Re: [PATCH v3 06/10] pwm: add PWM modes

[Claudiu Beznea]

On 22.02.2018 19:28, Andy Shevchenko wrote:
> On Thu, Feb 22, 2018 at 2:01 PM, Claudiu Beznea
>  wrote:
>> Add PWM normal and complementary modes.
> 
>> +- PWM_DTMODE_COMPLEMENTARY: PWM complementary working mode (for PWM
>> +channels two outputs); if not specified, the default for PWM channel will
>> +be used
> 
> What DT stands for?
It stands for Device Tree. It remained this way from the previous version. In
the previous version I had modes described in an enum, to be used by PWM core,
as follows:
enum pwm_mode {
PWM_MODE_NORMAL,
PWM_MODE_COMPLEMENTARY,
};

and, to avoid conflict b/w these defines and the one from
include/dt-bindings/pwm/pwm.h I introduced this DT in the define names from
dt-bindings. But now the DT might be removed since I've changed the way the PWM
mode is identified in PWM core. I will remove the DT in the next version, if not
requested otherwise.

Thank you,
Claudiu Benea
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[PATCH v3 06/10] pwm: add PWM modes

[Claudiu Beznea]

Add PWM normal and complementary modes.

Signed-off-by: Claudiu Beznea 
---
 Documentation/devicetree/bindings/pwm/pwm.txt |  9 +++--
 Documentation/pwm.txt | 26 +++---
 include/dt-bindings/pwm/pwm.h |  1 +
 3 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt 
b/Documentation/devicetree/bindings/pwm/pwm.txt
index 8556263b8502..c2b4b9ba0e3f 100644
--- a/Documentation/devicetree/bindings/pwm/pwm.txt
+++ b/Documentation/devicetree/bindings/pwm/pwm.txt
@@ -46,11 +46,16 @@ period in nanoseconds.
 Optionally, the pwm-specifier can encode a number of flags (defined in
 ) in a third cell:
 - PWM_POLARITY_INVERTED: invert the PWM signal polarity
+- PWM_DTMODE_COMPLEMENTARY: PWM complementary working mode (for PWM
+channels two outputs); if not specified, the default for PWM channel will
+be used
 
-Example with optional PWM specifier for inverse polarity
+Example with optional PWM specifier for inverse polarity and complementary
+mode:
 
bl: backlight {
-   pwms = < 0 500 PWM_POLARITY_INVERTED>;
+   pwms = < 0 500
+   (PWM_DTMODE_COMPLEMENTARY | PWM_POLARITY_INVERTED)>;
pwm-names = "backlight";
};
 
diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt
index 8fbf0aa3ba2d..59592f8cc381 100644
--- a/Documentation/pwm.txt
+++ b/Documentation/pwm.txt
@@ -61,9 +61,9 @@ In addition to the PWM state, the PWM API also exposes PWM 
arguments, which
 are the reference PWM config one should use on this PWM.
 PWM arguments are usually platform-specific and allows the PWM user to only
 care about dutycycle relatively to the full period (like, duty = 50% of the
-period). struct pwm_args contains 2 fields (period and polarity) and should
-be used to set the initial PWM config (usually done in the probe function
-of the PWM user). PWM arguments are retrieved with pwm_get_args().
+period). struct pwm_args contains 3 fields (period, polarity and mode) and
+should be used to set the initial PWM config (usually done in the probe
+function of the PWM user). PWM arguments are retrieved with pwm_get_args().
 
 Using PWMs with the sysfs interface
 ---
@@ -110,6 +110,26 @@ channel that was exported. The following properties will 
then be available:
- 0 - disabled
- 1 - enabled
 
+  mode
+Get/set PWM channel working mode.
+
+Normal mode - for PWM channels with one output; this should be the
+default working mode for every PWM channel; output waveforms looks
+like this:
+ ________
+PWM   __|  |__|  |__|  |__|  |__
+<--T-->
+
+Complementary mode - for PWM channels two outputs; output waveforms
+looks line this:
+ ________
+PWMH1 __|  |__|  |__|  |__|  |__
+  __________
+PWML1   |__|  |__|  |__|  |__|
+<--T-->
+
+Where T is the signal period.
+
 Implementing a PWM driver
 -
 
diff --git a/include/dt-bindings/pwm/pwm.h b/include/dt-bindings/pwm/pwm.h
index ab9a077e3c7d..b4d61269aced 100644
--- a/include/dt-bindings/pwm/pwm.h
+++ b/include/dt-bindings/pwm/pwm.h
@@ -11,5 +11,6 @@
 #define _DT_BINDINGS_PWM_PWM_H
 
 #define PWM_POLARITY_INVERTED  (1 << 0)
+#define PWM_DTMODE_COMPLEMENTARY   (1 << 1)
 
 #endif
-- 
2.7.4

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Re: [PATCH v3 06/10] pwm: add PWM modes

[Andy Shevchenko]

On Thu, Feb 22, 2018 at 2:01 PM, Claudiu Beznea
 wrote:
> Add PWM normal and complementary modes.

> +- PWM_DTMODE_COMPLEMENTARY: PWM complementary working mode (for PWM
> +channels two outputs); if not specified, the default for PWM channel will
> +be used

What DT stands for?

-- 
With Best Regards,
Andy Shevchenko
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