On Tue, 2013-11-19 at 16:32 +0100, Anatolij Gustschin wrote: > On Fri, 15 Nov 2013 15:16:29 +0800 > Liu Gang <gang....@freescale.com> wrote: > > > For MPC8572/MPC8536, the status of GPIOs defined as output > > cannot be determined by reading GPDAT register, so the code > > use shadow data register instead. But if the input pins are > > asserted high, they will always read high due to the shadow > > data, even if the pins are set to low. > > Could you please add a better description of the problem? > I'm having some difficulties to understand the last sentence > above. Does the issue appear if some pins were configured as > inputs and were asserted high before booting the kernel, and > therefore the shadow data has been initialized with these pin > values? > > Or does the issue appear if some pin has been configured as output > first and has been set to the high value, then reconfigured as > input? Now reading the pin state will always return high even > if the actual pin state is low? > > It seems the issue will appear in both cases. If so, please add > this information to the commit message. > Yes, you are right. I'll updated the description more clear.
> > val = in_be32(mm->regs + GPIO_DAT) & ~in_be32(mm->regs + GPIO_DIR); > > + mpc8xxx_gc->data &= in_be32(mm->regs + GPIO_DIR); > > we can reduce one in_be32() call here, i.e. > > u32 out_mask; > ... > out_mask = in_be32(mm->regs + GPIO_DIR); > val = in_be32(mm->regs + GPIO_DAT) & ~out_mask; > mpc8xxx_gc->data &= out_mask; > > > return (val | mpc8xxx_gc->data) & mpc8xxx_gpio2mask(gpio); > > } > > Thanks, > > Anatolij > Granted, it will be better to reduce one in_be32() call. I'll improve the method based on your and Scott's comments. Thanks Liu Gang _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
