On Tuesday 15 December 2015 17:31:22 Thierry Reding wrote: > On Mon, Dec 14, 2015 at 12:39:44PM +0100, Arnd Bergmann wrote: > > On Wednesday 18 November 2015 17:56:22 Andy Yan wrote: > > > rockchip platform have a protocol to pass the kernel reboot > > > mode to bootloader by some special registers when system reboot. > > > By this way the bootloader can take different action according > > > to the different kernel reboot mode, for example, command > > > "reboot loader" will reboot the board to rockusb mode, this is > > > a very convenient way to get the board enter download mode. > > > > > > Signed-off-by: Andy Yan <andy.yan@xxxxxxxxxxxxxx> > > > > Adding John Stultz to Cc > > > > I just saw this thread pop up again, and had to think of John's recent > > patch to unify this across platforms. > > > > John, can you have a look at this driver too, and see how it fits in? > > I think this is yet another variant, using an MMIO register rather than > > RAM (as HTC / NVIDIA does) or SRAM (as Qualcomm does), but otherwise > > it conceptually fits in with what you had. > > FWIW, Tegra typically does use an MMIO register as well. See > drivers/soc/tegra/pmc.c:tegra_pmc_restart_notify(). I don't know what > HTC does, but if it's writing somewhere in RAM it isn't using the > standard way of resetting the SoC. There's early boot ROM code which I > think evaluates the PMC_SCRATCH0 register on Tegra to determine which > mode to boot into. That's before even any firmware gets the chance of > doing anything. HTC apparently uses a separate RAM area to pass the reboot reason, and they have a driver to store that, which is separate from the driver that they use for actually rebooting the machine. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
