lkml.org 
[lkml]   [2018]   [Oct]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RESEND PATCH v5 0/9] extend PWM framework to support PWM modes
From
Date
On 14/09/2018 at 18:20, Nicolas Ferre wrote:
> Thierry,
>
> On 28/08/2018 at 15:01, Claudiu Beznea wrote:
>> Hi,
>>
>> Please give feedback on these patches which extends the PWM framework in
>> order to support multiple PWM modes of operations. This series is a rework
>> of [1] and [2].
>
> This series started with a RFC back on 5 April 2017 "extend PWM
> framework to support PWM modes". The continuous work starting with v2 of
> this series on January 12, 2018.
>
> Then Claudiu tried to address all comments up to v4 which didn't have
> any more reviews. He posted a v5 without comments since May 22, 2018.
> This series is basically a resent of the v5 (as said in the $subject).
>
> We would like to know what is preventing this series to be included in
> the PWM sub-system. Note that if some issue still remain with it, we are
> ready to help to solve them.
>
> Without feedback from you side, we fear that we would miss a merge
> window again for no obvious reason (DT part is Acked by Rob: patch 5/9).

3 weeks no news about my previous ping...

ping again!

> Best regards,
> Nicolas
>
>
>> The current patch series add the following PWM modes:
>> - PWM mode normal
>> - PWM mode complementary
>> - PWM mode push-pull
>>
>> Normal mode - for PWM channels with one output; output waveforms looks like
>> this:
>> __ __ __ __
>> PWM __| |__| |__| |__| |__
>> <--T-->
>>
>> Where T is the signal period
>>
>> Since PWMs with more than one output per channel could be used as one
>> output PWM the normal mode is the default mode for all PWMs (if not
>> specified otherwise).
>>
>> Complementary mode - for PWM channels with two outputs; output waveforms
>> for a PWM channel in complementary mode looks line this:
>> __ __ __ __
>> PWMH1 __| |__| |__| |__| |__
>> __ __ __ __ __
>> PWML1 |__| |__| |__| |__|
>> <--T-->
>>
>> Where T is the signal period.
>>
>> Push-pull mode - for PWM channels with two outputs; output waveforms for a
>> PWM channel in push-pull mode with normal polarity looks like this:
>> __ __
>> PWMH __| |________| |________
>> __ __
>> PWML ________| |________| |__
>> <--T-->
>>
>> If polarity is inversed:
>> __ ________ ________
>> PWMH |__| |__|
>> ________ ________ __
>> PWML |__| |__|
>> <--T-->
>>
>> Where T is the signal period.
>>
>> The PWM working modes are per PWM channel registered as PWM's capabilities.
>> The driver registers itself to PWM core a get_caps() function, in
>> struct pwm_ops, that will be used by PWM core to retrieve PWM capabilities.
>> If this function is not registered in driver's probe, a default function
>> will be used to retrieve PWM capabilities. Currently, the default
>> capabilities includes only PWM normal mode.
>>
>> PWM state has been updated to keep PWM mode. PWM mode could be configured
>> via sysfs or via DT. pwm_apply_state() will do the preliminary validation
>> for PWM mode to be applied.
>>
>> In sysfs, user could get PWM modes by reading mode file of PWM device:
>> root@sama5d2-xplained:/sys/class/pwm/pwmchip0/pwm2# ls -l
>> total 0
>> -r--r--r-- 1 root root 4096 Oct 9 09:07 capture
>> lrwxrwxrwx 1 root root 0 Oct 9 09:07 device -> ../../pwmchip0
>> -rw-r--r-- 1 root root 4096 Oct 9 08:42 duty_cycle
>> -rw-r--r-- 1 root root 4096 Oct 9 08:44 enable
>> --w------- 1 root root 4096 Oct 9 09:07 export
>> -rw-r--r-- 1 root root 4096 Oct 9 08:43 mode
>> -r--r--r-- 1 root root 4096 Oct 9 09:07 npwm
>> -rw-r--r-- 1 root root 4096 Oct 9 08:42 period
>> -rw-r--r-- 1 root root 4096 Oct 9 08:44 polarity
>> drwxr-xr-x 2 root root 0 Oct 9 09:07 power
>> lrwxrwxrwx 1 root root 0 Oct 9 09:07 subsystem -> ../../../../../../../../class/pwm
>> -rw-r--r-- 1 root root 4096 Oct 9 08:42 uevent
>> --w------- 1 root root 4096 Oct 9 09:07 unexport
>> root@sama5d2-xplained:/sys/class/pwm/pwmchip0/pwm2# cat mode
>> normal complementary [push-pull]
>>
>> The mode enclosed in bracket is the currently active mode.
>>
>> The mode could be set, via sysfs, by writing to mode file one of the modes
>> displayed at read:
>> root@sama5d2-xplained:/sys/class/pwm/pwmchip0/pwm2# echo normal > mode
>> root@sama5d2-xplained:/sys/class/pwm/pwmchip0/pwm2# cat mode
>> [normal] complementary push-pull
>>
>> The PWM push-pull mode could be usefull in applications like half bridge
>> converters.
>>
>> This series also add PWM modes support for Atmel/Microchip SoCs.
>>
>> Thank you,
>> Claudiu Beznea
>>
>> [1] https://www.spinics.net/lists/arm-kernel/msg580275.html
>> [2] https://lkml.org/lkml/2018/1/12/359
>>
>> Changes in v5:
>> - solved kbuild errors by removing dummy functions for case where
>> CONFIG_PWM is not defined; adopted this approach since the removed
>> function are used only when CONFIG_PWM is defined (in PWM core
>> and few drivers from drivers/pwm/ directory)
>>
>> Changes in v4:
>> - removed changes related to pwm_config() as per maintainer proposals
>> - added pwm_mode_get_valid() to retrieve a valid PWM mode fror PWM device
>> instead of using BIT(ffs(caps.mode) - 1) and changed drivers to use
>> pwm_mode_get_valid() instead of pwm_get_caps() + BIT(ffs(caps.mode) - 1)
>> (patches 2, 3, 4 from this series)
>> - renamed PWM_MODE() macro in PWMC_MODE() to avoid conflicts with
>> pwm-sun4i.c driver ('C' stands for capability)
>> - removed pwm_caps_valid() function
>> - renamed PWM_DTMODE_COMPLEMENTARY and PWM_DTMODE_PUSH_PULL macros in
>> PWM_MODE_COMPLEMENTARY and PWM_MODE_PUSH_PULL
>>
>> Changes in v3:
>> - removed changes related to only one of_xlate function for all PWM drivers
>> - switch to PWM capabilities per PWM channel nor per PWM chip
>> - squash documentation and bindings patches as requeted by reviewer
>> - introduced PWM_MODE(name) macro and used a bit enum for pwm modes
>> - related to DT bindings, used flags cell also for PWM modes
>> - updated of_xlate specific functions with "state->mode = mode;"
>> instructions to avoid pwm_apply_state() failures
>> - use available modes for PWM channel in pwm_config() by first calling
>> pwm_get_caps() to get caps.modes
>> - use loops through available modes in mode_store()/mode_show() and also in
>> of_pwm_xlate_with_flags() instead of "if else" instructions; in this way,
>> the addition of a new mode is independent of this code sections
>> - use DTLI=1, DTHI=0 register settings to obtain push-pull mode waveforms
>> for Atmel/Microchip PWM controller.
>>
>> Changes in v2:
>> - remove of_xlate and of_pwm_n_cells and use generic functions to pharse DT
>> inputs; this is done in patches 1, 2, 3, 4, 5, 6, 7 of this series; this will
>> make easy the addition of PWM mode support from DT
>> - add PWM mode normal
>> - register PWM modes as capabilities of PWM chips at driver probe and, in case
>> driver doesn't provide these capabilities use default ones
>> - change the way PWM mode is pharsed via DT by using a new input for pwms
>> binding property
>>
>>
>> Claudiu Beznea (9):
>> pwm: extend PWM framework with PWM modes
>> pwm: clps711x: populate PWM mode in of_xlate function
>> pwm: cros-ec: populate PWM mode in of_xlate function
>> pwm: pxa: populate PWM mode in of_xlate function
>> pwm: add PWM modes
>> pwm: atmel: add pwm capabilities
>> pwm: add push-pull mode support
>> pwm: add documentation for pwm push-pull mode
>> pwm: atmel: add push-pull mode support
>>
>> Documentation/devicetree/bindings/pwm/pwm.txt | 11 ++-
>> Documentation/pwm.txt | 42 ++++++++-
>> drivers/pwm/core.c | 125 +++++++++++++++++++++++++-
>> drivers/pwm/pwm-atmel.c | 118 +++++++++++++++++-------
>> drivers/pwm/pwm-clps711x.c | 10 ++-
>> drivers/pwm/pwm-cros-ec.c | 1 +
>> drivers/pwm/pwm-pxa.c | 1 +
>> drivers/pwm/sysfs.c | 61 +++++++++++++
>> include/dt-bindings/pwm/pwm.h | 2 +
>> include/linux/pwm.h | 64 +++++++++++++
>> 10 files changed, 395 insertions(+), 40 deletions(-)
>>
>
>


--
Nicolas Ferre

\
 
 \ /
  Last update: 2018-10-03 14:50    [W:0.258 / U:7.784 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site