Hi Fabio, On Sunday, September 29, 2013 8:58:09 PM, Fabio Estevam wrote: > Hi Benoît, > > On Sun, Sep 29, 2013 at 3:50 PM, Benoît Thébaudeau > <benoit.thebaud...@advansee.com> wrote: > > > Can you test again without any GPIO patch, but with SION set for this pin > > in the > > IOMUXC? According to the reference manual, SION not being set in the IOMUXC > > is > > the only reason that would prevent PSR from reading the pin level in GPIO > > output > > mode. > > Yes, from the feedback from a colleague the SION bit plays a role here: > > "The RM does not describe this clear. The fact should be: > > PSR for input, DR for output. > PSR can be for output only when SION bit is set (now PSR = DR). "
Yes, that's well explained in the i.MX6Q RM: " 28.4.2.1 GPIO Read Mode The programming sequence for reading input signals should be as follows: 1. Configure IOMUX to select GPIO mode (Via IOMUX Controller (IOMUXC) ). 2. Configure GPIO direction register to input (GPIO_GDIR[GDIR] set to 0b). 3. Read value from data register/pad status register. [...] NOTE While the GPIO direction is set to input (GPIO_GDIR = 0), a read access to GPIO_DR does not return GPIO_DR data. Instead, it returns the GPIO_PSR data, which is the corresponding input signal value. 28.4.2.2 GPIO Write Mode The programming sequence for driving output signals should be as follows: 1. Configure IOMUX to select GPIO mode (Via IOMUXC), also enable SION if need to read loopback pad value through PSR 2. Configure GPIO direction register to output (GPIO_GDIR[GDIR] set to 1b). 3. Write value to data register (GPIO_DR). " So: - in input mode: DR = PSR = pin, - in output mode: DR is applied to the pin, and the pin level can be read back through PSR if SION is set (i.e. PSR = DR unless there is a hardware conflict). Hence, gpio_get_value() should be left unchanged (using PSR in all cases), and SION should be set for all GPIOs in the i.MX6 pin definition header files. Best regards, Benoît _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
