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.thebaudeau@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