[v3,1/2] dt-bindings: serial: Document CTS/RTS gpios in STM32 UART

From: Manivannan Sadhasivam <mani@kernel.org>

Document the use of CTS/RTS gpios for flow control in STM32 UART
controller. These properties can be used instead of 'st,hw-flow-ctrl'
for making use of any gpio pins for flow control instead of dedicated
pins. It should be noted that both CTS/RTS and 'st,hw-flow-ctrl'
properties cannot co-exist in a design.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
---
 .../devicetree/bindings/serial/st,stm32-uart.yaml  | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

On Mon, 20 Apr 2020 22:32:03 +0530, mani@kernel.org wrote:
> From: Manivannan Sadhasivam <mani@kernel.org>
> 
> Document the use of CTS/RTS gpios for flow control in STM32 UART
> controller. These properties can be used instead of 'st,hw-flow-ctrl'
> for making use of any gpio pins for flow control instead of dedicated
> pins. It should be noted that both CTS/RTS and 'st,hw-flow-ctrl'
> properties cannot co-exist in a design.
> 
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
> ---
>  .../devicetree/bindings/serial/st,stm32-uart.yaml  | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Hi Mani,

On Mon, Apr 20, 2020 at 7:02 PM <mani@kernel.org> wrote:
> From: Manivannan Sadhasivam <mani@kernel.org>
>
> Document the use of CTS/RTS gpios for flow control in STM32 UART
> controller. These properties can be used instead of 'st,hw-flow-ctrl'
> for making use of any gpio pins for flow control instead of dedicated
> pins. It should be noted that both CTS/RTS and 'st,hw-flow-ctrl'
> properties cannot co-exist in a design.
>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>

> --- a/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml
> +++ b/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml

> @@ -55,6 +61,14 @@ properties:
>    linux,rs485-enabled-at-boot-time: true
>    rs485-rx-during-tx: true
>
> +if:
> +  required:
> +    - st,hw-flow-ctrl

Perhaps "st,hw-flow-ctrl" should be deprecated, in favor of the standard
"uart-has-rtscts" property?
Of course the driver needs to gain support for the latter first.

> +then:
> +  properties:
> +    cts-gpios: false
> +    rts-gpios: false
> +
>  required:
>    - compatible
>    - reg

Gr{oetje,eeting}s,

                        Geert

Hi Geert,


On 5/18/20 9:04 AM, Geert Uytterhoeven wrote:
> Hi Mani,
>
> On Mon, Apr 20, 2020 at 7:02 PM <mani@kernel.org> wrote:
>> From: Manivannan Sadhasivam <mani@kernel.org>
>>
>> Document the use of CTS/RTS gpios for flow control in STM32 UART
>> controller. These properties can be used instead of 'st,hw-flow-ctrl'
>> for making use of any gpio pins for flow control instead of dedicated
>> pins. It should be noted that both CTS/RTS and 'st,hw-flow-ctrl'
>> properties cannot co-exist in a design.
>>
>> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
>> Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
>> --- a/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml
>> +++ b/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml
>> @@ -55,6 +61,14 @@ properties:
>>     linux,rs485-enabled-at-boot-time: true
>>     rs485-rx-during-tx: true
>>
>> +if:
>> +  required:
>> +    - st,hw-flow-ctrl
> Perhaps "st,hw-flow-ctrl" should be deprecated, in favor of the standard
> "uart-has-rtscts" property?
> Of course the driver needs to gain support for the latter first.

You're fully right, the patch to deprecate "st, hw-flow-ctrl" and 
introduce generic "uart-has-rtscts" property in the driver is ready and 
will be sent this week on top of Mani patch.


>
>> +then:
>> +  properties:
>> +    cts-gpios: false
>> +    rts-gpios: false
>> +
>>   required:
>>     - compatible
>>     - reg
> Gr{oetje,eeting}s,
>
>                          Geert
>