bit register, giving the same layout for both big and >> small endian systems. >> >> This patch adds a new quirk, big_endian_capbase, to support >> controllers with big endian register interfaces that treat >> HCIVERSION and CAPLENGTH as individual registers. >> >> Signed-off-by: Jan Andersson <jan@xxxxxxxxxxx> >> Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> >> --- >> This solution has previously been discussed on linux-usb [1] where >> Alan Stern described the problem better: >> >> As an example for the sake of argument, let's suppose that CAPLENGTH is >> 0x03 and HCIVERSION is 0x67. If the controller is in little-endian mode, >> this means that the memory-mapped registers will contain the following >> bytes (starting from offset 0): 0x03 0x00 0x07 0x06. Any CPU, whether >> little-endian or big-endian, using ehci_readl() would obtain 0x06070003, >> and the macros would then yield the correct values. >> >> Now suppose the controller is in big-endian mode. The memory-mapped >> registers will contain the bytes: 0x03 0x00 0x06 0x07. Any CPU, whether >> little-endian or big-endian, using ehci_readl() would obtain 0x03000607, >> which of course doesn't work with the HC_LENGTH and HC_VERSION macros >> >> [1] http://marc.info/?l=linux-usb&m=126421978732228&w=2 >> >> Changes for V2: >> * Add acked-by AS >> * Fixup prefixes in patch description >> * Fix build error in early/ehci-dbgp.c after comment from Greg KH > > Nope, I still get the following build error: > > CC drivers/usb/early/ehci-dbgp.o > drivers/usb/early/ehci-dbgp.c: In function âearly_dbgp_initâ: > drivers/usb/early/ehci-dbgp.c:895:2: error: implicit declaration of function âehci_big_endian_capbaseâ > drivers/usb/early/ehci-dbgp.c:895:26: error: âehciâ undeclared (first use in this function) > drivers/usb/early/ehci-dbgp.c:895:26: note: each undeclared identifier is reported only once for each function it appears in > make[3]: *** [drivers/usb/early/ehci-dbgp.o] Error 1 > > > Care to try again? > Yes, sloppiness on my part. I suppose the best solution is to define a local variant of HC_LENGTH in ehci-dbgp.c since the ehci struct is not available. I will send a new version. Apologies for wasting your time. Best regards, Jan -- 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
