Hi Stefan, > Hi Lukasz, > > On 2016-10-04 00:48, Lukasz Majewski wrote: > > Dear Bhuvanchandra, > > > > Thank you for your effort to send those patches to ML. > > > >> Changes since v2: > >> > >> - Picked the stalled patchset[1] from Lothar Wassmann which adds > >> the basic support for polarity control on imx-pwm driver and adds > >> backward compatibility support for devices which does not have > >> polarity control feature. > >> > >> Changes since Lothars v6: > >> > >> - Squash Lukasz patch[2]. > >> > >> [1] http://thread.gmane.org/gmane.linux.pwm/1621 > >> [2] https://www.spinics.net/lists/arm-kernel/msg530818.html > >> > >> Bhuvanchandra DV (3): > >> arm: dts: imx7: Update #pwm-cells for PWM polarity control > >> arm: dts: imx7-colibri: Use pwm polarity control > >> arm: dts: imx7-colibri: Use enable-gpios for BL_ON > >> > >> Lothar Wassmann (3): > >> pwm: print error messages with pr_err() instead of pr_debug() > >> pwm: core: make the PWM_POLARITY flag in DTB optional > >> pwm: imx: support output polarity inversion > > > > For some reason this patchset works differently than the one > > developed by Lothar. > > > > The difference is with the brightness level control. > > > > My brightness definition in DTS: > > > > pwms = <&pwm2 0 5000000 PWM_POLARITY_INVERTED>; > > > > brightness-levels = < 0 1 2 3 4 5 6 > > 7 8 9 > > > > .. ............ > > 250 251 252 253 254 255>; > > default-brightness-level = <50>; > > enable-gpios = <&gpio1 2 GPIO_ACTIVE_LOW>; > > > > If you are using something else than i.MX 7 you also want to update > the SoC level device tree, specifically change the pwm-cells property: > #pwm-cells = <3>; Good point. However, it is declared elsewhere (with pwm2 node) &pwm2 { #pwm-cells = <3>; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_pwm2>; status = "okay"; }; > > > > When I go to the backlight sysfs entry: > > > > cd /sys/devices/soc0/backlight/backlight/backlight > > > > It seems like the brightness level control is inverted - i.e. > > 'echo 20 > brightness" makes picture on the screen very bright, and > > 'echo 200 > brightness' makes the picture diminish. > > > > With my "internal" patches the situation is opposite (and I've > > checked it with my HW connections). > > Just to check whether the driver actually applies the polarity you can > add a #define DEBUG at the top of the driver (drivers/pwm/pwm-imx.c) > and pass ignore_loglevel as kernel command line. This should give you > "PWM supports output inversion" at startup and a "... polarity set > to .." message whenever the polarity is set. The problem is with the Bhuvanchandra original patch. I will point it out when replying to original patch. Thanks for support, Łukasz Majewski > > -- > Stefan > > > > > Could you check on your setup if similar situation takes place? I > > mean if the brightness control works as expected? > > > > Thanks in advance, > > Łukasz Majewski > > > >> > >> Documentation/devicetree/bindings/pwm/imx-pwm.txt | 6 +-- > >> arch/arm/boot/dts/imx7-colibri.dtsi | 12 +++++- > >> arch/arm/boot/dts/imx7s.dtsi | 8 ++-- > >> drivers/pwm/core.c | 31 > >> ++++++++------ drivers/pwm/pwm-imx.c | > >> 51 +++++++++++++++++++++-- 5 files changed, 83 insertions(+), 25 > >> deletions(-) > >>
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