[8/8] ARM: dts: STiH407-family: Enable HW flow-control

Message ID 20170124134310.27512-9-lee.jones@linaro.org
State New
Headers show
Series
  • serial: st-asc: Allow handling of RTS line
Related show

Commit Message

Lee Jones Jan. 24, 2017, 1:43 p.m.
Hardware flow-control capability must be specified at a platform
level in order to inform the ASC driver that the platform is capable
(i.e. are the lines wired up, etc).  STiH4{07,10} devices are indeed
capable, so let's provide the property.

Signed-off-by: Lee Jones <lee.jones@linaro.org>

---
 arch/arm/boot/dts/stih407-family.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.10.2

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Comments

Peter Griffin Jan. 25, 2017, 11:40 a.m. | #1
On Wed, 25 Jan 2017, Peter Griffin wrote:

> Hi Lee,

> 

> On Tue, 24 Jan 2017, Lee Jones wrote:

> 

> > Hardware flow-control capability must be specified at a platform

> > level in order to inform the ASC driver that the platform is capable

> > (i.e. are the lines wired up, etc).  STiH4{07,10} devices are indeed

> > capable, so let's provide the property.

> > 

> > Signed-off-by: Lee Jones <lee.jones@linaro.org>

> > ---

> >  arch/arm/boot/dts/stih407-family.dtsi | 2 +-

> >  1 file changed, 1 insertion(+), 1 deletion(-)

> > 

> > diff --git a/arch/arm/boot/dts/stih407-family.dtsi b/arch/arm/boot/dts/stih407-family.dtsi

> > index 9789978..7ada8ea 100644

> > --- a/arch/arm/boot/dts/stih407-family.dtsi

> > +++ b/arch/arm/boot/dts/stih407-family.dtsi

> > @@ -226,7 +226,7 @@

> >  			pinctrl-0 = <&pinctrl_serial0_flowctrl>;

> >  			pinctrl-1 = <&pinctrl_serial0>;

> >  			clocks = <&clk_s_c0_flexgen CLK_EXT2F_A9>;

> > -

> > +			st,hw-flow-control;

> 

> There is a generic serial binding for this already. As this ST property

> hasn't been used upstream, it seems like it would be worth dropping it

> and switching to the generic uart-has-rtscts one.

> 

> See Documentation/devicetree/bindings/serial/serial.txt

> 

>   - uart-has-rtscts: The presence of this property indicates that the

>     UART has dedicated lines for RTS/CTS hardware flow control, and that

>     they are available for use (wired and enabled by pinmux configuration).

>     This depends on both the UART hardware and the board wiring.

>     Note that this property is mutually-exclusive with "cts-gpios" and

>     "rts-gpios" above.


Thinking some more this generic binding definition is a bit restrictive,
particularly the "Note that this property is mutually-exclusive with "cts-gpios"
and "rts-gpios"" part.

As with this series we will have dynamic on-the-fly changing from hw flow
control to gpio control for other configs which the HW IP doesn't support.

IMO the uart-has-rtscts definition should be updated to reflect that they can
be used together in certain circumstances.

regards,

Peter.
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Patch hide | download patch | download mbox

diff --git a/arch/arm/boot/dts/stih407-family.dtsi b/arch/arm/boot/dts/stih407-family.dtsi
index 9789978..7ada8ea 100644
--- a/arch/arm/boot/dts/stih407-family.dtsi
+++ b/arch/arm/boot/dts/stih407-family.dtsi
@@ -226,7 +226,7 @@ 
 			pinctrl-0 = <&pinctrl_serial0_flowctrl>;
 			pinctrl-1 = <&pinctrl_serial0>;
 			clocks = <&clk_s_c0_flexgen CLK_EXT2F_A9>;
-
+			st,hw-flow-control;
 			status = "disabled";
 		};