| Message ID | 1441236479-4941-2-git-send-email-amstan@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Alex, On Wed, Sep 2, 2015 at 4:27 PM, Alexandru M Stan <amstan@chromium.org> wrote: > The flow control lines from a user accessible UART are optional, > the user might not have anything connected to those pins. > In order to prevent random interrupts happening and noise affecting > the cts pin should be pulled up. > > Note that the default state for that pin on the rk3288 is pulled up, > so this patch merely restores them. > > This is similar to what we're already doing with the RX pin, > so it should be safe. At worst it might be a slightly higher power usage > (through ~50 kohms) when the cts is low. > > Suggested-by: Neil Hendin <nhendin@chromium.org> > Signed-off-by: Alexandru M Stan <amstan@chromium.org> > --- > Changes in v2: None Probably not entirely true. ;) > arch/arm/boot/dts/rk3288.dtsi | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) Looks good to me. Reviewed-by: Douglas Anderson <dianders@chromium.org>
diff --git a/arch/arm/boot/dts/rk3288.dtsi b/arch/arm/boot/dts/rk3288.dtsi index 906e938..0e8fd53 100644 --- a/arch/arm/boot/dts/rk3288.dtsi +++ b/arch/arm/boot/dts/rk3288.dtsi @@ -1211,7 +1211,7 @@ }; uart0_cts: uart0-cts { - rockchip,pins = <4 18 RK_FUNC_1 &pcfg_pull_none>; + rockchip,pins = <4 18 RK_FUNC_1 &pcfg_pull_up>; }; uart0_rts: uart0-rts { @@ -1226,7 +1226,7 @@ }; uart1_cts: uart1-cts { - rockchip,pins = <5 10 RK_FUNC_1 &pcfg_pull_none>; + rockchip,pins = <5 10 RK_FUNC_1 &pcfg_pull_up>; }; uart1_rts: uart1-rts { @@ -1249,7 +1249,7 @@ }; uart3_cts: uart3-cts { - rockchip,pins = <7 9 RK_FUNC_1 &pcfg_pull_none>; + rockchip,pins = <7 9 RK_FUNC_1 &pcfg_pull_up>; }; uart3_rts: uart3-rts { @@ -1264,7 +1264,7 @@ }; uart4_cts: uart4-cts { - rockchip,pins = <5 14 3 &pcfg_pull_none>; + rockchip,pins = <5 14 3 &pcfg_pull_up>; }; uart4_rts: uart4-rts {
The flow control lines from a user accessible UART are optional, the user might not have anything connected to those pins. In order to prevent random interrupts happening and noise affecting the cts pin should be pulled up. Note that the default state for that pin on the rk3288 is pulled up, so this patch merely restores them. This is similar to what we're already doing with the RX pin, so it should be safe. At worst it might be a slightly higher power usage (through ~50 kohms) when the cts is low. Suggested-by: Neil Hendin <nhendin@chromium.org> Signed-off-by: Alexandru M Stan <amstan@chromium.org> --- Changes in v2: None arch/arm/boot/dts/rk3288.dtsi | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)