[v2,02/16] pwm: pxa: update documentation regarding pwm-cells

Message ID 1515766983-15151-3-git-send-email-claudiu.beznea@microchip.com
State Changes Requested
Headers show
Series
  • extend PWM framework to support PWM modes
Related show

Commit Message

Claudiu Beznea Jan. 12, 2018, 2:22 p.m.
pwm-cells should be at least 2 to provide channel number and period value.

Cc: Mike Dunn <mikedunn@newsguy.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 Documentation/devicetree/bindings/pwm/pxa-pwm.txt | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Rob Herring Jan. 19, 2018, 10:30 p.m. | #1
On Fri, Jan 12, 2018 at 04:22:49PM +0200, Claudiu Beznea wrote:
> pwm-cells should be at least 2 to provide channel number and period value.
> 
> Cc: Mike Dunn <mikedunn@newsguy.com>
> Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
> ---
>  Documentation/devicetree/bindings/pwm/pxa-pwm.txt | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pxa-pwm.txt b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
> index 5ae9f1e3c338..a0e20edeeebc 100644
> --- a/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
> +++ b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
> @@ -10,7 +10,7 @@ Required properties:
>    Note that one device instance must be created for each PWM that is used, so the
>    length covers only the register window for one PWM output, not that of the
>    entire PWM controller.  Currently length is 0x10 for all supported devices.
> -- #pwm-cells: Should be 1.  This cell is used to specify the period in
> +- #pwm-cells: Should be 2.  This cell is used to specify the period in
>    nanoseconds.

What's the new cell? channel? Does the PXA PWM have more than one 
channel? If not, then you shouldn't add a cell.

Rob
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Claudiu Beznea Jan. 22, 2018, 8:47 a.m. | #2
On 20.01.2018 00:30, Rob Herring wrote:
> On Fri, Jan 12, 2018 at 04:22:49PM +0200, Claudiu Beznea wrote:
>> pwm-cells should be at least 2 to provide channel number and period value.
>>
>> Cc: Mike Dunn <mikedunn@newsguy.com>
>> Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
>> ---
>>  Documentation/devicetree/bindings/pwm/pxa-pwm.txt | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/pwm/pxa-pwm.txt b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
>> index 5ae9f1e3c338..a0e20edeeebc 100644
>> --- a/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
>> +++ b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
>> @@ -10,7 +10,7 @@ Required properties:
>>    Note that one device instance must be created for each PWM that is used, so the
>>    length covers only the register window for one PWM output, not that of the
>>    entire PWM controller.  Currently length is 0x10 for all supported devices.
>> -- #pwm-cells: Should be 1.  This cell is used to specify the period in
>> +- #pwm-cells: Should be 2.  This cell is used to specify the period in
>>    nanoseconds.
> 
> What's the new cell? channel? Does the PXA PWM have more than one 
> channel? If not, then you shouldn't add a cell.
The new cell had to be period, to have a generic OF function in the kernel,
to parse the pwms bindings for all PWMs, something like
pwms=<pwm channel-number pwm-period>. After several discussions on this
series, I found that old DT binaries must be compatible with latest kernel
version and this series doesn't guarantee this. So I will drop this change
in next version.

Thank you,
Claudiu Beznea
> 
> Rob
> 
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Patch

diff --git a/Documentation/devicetree/bindings/pwm/pxa-pwm.txt b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
index 5ae9f1e3c338..a0e20edeeebc 100644
--- a/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
+++ b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
@@ -10,7 +10,7 @@  Required properties:
   Note that one device instance must be created for each PWM that is used, so the
   length covers only the register window for one PWM output, not that of the
   entire PWM controller.  Currently length is 0x10 for all supported devices.
-- #pwm-cells: Should be 1.  This cell is used to specify the period in
+- #pwm-cells: Should be 2.  This cell is used to specify the period in
   nanoseconds.
 
 Example PWM device node:
@@ -18,13 +18,13 @@  Example PWM device node:
 pwm0: pwm@40b00000 {
 	compatible = "marvell,pxa250-pwm";
 	reg = <0x40b00000 0x10>;
-	#pwm-cells = <1>;
+	#pwm-cells = <2>;
 };
 
 Example PWM client node:
 
 backlight {
 	compatible = "pwm-backlight";
-	pwms = <&pwm0 5000000>;
+	pwms = <&pwm0 0 5000000>;
 	...
 }