Hello Michal, On Fri, Nov 23, 2018 at 03:15:11PM +0000, Vokáč Michal wrote: > On 22.11.2018 20:03, Uwe Kleine-König wrote: > > On Thu, Nov 22, 2018 at 04:46:39PM +0000, Vokáč Michal wrote: > >> On 22.11.2018 17:23, Uwe Kleine-König wrote: > >>> So I'd expect this to really work on i.MX6 but not the earlier SoCs > >>> without a gpio specifier. > >> > >> Maybe you would expect it to work but I already tested and measured > >> that weeks ago ;) It did not work. > > > > Which pin/gpio do we talk about? Which i.MX6 variant did you test this > > on? (Assuming i.MX6D or i.MX6Q and PAD_DISP0_DATA09, did you try setting > > > > IOMUXC_SW_MUX_CTL_PAD_DISP0_DATA09 (0x020E0194) = 0x00000005 > > IOMUXC_SW_PAD_CTL_PAD_DISP0_DATA09 (0x020E04A8) = 0x0000b080 > > > > and then play with GPIO 4.30 direction and output value?) > > My test setup is as follows: > - SoC is i.MX6DL or i.MX6S - I have three board variants in total. > - Pin used for PWM/GPIO is PAD_GPIO9. > - The pin is not connected to any circuit. Just a test point. > - pinctrl setup in DT: > - for "pwm": > - fsl,pins = <MX6QDL_PAD_GPIO_9__PWM1_OUT 0x8> > - IOMUXC_SW_MUX_CTL_PAD_GPIO09 = 0x00000004 > - IOMUXC_SW_PAD_CTL_PAD_GPIO09 = 0x00000008 > > - for "gpio": > - fsl,pins = <MX6QDL_PAD_GPIO_9__GPIO1_IO09 0xb000> > - IOMUXC_SW_MUX_CTL_PAD_GPIO09 = 0x00000005 > - IOMUXC_SW_PAD_CTL_PAD_GPIO09 = 0x0000b000 FTR: I suggested 0x0000b080 here, but 0x0000b000 is just fine. > Test scenario: > > - In bootloader configure the pin as GPIO output, set it LOW (0V). > I set it LOW to start in the oposite state than I want to end up in. > - Boot Linux > - Use sysfs to configure the PWM to produce some signal. > - In the PWM driver select the "pwm" pinctrl state. > - Measure the output - expected waveform on the scope. > - Use sysfs to stop the PWM "echo 0 > /sys/class/pwm/pwmchip0/pwm0/enable° > - In the PWM driver select the "gpio" pinctrl state. > - Then in the PWM driver: > > a) non-working variant > - Do not request the GPIO - so do not touch its pad control reg. > It is set as output from the bootloader, data register = 0. > - Measure voltage on the output > - against GND = 0V > - against VCC = 0V > - Measure resistance against VCC: Hi-Z > > The pin is in Hi-Z mode. That is fine but that does not satisfy any > logic level. > > b) working variant > - Request the GPIO, configure it as input. > - Measure voltage on the output > - against GND = VCC (3.3V) > - against VCC = 0V > - Measure resistance against VCC = 91.1kOhm > > The pull-up is active. Thanks for your detailed test. So DSE = 0 doesn't work as I (and I think Lothar) expected. @Lothar: if Michal did something different than you expected, please tell us with a few more details. > I can repeat the results on both i.MX6DL and i.MX6S on pwm1 and pwm4. > All pull-up and pull-down combinations gave me the expected results > only if the pin is configured as input. So if I repeat the test and > do not touch the pin in bootloader at all, it works as well even if > I do not request/configure the GPIO in the PWM driver. OK. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
