* [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
@ 2019-03-03 12:27 Katsuhiro Suzuki
2019-03-03 13:19 ` Heiko Stuebner
0 siblings, 1 reply; 12+ messages in thread
From: Katsuhiro Suzuki @ 2019-03-03 12:27 UTC (permalink / raw)
To: Heiko Stuebner, linux-rockchip
Cc: linux-arm-kernel, linux-kernel, Katsuhiro Suzuki
This patch increases drive strength of UART2 from 3mA to 12mA for
getting more faster rising edge.
RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
this setting, a bit width of UART is about 667ns.
In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
converter), falling time of RockPro64 UART2 is 40ns, but riging time
is over 650ns. So UART receiver will get wrong data, because receiver
read intermediate data of rising edge.
Rising time becomes 300ns from 650ns if apply this patch. This is not
perfect solution but better than now.
Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
---
arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
index beaa92744a64..e3c8f91ead50 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
@@ -2000,6 +2000,11 @@
drive-strength = <8>;
};
+ pcfg_pull_up_12ma: pcfg-pull-up-12ma {
+ bias-pull-up;
+ drive-strength = <12>;
+ };
+
pcfg_pull_up_18ma: pcfg-pull-up-18ma {
bias-pull-up;
drive-strength = <18>;
@@ -2521,8 +2526,8 @@
uart2c {
uart2c_xfer: uart2c-xfer {
rockchip,pins =
- <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
- <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
+ <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
+ <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
};
};
--
2.20.1
^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-03 12:27 [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2 Katsuhiro Suzuki
@ 2019-03-03 13:19 ` Heiko Stuebner
2019-03-03 14:03 ` Katsuhiro Suzuki
0 siblings, 1 reply; 12+ messages in thread
From: Heiko Stuebner @ 2019-03-03 13:19 UTC (permalink / raw)
To: Katsuhiro Suzuki; +Cc: linux-rockchip, linux-arm-kernel, linux-kernel
Hi,
Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
> This patch increases drive strength of UART2 from 3mA to 12mA for
> getting more faster rising edge.
>
> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
> this setting, a bit width of UART is about 667ns.
>
> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
> converter), falling time of RockPro64 UART2 is 40ns, but riging time
> is over 650ns. So UART receiver will get wrong data, because receiver
> read intermediate data of rising edge.
>
> Rising time becomes 300ns from 650ns if apply this patch. This is not
> perfect solution but better than now.
>
> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
> ---
> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
your changing a core rk3399 property here, so I'd really like to get
input from other board stakeholders on this before applying a core
change.
Could you either include the submitters of other rk3399-boards in the
recipient list so that they're aware or limit the change to rockpro64 for
the time being (aka overriding the property in the board-dts) please?
Thanks
Heiko
> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> index beaa92744a64..e3c8f91ead50 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> @@ -2000,6 +2000,11 @@
> drive-strength = <8>;
> };
>
> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
> + bias-pull-up;
> + drive-strength = <12>;
> + };
> +
> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
> bias-pull-up;
> drive-strength = <18>;
> @@ -2521,8 +2526,8 @@
> uart2c {
> uart2c_xfer: uart2c-xfer {
> rockchip,pins =
> - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
> - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
> + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
> + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
> };
> };
>
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-03 13:19 ` Heiko Stuebner
@ 2019-03-03 14:03 ` Katsuhiro Suzuki
2019-03-03 15:13 ` Tony McKahan
0 siblings, 1 reply; 12+ messages in thread
From: Katsuhiro Suzuki @ 2019-03-03 14:03 UTC (permalink / raw)
To: Heiko Stuebner, Akash Gajjar, Brian Norris, Christoph Muellner,
Dmitry Torokhov, Douglas Anderson, Enric Balletbo i Serra,
Ezequiel Garcia, Jakob Unterwurzacher, Klaus Goger, Levin Du,
Linus Walleij, Manivannan Sadhasivam, Matthias Brugger,
Oskari Lemmela, Robin Murphy, Shawn Lin, Shohei Maruyama,
Tomeu Vizoso, Vicente Bergas, Viresh Kumar
Cc: linux-rockchip, linux-arm-kernel, linux-kernel
Hello Heiko,
Thank you for comments.
On 2019/03/03 22:19, Heiko Stuebner wrote:
> Hi,
>
> Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
>> This patch increases drive strength of UART2 from 3mA to 12mA for
>> getting more faster rising edge.
>>
>> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
>> this setting, a bit width of UART is about 667ns.
>>
>> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
>> converter), falling time of RockPro64 UART2 is 40ns, but riging time
>> is over 650ns. So UART receiver will get wrong data, because receiver
>> read intermediate data of rising edge.
>>
>> Rising time becomes 300ns from 650ns if apply this patch. This is not
>> perfect solution but better than now.
>>
>> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
>> ---
>> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> your changing a core rk3399 property here, so I'd really like to get
> input from other board stakeholders on this before applying a core
> change.
>
> Could you either include the submitters of other rk3399-boards in the
> recipient list so that they're aware or limit the change to rockpro64 for
> the time being (aka overriding the property in the board-dts) please?
>
OK, I'm adding other boards members.
by ./scripts/get_maintainer.pl arch/arm64/boot/dts/rockchip/rk3399-*.dts
RockPro64 directly connect UART2 pins of RK3399 to external connector.
I think maybe other RK3399 boards are facing same problem, but I cannot
check it because I have RockPro64 only...
I'm happy if someone tell me other boards situation.
Best Regards,
Katsuhiro Suzuki
> Thanks
> Heiko
>
>
>
>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>> index beaa92744a64..e3c8f91ead50 100644
>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>> @@ -2000,6 +2000,11 @@
>> drive-strength = <8>;
>> };
>>
>> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
>> + bias-pull-up;
>> + drive-strength = <12>;
>> + };
>> +
>> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
>> bias-pull-up;
>> drive-strength = <18>;
>> @@ -2521,8 +2526,8 @@
>> uart2c {
>> uart2c_xfer: uart2c-xfer {
>> rockchip,pins =
>> - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
>> - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
>> + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
>> + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
>> };
>> };
>>
>>
>
>
>
>
>
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-03 14:03 ` Katsuhiro Suzuki
@ 2019-03-03 15:13 ` Tony McKahan
2019-03-03 17:31 ` Katsuhiro Suzuki
0 siblings, 1 reply; 12+ messages in thread
From: Tony McKahan @ 2019-03-03 15:13 UTC (permalink / raw)
To: Katsuhiro Suzuki
Cc: Heiko Stuebner, Akash Gajjar, Brian Norris, Christoph Muellner,
Dmitry Torokhov, Douglas Anderson, Enric Balletbo i Serra,
Ezequiel Garcia, Jakob Unterwurzacher, Klaus Goger, Levin Du,
Linus Walleij, Manivannan Sadhasivam, Matthias Brugger,
Oskari Lemmela, Robin Murphy, Shawn Lin, Shohei Maruyama,
Tomeu Vizoso, Vicente Bergas, Viresh Kumar, linux-rockchip,
linux-kernel, linux-arm-kernel
On Sun, Mar 3, 2019 at 9:04 AM Katsuhiro Suzuki <katsuhiro@katsuster.net> wrote:
>
> Hello Heiko,
>
> Thank you for comments.
>
> On 2019/03/03 22:19, Heiko Stuebner wrote:
> > Hi,
> >
> > Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
> >> This patch increases drive strength of UART2 from 3mA to 12mA for
> >> getting more faster rising edge.
> >>
> >> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
> >> this setting, a bit width of UART is about 667ns.
> >>
> >> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
> >> converter), falling time of RockPro64 UART2 is 40ns, but riging time
> >> is over 650ns. So UART receiver will get wrong data, because receiver
> >> read intermediate data of rising edge.
> >>
> >> Rising time becomes 300ns from 650ns if apply this patch. This is not
> >> perfect solution but better than now.
> >>
> >> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
> >> ---
> >> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
> >> 1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > your changing a core rk3399 property here, so I'd really like to get
> > input from other board stakeholders on this before applying a core
> > change.
> >
> > Could you either include the submitters of other rk3399-boards in the
> > recipient list so that they're aware or limit the change to rockpro64 for
> > the time being (aka overriding the property in the board-dts) please?
> >
>
> OK, I'm adding other boards members.
> by ./scripts/get_maintainer.pl arch/arm64/boot/dts/rockchip/rk3399-*.dts
>
>
> RockPro64 directly connect UART2 pins of RK3399 to external connector.
> I think maybe other RK3399 boards are facing same problem, but I cannot
> check it because I have RockPro64 only...
>
> I'm happy if someone tell me other boards situation.
I'm pulling out other rockchip boards momentarily to see what kind of
population we have.
Note these are not all running 5.x kernels, however none of them have
the UART2 drive levels modified to my knowledge, and regardless, none
show over 100 ns.
board: rise/fall
rk3399-roc-pc: 90ns/90ns
rk3399-rockpro64 V2.0: 90ns/45ns
rk3399-rockpro64 V2.1: 40ns/41ns
Please make sure there's not a large amount of flux or something
around the terminals on your board, that seems excessively high.
>
> Best Regards,
> Katsuhiro Suzuki
>
>
> > Thanks
> > Heiko
> >
> >
> >
> >> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> >> index beaa92744a64..e3c8f91ead50 100644
> >> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> >> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> >> @@ -2000,6 +2000,11 @@
> >> drive-strength = <8>;
> >> };
> >>
> >> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
> >> + bias-pull-up;
> >> + drive-strength = <12>;
> >> + };
> >> +
> >> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
> >> bias-pull-up;
> >> drive-strength = <18>;
> >> @@ -2521,8 +2526,8 @@
> >> uart2c {
> >> uart2c_xfer: uart2c-xfer {
> >> rockchip,pins =
> >> - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
> >> - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
> >> + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
> >> + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
> >> };
> >> };
> >>
> >>
> >
> >
> >
> >
> >
> >
>
>
> _______________________________________________
> Linux-rockchip mailing list
> Linux-rockchip@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rockchip
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-03 15:13 ` Tony McKahan
@ 2019-03-03 17:31 ` Katsuhiro Suzuki
2019-03-03 18:45 ` Tony McKahan
0 siblings, 1 reply; 12+ messages in thread
From: Katsuhiro Suzuki @ 2019-03-03 17:31 UTC (permalink / raw)
To: Tony McKahan
Cc: Heiko Stuebner, Akash Gajjar, Brian Norris, Christoph Muellner,
Dmitry Torokhov, Douglas Anderson, Enric Balletbo i Serra,
Ezequiel Garcia, Jakob Unterwurzacher, Klaus Goger, Levin Du,
Linus Walleij, Manivannan Sadhasivam, Matthias Brugger,
Oskari Lemmela, Robin Murphy, Shawn Lin, Shohei Maruyama,
Tomeu Vizoso, Vicente Bergas, Viresh Kumar, linux-rockchip,
linux-kernel, linux-arm-kernel
Hello Tony,
On 2019/03/04 0:13, Tony McKahan wrote:
> On Sun, Mar 3, 2019 at 9:04 AM Katsuhiro Suzuki <katsuhiro@katsuster.net> wrote:
>>
>> Hello Heiko,
>>
>> Thank you for comments.
>>
>> On 2019/03/03 22:19, Heiko Stuebner wrote:
>>> Hi,
>>>
>>> Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
>>>> This patch increases drive strength of UART2 from 3mA to 12mA for
>>>> getting more faster rising edge.
>>>>
>>>> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
>>>> this setting, a bit width of UART is about 667ns.
>>>>
>>>> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
>>>> converter), falling time of RockPro64 UART2 is 40ns, but riging time
>>>> is over 650ns. So UART receiver will get wrong data, because receiver
>>>> read intermediate data of rising edge.
>>>>
>>>> Rising time becomes 300ns from 650ns if apply this patch. This is not
>>>> perfect solution but better than now.
>>>>
>>>> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
>>>> ---
>>>> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
>>>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>>
>>> your changing a core rk3399 property here, so I'd really like to get
>>> input from other board stakeholders on this before applying a core
>>> change.
>>>
>>> Could you either include the submitters of other rk3399-boards in the
>>> recipient list so that they're aware or limit the change to rockpro64 for
>>> the time being (aka overriding the property in the board-dts) please?
>>>
>>
>> OK, I'm adding other boards members.
>> by ./scripts/get_maintainer.pl arch/arm64/boot/dts/rockchip/rk3399-*.dts
>>
>>
>> RockPro64 directly connect UART2 pins of RK3399 to external connector.
>> I think maybe other RK3399 boards are facing same problem, but I cannot
>> check it because I have RockPro64 only...
>>
>> I'm happy if someone tell me other boards situation.
>
> I'm pulling out other rockchip boards momentarily to see what kind of
> population we have.
>
> Note these are not all running 5.x kernels, however none of them have
> the UART2 drive levels modified to my knowledge, and regardless, none
> show over 100 ns.
>
> board: rise/fall
>
> rk3399-roc-pc: 90ns/90ns
> rk3399-rockpro64 V2.0: 90ns/45ns
> rk3399-rockpro64 V2.1: 40ns/41ns
>
> Please make sure there's not a large amount of flux or something
> around the terminals on your board, that seems excessively high.
>
Thank you for valuable information. For more deeply discussion,
I tried other conditions and watch the rise/fall times.
1) Not connect
The rise/fall times are 40ns/5ns when nothing connect (impedance is
very high) to external pin of RockPro64.
What UART device are you using with RockPro64? If you use some device
with RockPro64 and board shows rise/fall times = 90ns/45ns, my device
is not suitable for RockPro64 by some reason. So it's better to drop
my patch.
2) Other SoC
I have other SoC board rk3328-rock64, Rock64 shows rise/fall times =
90ns/80ns when same UART-USB device is connected to UART pin.
I think it shows rk3399's (or RockPro64's?) drive strength is a little
weak. So it's better to increase the drive strength of UART of rk3399.
Best Regards,
Katsuhiro Suzuki
>>
>> Best Regards,
>> Katsuhiro Suzuki
>>
>>
>>> Thanks
>>> Heiko
>>>
>>>
>>>
>>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>> index beaa92744a64..e3c8f91ead50 100644
>>>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>> @@ -2000,6 +2000,11 @@
>>>> drive-strength = <8>;
>>>> };
>>>>
>>>> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
>>>> + bias-pull-up;
>>>> + drive-strength = <12>;
>>>> + };
>>>> +
>>>> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
>>>> bias-pull-up;
>>>> drive-strength = <18>;
>>>> @@ -2521,8 +2526,8 @@
>>>> uart2c {
>>>> uart2c_xfer: uart2c-xfer {
>>>> rockchip,pins =
>>>> - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
>>>> - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
>>>> + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
>>>> + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
>>>> };
>>>> };
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>> _______________________________________________
>> Linux-rockchip mailing list
>> Linux-rockchip@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-rockchip
>
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-03 17:31 ` Katsuhiro Suzuki
@ 2019-03-03 18:45 ` Tony McKahan
2019-03-03 19:12 ` Tony McKahan
2019-03-03 19:50 ` Robin Murphy
0 siblings, 2 replies; 12+ messages in thread
From: Tony McKahan @ 2019-03-03 18:45 UTC (permalink / raw)
To: Katsuhiro Suzuki
Cc: Heiko Stuebner, Akash Gajjar, Brian Norris, Christoph Muellner,
Dmitry Torokhov, Douglas Anderson, Enric Balletbo i Serra,
Ezequiel Garcia, Jakob Unterwurzacher, Klaus Goger, Levin Du,
Linus Walleij, Manivannan Sadhasivam, Matthias Brugger,
Oskari Lemmela, Robin Murphy, Shawn Lin, Shohei Maruyama,
Tomeu Vizoso, Vicente Bergas, Viresh Kumar, linux-rockchip,
linux-kernel, linux-arm-kernel
Hello Katsushiro,
On Sun, Mar 3, 2019 at 12:31 PM Katsuhiro Suzuki
<katsuhiro@katsuster.net> wrote:
>
> Hello Tony,
>
> On 2019/03/04 0:13, Tony McKahan wrote:
> > On Sun, Mar 3, 2019 at 9:04 AM Katsuhiro Suzuki <katsuhiro@katsuster.net> wrote:
> >>
> >> Hello Heiko,
> >>
> >> Thank you for comments.
> >>
> >> On 2019/03/03 22:19, Heiko Stuebner wrote:
> >>> Hi,
> >>>
> >>> Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
> >>>> This patch increases drive strength of UART2 from 3mA to 12mA for
> >>>> getting more faster rising edge.
> >>>>
> >>>> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
> >>>> this setting, a bit width of UART is about 667ns.
> >>>>
> >>>> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
> >>>> converter), falling time of RockPro64 UART2 is 40ns, but riging time
> >>>> is over 650ns. So UART receiver will get wrong data, because receiver
> >>>> read intermediate data of rising edge.
> >>>>
> >>>> Rising time becomes 300ns from 650ns if apply this patch. This is not
> >>>> perfect solution but better than now.
> >>>>
> >>>> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
> >>>> ---
> >>>> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
> >>>> 1 file changed, 7 insertions(+), 2 deletions(-)
> >>>
> >>> your changing a core rk3399 property here, so I'd really like to get
> >>> input from other board stakeholders on this before applying a core
> >>> change.
> >>>
> >>> Could you either include the submitters of other rk3399-boards in the
> >>> recipient list so that they're aware or limit the change to rockpro64 for
> >>> the time being (aka overriding the property in the board-dts) please?
> >>>
> >>
> >> OK, I'm adding other boards members.
> >> by ./scripts/get_maintainer.pl arch/arm64/boot/dts/rockchip/rk3399-*.dts
> >>
> >>
> >> RockPro64 directly connect UART2 pins of RK3399 to external connector.
> >> I think maybe other RK3399 boards are facing same problem, but I cannot
> >> check it because I have RockPro64 only...
> >>
> >> I'm happy if someone tell me other boards situation.
> >
> > I'm pulling out other rockchip boards momentarily to see what kind of
> > population we have.
> >
> > Note these are not all running 5.x kernels, however none of them have
> > the UART2 drive levels modified to my knowledge, and regardless, none
> > show over 100 ns.
> >
> > board: rise/fall
> >
> > rk3399-roc-pc: 90ns/90ns
> > rk3399-rockpro64 V2.0: 90ns/45ns
> > rk3399-rockpro64 V2.1: 40ns/41ns
> >
> > Please make sure there's not a large amount of flux or something
> > around the terminals on your board, that seems excessively high.
> >
>
> Thank you for valuable information. For more deeply discussion,
> I tried other conditions and watch the rise/fall times.
>
> 1) Not connect
> The rise/fall times are 40ns/5ns when nothing connect (impedance is
> very high) to external pin of RockPro64.
>
> What UART device are you using with RockPro64? If you use some device
> with RockPro64 and board shows rise/fall times = 90ns/45ns, my device
> is not suitable for RockPro64 by some reason. So it's better to drop
> my patch.
The adapter is an FTDI FT232RL breakout board, attached with some
generic Dupont connector jumpers.
Interesting your RockPro is showing this symptom, perhaps there is a
cold solder joint somewhere introducing resistance?
>
> 2) Other SoC
> I have other SoC board rk3328-rock64, Rock64 shows rise/fall times =
> 90ns/80ns when same UART-USB device is connected to UART pin.
I measured similar on my Rock64 as well.
>
> I think it shows rk3399's (or RockPro64's?) drive strength is a little
> weak. So it's better to increase the drive strength of UART of rk3399.
I do not think this is a bad idea generally, it simply allows for more
available current from the interface. I'll let others be the judge of
that, however.
>
> Best Regards,
> Katsuhiro Suzuki
>
> >>
> >> Best Regards,
> >> Katsuhiro Suzuki
> >>
> >>
> >>> Thanks
> >>> Heiko
> >>>
> >>>
> >>>
> >>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> >>>> index beaa92744a64..e3c8f91ead50 100644
> >>>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> >>>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> >>>> @@ -2000,6 +2000,11 @@
> >>>> drive-strength = <8>;
> >>>> };
> >>>>
> >>>> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
> >>>> + bias-pull-up;
> >>>> + drive-strength = <12>;
> >>>> + };
> >>>> +
> >>>> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
> >>>> bias-pull-up;
> >>>> drive-strength = <18>;
> >>>> @@ -2521,8 +2526,8 @@
> >>>> uart2c {
> >>>> uart2c_xfer: uart2c-xfer {
> >>>> rockchip,pins =
> >>>> - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
> >>>> - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
> >>>> + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
> >>>> + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
> >>>> };
> >>>> };
> >>>>
> >>>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>
> >>
> >> _______________________________________________
> >> Linux-rockchip mailing list
> >> Linux-rockchip@lists.infradead.org
> >> http://lists.infradead.org/mailman/listinfo/linux-rockchip
> >
> >
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-03 18:45 ` Tony McKahan
@ 2019-03-03 19:12 ` Tony McKahan
2019-03-04 13:56 ` Katsuhiro Suzuki
2019-03-03 19:50 ` Robin Murphy
1 sibling, 1 reply; 12+ messages in thread
From: Tony McKahan @ 2019-03-03 19:12 UTC (permalink / raw)
To: Katsuhiro Suzuki
Cc: Heiko Stuebner, Akash Gajjar, Brian Norris, Christoph Muellner,
Dmitry Torokhov, Douglas Anderson, Enric Balletbo i Serra,
Ezequiel Garcia, Jakob Unterwurzacher, Klaus Goger, Levin Du,
Linus Walleij, Manivannan Sadhasivam, Matthias Brugger,
Oskari Lemmela, Robin Murphy, Shawn Lin, Shohei Maruyama,
Tomeu Vizoso, Vicente Bergas, Viresh Kumar, linux-rockchip,
linux-kernel, linux-arm-kernel
On Sun, Mar 3, 2019 at 1:45 PM Tony McKahan <tonymckahan@gmail.com> wrote:
>
> Hello Katsushiro,
And apologies for the extra "s", typing too quickly I'm afraid.
>
> On Sun, Mar 3, 2019 at 12:31 PM Katsuhiro Suzuki
> <katsuhiro@katsuster.net> wrote:
> >
> > Hello Tony,
> >
> > On 2019/03/04 0:13, Tony McKahan wrote:
> > > On Sun, Mar 3, 2019 at 9:04 AM Katsuhiro Suzuki <katsuhiro@katsuster.net> wrote:
> > >>
> > >> Hello Heiko,
> > >>
> > >> Thank you for comments.
> > >>
> > >> On 2019/03/03 22:19, Heiko Stuebner wrote:
> > >>> Hi,
> > >>>
> > >>> Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
> > >>>> This patch increases drive strength of UART2 from 3mA to 12mA for
> > >>>> getting more faster rising edge.
> > >>>>
> > >>>> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
> > >>>> this setting, a bit width of UART is about 667ns.
> > >>>>
> > >>>> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
> > >>>> converter), falling time of RockPro64 UART2 is 40ns, but riging time
> > >>>> is over 650ns. So UART receiver will get wrong data, because receiver
> > >>>> read intermediate data of rising edge.
> > >>>>
> > >>>> Rising time becomes 300ns from 650ns if apply this patch. This is not
> > >>>> perfect solution but better than now.
> > >>>>
> > >>>> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
> > >>>> ---
> > >>>> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
> > >>>> 1 file changed, 7 insertions(+), 2 deletions(-)
> > >>>
> > >>> your changing a core rk3399 property here, so I'd really like to get
> > >>> input from other board stakeholders on this before applying a core
> > >>> change.
> > >>>
> > >>> Could you either include the submitters of other rk3399-boards in the
> > >>> recipient list so that they're aware or limit the change to rockpro64 for
> > >>> the time being (aka overriding the property in the board-dts) please?
> > >>>
> > >>
> > >> OK, I'm adding other boards members.
> > >> by ./scripts/get_maintainer.pl arch/arm64/boot/dts/rockchip/rk3399-*.dts
> > >>
> > >>
> > >> RockPro64 directly connect UART2 pins of RK3399 to external connector.
> > >> I think maybe other RK3399 boards are facing same problem, but I cannot
> > >> check it because I have RockPro64 only...
> > >>
> > >> I'm happy if someone tell me other boards situation.
> > >
> > > I'm pulling out other rockchip boards momentarily to see what kind of
> > > population we have.
> > >
> > > Note these are not all running 5.x kernels, however none of them have
> > > the UART2 drive levels modified to my knowledge, and regardless, none
> > > show over 100 ns.
> > >
> > > board: rise/fall
> > >
> > > rk3399-roc-pc: 90ns/90ns
> > > rk3399-rockpro64 V2.0: 90ns/45ns
> > > rk3399-rockpro64 V2.1: 40ns/41ns
> > >
> > > Please make sure there's not a large amount of flux or something
> > > around the terminals on your board, that seems excessively high.
> > >
> >
> > Thank you for valuable information. For more deeply discussion,
> > I tried other conditions and watch the rise/fall times.
> >
> > 1) Not connect
> > The rise/fall times are 40ns/5ns when nothing connect (impedance is
> > very high) to external pin of RockPro64.
> >
> > What UART device are you using with RockPro64? If you use some device
> > with RockPro64 and board shows rise/fall times = 90ns/45ns, my device
> > is not suitable for RockPro64 by some reason. So it's better to drop
> > my patch.
>
> The adapter is an FTDI FT232RL breakout board, attached with some
> generic Dupont connector jumpers.
> Interesting your RockPro is showing this symptom, perhaps there is a
> cold solder joint somewhere introducing resistance?
>
> >
> > 2) Other SoC
> > I have other SoC board rk3328-rock64, Rock64 shows rise/fall times =
> > 90ns/80ns when same UART-USB device is connected to UART pin.
>
> I measured similar on my Rock64 as well.
>
> >
> > I think it shows rk3399's (or RockPro64's?) drive strength is a little
> > weak. So it's better to increase the drive strength of UART of rk3399.
>
> I do not think this is a bad idea generally, it simply allows for more
> available current from the interface. I'll let others be the judge of
> that, however.
>
> >
> > Best Regards,
> > Katsuhiro Suzuki
> >
> > >>
> > >> Best Regards,
> > >> Katsuhiro Suzuki
> > >>
> > >>
> > >>> Thanks
> > >>> Heiko
> > >>>
> > >>>
> > >>>
> > >>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > >>>> index beaa92744a64..e3c8f91ead50 100644
> > >>>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > >>>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> > >>>> @@ -2000,6 +2000,11 @@
> > >>>> drive-strength = <8>;
> > >>>> };
> > >>>>
> > >>>> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
> > >>>> + bias-pull-up;
> > >>>> + drive-strength = <12>;
> > >>>> + };
> > >>>> +
> > >>>> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
> > >>>> bias-pull-up;
> > >>>> drive-strength = <18>;
> > >>>> @@ -2521,8 +2526,8 @@
> > >>>> uart2c {
> > >>>> uart2c_xfer: uart2c-xfer {
> > >>>> rockchip,pins =
> > >>>> - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
> > >>>> - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
> > >>>> + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
> > >>>> + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
> > >>>> };
> > >>>> };
> > >>>>
> > >>>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>
> > >>
> > >> _______________________________________________
> > >> Linux-rockchip mailing list
> > >> Linux-rockchip@lists.infradead.org
> > >> http://lists.infradead.org/mailman/listinfo/linux-rockchip
> > >
> > >
> >
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-03 18:45 ` Tony McKahan
2019-03-03 19:12 ` Tony McKahan
@ 2019-03-03 19:50 ` Robin Murphy
2019-03-03 20:41 ` Tony McKahan
1 sibling, 1 reply; 12+ messages in thread
From: Robin Murphy @ 2019-03-03 19:50 UTC (permalink / raw)
To: Tony McKahan, Katsuhiro Suzuki
Cc: Heiko Stuebner, Akash Gajjar, Brian Norris, Christoph Muellner,
Dmitry Torokhov, Douglas Anderson, Enric Balletbo i Serra,
Ezequiel Garcia, Jakob Unterwurzacher, Klaus Goger, Levin Du,
Linus Walleij, Manivannan Sadhasivam, Matthias Brugger,
Oskari Lemmela, Shawn Lin, Shohei Maruyama, Tomeu Vizoso,
Vicente Bergas, Viresh Kumar, linux-rockchip, linux-kernel,
linux-arm-kernel
On 2019-03-03 6:45 pm, Tony McKahan wrote:
> Hello Katsushiro,
>
> On Sun, Mar 3, 2019 at 12:31 PM Katsuhiro Suzuki
> <katsuhiro@katsuster.net> wrote:
>>
>> Hello Tony,
>>
>> On 2019/03/04 0:13, Tony McKahan wrote:
>>> On Sun, Mar 3, 2019 at 9:04 AM Katsuhiro Suzuki <katsuhiro@katsuster.net> wrote:
>>>>
>>>> Hello Heiko,
>>>>
>>>> Thank you for comments.
>>>>
>>>> On 2019/03/03 22:19, Heiko Stuebner wrote:
>>>>> Hi,
>>>>>
>>>>> Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
>>>>>> This patch increases drive strength of UART2 from 3mA to 12mA for
>>>>>> getting more faster rising edge.
>>>>>>
>>>>>> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
>>>>>> this setting, a bit width of UART is about 667ns.
>>>>>>
>>>>>> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
>>>>>> converter), falling time of RockPro64 UART2 is 40ns, but riging time
>>>>>> is over 650ns. So UART receiver will get wrong data, because receiver
>>>>>> read intermediate data of rising edge.
>>>>>>
>>>>>> Rising time becomes 300ns from 650ns if apply this patch. This is not
>>>>>> perfect solution but better than now.
>>>>>>
>>>>>> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
>>>>>> ---
>>>>>> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
>>>>>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>>>>
>>>>> your changing a core rk3399 property here, so I'd really like to get
>>>>> input from other board stakeholders on this before applying a core
>>>>> change.
>>>>>
>>>>> Could you either include the submitters of other rk3399-boards in the
>>>>> recipient list so that they're aware or limit the change to rockpro64 for
>>>>> the time being (aka overriding the property in the board-dts) please?
>>>>>
>>>>
>>>> OK, I'm adding other boards members.
>>>> by ./scripts/get_maintainer.pl arch/arm64/boot/dts/rockchip/rk3399-*.dts
>>>>
>>>>
>>>> RockPro64 directly connect UART2 pins of RK3399 to external connector.
>>>> I think maybe other RK3399 boards are facing same problem, but I cannot
>>>> check it because I have RockPro64 only...
>>>>
>>>> I'm happy if someone tell me other boards situation.
>>>
>>> I'm pulling out other rockchip boards momentarily to see what kind of
>>> population we have.
>>>
>>> Note these are not all running 5.x kernels, however none of them have
>>> the UART2 drive levels modified to my knowledge, and regardless, none
>>> show over 100 ns.
>>>
>>> board: rise/fall
>>>
>>> rk3399-roc-pc: 90ns/90ns
>>> rk3399-rockpro64 V2.0: 90ns/45ns
>>> rk3399-rockpro64 V2.1: 40ns/41ns
I'm having to eyeball off a 20MHz analog scope (thank goodness for "yes"
being able to generate a nice periodic signal), but for my NanoPC-T4
with a cheap eBay FT232R adapter both rise and fall times are certainly
<100ns. FWIW I've not noticed any issues with letting the Bluetooth
interface on UART0 run flat-out at 4Mbaud either.
>>>
>>> Please make sure there's not a large amount of flux or something
>>> around the terminals on your board, that seems excessively high.
>>>
>>
>> Thank you for valuable information. For more deeply discussion,
>> I tried other conditions and watch the rise/fall times.
>>
>> 1) Not connect
>> The rise/fall times are 40ns/5ns when nothing connect (impedance is
>> very high) to external pin of RockPro64.
>>
>> What UART device are you using with RockPro64? If you use some device
>> with RockPro64 and board shows rise/fall times = 90ns/45ns, my device
>> is not suitable for RockPro64 by some reason. So it's better to drop
>> my patch.
>
> The adapter is an FTDI FT232RL breakout board, attached with some
> generic Dupont connector jumpers.
> Interesting your RockPro is showing this symptom, perhaps there is a
> cold solder joint somewhere introducing resistance?
>
>>
>> 2) Other SoC
>> I have other SoC board rk3328-rock64, Rock64 shows rise/fall times =
>> 90ns/80ns when same UART-USB device is connected to UART pin.
>
> I measured similar on my Rock64 as well.
>
>>
>> I think it shows rk3399's (or RockPro64's?) drive strength is a little
>> weak. So it's better to increase the drive strength of UART of rk3399.
>
> I do not think this is a bad idea generally, it simply allows for more
> available current from the interface. I'll let others be the judge of
> that, however.
There may be RK3399 users who would care about the possible EMI impact,
so it's probably still best to limit such a change to boards which
definitely need it.
Robin.
>
>>
>> Best Regards,
>> Katsuhiro Suzuki
>>
>>>>
>>>> Best Regards,
>>>> Katsuhiro Suzuki
>>>>
>>>>
>>>>> Thanks
>>>>> Heiko
>>>>>
>>>>>
>>>>>
>>>>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>> index beaa92744a64..e3c8f91ead50 100644
>>>>>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>> @@ -2000,6 +2000,11 @@
>>>>>> drive-strength = <8>;
>>>>>> };
>>>>>>
>>>>>> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
>>>>>> + bias-pull-up;
>>>>>> + drive-strength = <12>;
>>>>>> + };
>>>>>> +
>>>>>> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
>>>>>> bias-pull-up;
>>>>>> drive-strength = <18>;
>>>>>> @@ -2521,8 +2526,8 @@
>>>>>> uart2c {
>>>>>> uart2c_xfer: uart2c-xfer {
>>>>>> rockchip,pins =
>>>>>> - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
>>>>>> - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
>>>>>> + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
>>>>>> + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
>>>>>> };
>>>>>> };
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Linux-rockchip mailing list
>>>> Linux-rockchip@lists.infradead.org
>>>> http://lists.infradead.org/mailman/listinfo/linux-rockchip
>>>
>>>
>>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-03 19:50 ` Robin Murphy
@ 2019-03-03 20:41 ` Tony McKahan
2019-03-04 13:59 ` Katsuhiro Suzuki
0 siblings, 1 reply; 12+ messages in thread
From: Tony McKahan @ 2019-03-03 20:41 UTC (permalink / raw)
To: Robin Murphy
Cc: Katsuhiro Suzuki, Heiko Stuebner, Akash Gajjar, Brian Norris,
Christoph Muellner, Dmitry Torokhov, Douglas Anderson,
Enric Balletbo i Serra, Ezequiel Garcia, Jakob Unterwurzacher,
Klaus Goger, Levin Du, Linus Walleij, Manivannan Sadhasivam,
Matthias Brugger, Oskari Lemmela, Shawn Lin, Shohei Maruyama,
Tomeu Vizoso, Vicente Bergas, Viresh Kumar, linux-rockchip,
linux-kernel, linux-arm-kernel
On Sun, Mar 3, 2019 at 2:51 PM Robin Murphy <robin.murphy@arm.com> wrote:
>
> On 2019-03-03 6:45 pm, Tony McKahan wrote:
> > Hello Katsushiro,
> >
> > On Sun, Mar 3, 2019 at 12:31 PM Katsuhiro Suzuki
> > <katsuhiro@katsuster.net> wrote:
> >>
> >> Hello Tony,
> >>
> >> On 2019/03/04 0:13, Tony McKahan wrote:
> >>> On Sun, Mar 3, 2019 at 9:04 AM Katsuhiro Suzuki <katsuhiro@katsuster.net> wrote:
> >>>>
> >>>> Hello Heiko,
> >>>>
> >>>> Thank you for comments.
> >>>>
> >>>> On 2019/03/03 22:19, Heiko Stuebner wrote:
> >>>>> Hi,
> >>>>>
> >>>>> Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
> >>>>>> This patch increases drive strength of UART2 from 3mA to 12mA for
> >>>>>> getting more faster rising edge.
> >>>>>>
> >>>>>> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
> >>>>>> this setting, a bit width of UART is about 667ns.
> >>>>>>
> >>>>>> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
> >>>>>> converter), falling time of RockPro64 UART2 is 40ns, but riging time
> >>>>>> is over 650ns. So UART receiver will get wrong data, because receiver
> >>>>>> read intermediate data of rising edge.
> >>>>>>
> >>>>>> Rising time becomes 300ns from 650ns if apply this patch. This is not
> >>>>>> perfect solution but better than now.
> >>>>>>
> >>>>>> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
> >>>>>> ---
> >>>>>> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
> >>>>>> 1 file changed, 7 insertions(+), 2 deletions(-)
> >>>>>
> >>>>> your changing a core rk3399 property here, so I'd really like to get
> >>>>> input from other board stakeholders on this before applying a core
> >>>>> change.
> >>>>>
> >>>>> Could you either include the submitters of other rk3399-boards in the
> >>>>> recipient list so that they're aware or limit the change to rockpro64 for
> >>>>> the time being (aka overriding the property in the board-dts) please?
> >>>>>
> >>>>
> >>>> OK, I'm adding other boards members.
> >>>> by ./scripts/get_maintainer.pl arch/arm64/boot/dts/rockchip/rk3399-*.dts
> >>>>
> >>>>
> >>>> RockPro64 directly connect UART2 pins of RK3399 to external connector.
> >>>> I think maybe other RK3399 boards are facing same problem, but I cannot
> >>>> check it because I have RockPro64 only...
> >>>>
> >>>> I'm happy if someone tell me other boards situation.
> >>>
> >>> I'm pulling out other rockchip boards momentarily to see what kind of
> >>> population we have.
> >>>
> >>> Note these are not all running 5.x kernels, however none of them have
> >>> the UART2 drive levels modified to my knowledge, and regardless, none
> >>> show over 100 ns.
> >>>
> >>> board: rise/fall
> >>>
> >>> rk3399-roc-pc: 90ns/90ns
> >>> rk3399-rockpro64 V2.0: 90ns/45ns
> >>> rk3399-rockpro64 V2.1: 40ns/41ns
>
> I'm having to eyeball off a 20MHz analog scope (thank goodness for "yes"
> being able to generate a nice periodic signal), but for my NanoPC-T4
> with a cheap eBay FT232R adapter both rise and fall times are certainly
> <100ns. FWIW I've not noticed any issues with letting the Bluetooth
> interface on UART0 run flat-out at 4Mbaud either.
>
> >>>
> >>> Please make sure there's not a large amount of flux or something
> >>> around the terminals on your board, that seems excessively high.
> >>>
> >>
> >> Thank you for valuable information. For more deeply discussion,
> >> I tried other conditions and watch the rise/fall times.
> >>
> >> 1) Not connect
> >> The rise/fall times are 40ns/5ns when nothing connect (impedance is
> >> very high) to external pin of RockPro64.
> >>
> >> What UART device are you using with RockPro64? If you use some device
> >> with RockPro64 and board shows rise/fall times = 90ns/45ns, my device
> >> is not suitable for RockPro64 by some reason. So it's better to drop
> >> my patch.
> >
> > The adapter is an FTDI FT232RL breakout board, attached with some
> > generic Dupont connector jumpers.
> > Interesting your RockPro is showing this symptom, perhaps there is a
> > cold solder joint somewhere introducing resistance?
> >
> >>
> >> 2) Other SoC
> >> I have other SoC board rk3328-rock64, Rock64 shows rise/fall times =
> >> 90ns/80ns when same UART-USB device is connected to UART pin.
> >
> > I measured similar on my Rock64 as well.
> >
> >>
> >> I think it shows rk3399's (or RockPro64's?) drive strength is a little
> >> weak. So it's better to increase the drive strength of UART of rk3399.
> >
> > I do not think this is a bad idea generally, it simply allows for more
> > available current from the interface. I'll let others be the judge of
> > that, however.
>
> There may be RK3399 users who would care about the possible EMI impact,
> so it's probably still best to limit such a change to boards which
> definitely need it.
>
Ah, good point.
As to speeds achievable, I've only run into drive level issues with
SD/SDIO, but that's all the way up at 25-50 MHz.
Tony
> Robin.
>
> >
> >>
> >> Best Regards,
> >> Katsuhiro Suzuki
> >>
> >>>>
> >>>> Best Regards,
> >>>> Katsuhiro Suzuki
> >>>>
> >>>>
> >>>>> Thanks
> >>>>> Heiko
> >>>>>
> >>>>>
> >>>>>
> >>>>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> >>>>>> index beaa92744a64..e3c8f91ead50 100644
> >>>>>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> >>>>>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> >>>>>> @@ -2000,6 +2000,11 @@
> >>>>>> drive-strength = <8>;
> >>>>>> };
> >>>>>>
> >>>>>> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
> >>>>>> + bias-pull-up;
> >>>>>> + drive-strength = <12>;
> >>>>>> + };
> >>>>>> +
> >>>>>> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
> >>>>>> bias-pull-up;
> >>>>>> drive-strength = <18>;
> >>>>>> @@ -2521,8 +2526,8 @@
> >>>>>> uart2c {
> >>>>>> uart2c_xfer: uart2c-xfer {
> >>>>>> rockchip,pins =
> >>>>>> - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
> >>>>>> - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
> >>>>>> + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
> >>>>>> + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
> >>>>>> };
> >>>>>> };
> >>>>>>
> >>>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>> _______________________________________________
> >>>> Linux-rockchip mailing list
> >>>> Linux-rockchip@lists.infradead.org
> >>>> http://lists.infradead.org/mailman/listinfo/linux-rockchip
> >>>
> >>>
> >>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-03 19:12 ` Tony McKahan
@ 2019-03-04 13:56 ` Katsuhiro Suzuki
0 siblings, 0 replies; 12+ messages in thread
From: Katsuhiro Suzuki @ 2019-03-04 13:56 UTC (permalink / raw)
To: Tony McKahan
Cc: Heiko Stuebner, Viresh Kumar, Linus Walleij, linux-kernel,
Klaus Goger, Manivannan Sadhasivam, Brian Norris, linux-rockchip,
Shawn Lin, Akash Gajjar, Vicente Bergas, Levin Du,
Ezequiel Garcia, linux-arm-kernel, Shohei Maruyama,
Matthias Brugger, Tomeu Vizoso, Dmitry Torokhov,
Douglas Anderson, Jakob Unterwurzacher, Oskari Lemmela,
Enric Balletbo i Serra, Robin Murphy, Christoph Muellner
No problem! Thank you for discussion :)
On 2019/03/04 4:12, Tony McKahan wrote:
> On Sun, Mar 3, 2019 at 1:45 PM Tony McKahan <tonymckahan@gmail.com> wrote:
>>
>> Hello Katsushiro,
>
> And apologies for the extra "s", typing too quickly I'm afraid.
>>
>> On Sun, Mar 3, 2019 at 12:31 PM Katsuhiro Suzuki
>> <katsuhiro@katsuster.net> wrote:
>>>
>>> Hello Tony,
>>>
>>> On 2019/03/04 0:13, Tony McKahan wrote:
>>>> On Sun, Mar 3, 2019 at 9:04 AM Katsuhiro Suzuki <katsuhiro@katsuster.net> wrote:
>>>>>
>>>>> Hello Heiko,
>>>>>
>>>>> Thank you for comments.
>>>>>
>>>>> On 2019/03/03 22:19, Heiko Stuebner wrote:
>>>>>> Hi,
>>>>>>
>>>>>> Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
>>>>>>> This patch increases drive strength of UART2 from 3mA to 12mA for
>>>>>>> getting more faster rising edge.
>>>>>>>
>>>>>>> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
>>>>>>> this setting, a bit width of UART is about 667ns.
>>>>>>>
>>>>>>> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
>>>>>>> converter), falling time of RockPro64 UART2 is 40ns, but riging time
>>>>>>> is over 650ns. So UART receiver will get wrong data, because receiver
>>>>>>> read intermediate data of rising edge.
>>>>>>>
>>>>>>> Rising time becomes 300ns from 650ns if apply this patch. This is not
>>>>>>> perfect solution but better than now.
>>>>>>>
>>>>>>> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
>>>>>>> ---
>>>>>>> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
>>>>>>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> your changing a core rk3399 property here, so I'd really like to get
>>>>>> input from other board stakeholders on this before applying a core
>>>>>> change.
>>>>>>
>>>>>> Could you either include the submitters of other rk3399-boards in the
>>>>>> recipient list so that they're aware or limit the change to rockpro64 for
>>>>>> the time being (aka overriding the property in the board-dts) please?
>>>>>>
>>>>>
>>>>> OK, I'm adding other boards members.
>>>>> by ./scripts/get_maintainer.pl arch/arm64/boot/dts/rockchip/rk3399-*.dts
>>>>>
>>>>>
>>>>> RockPro64 directly connect UART2 pins of RK3399 to external connector.
>>>>> I think maybe other RK3399 boards are facing same problem, but I cannot
>>>>> check it because I have RockPro64 only...
>>>>>
>>>>> I'm happy if someone tell me other boards situation.
>>>>
>>>> I'm pulling out other rockchip boards momentarily to see what kind of
>>>> population we have.
>>>>
>>>> Note these are not all running 5.x kernels, however none of them have
>>>> the UART2 drive levels modified to my knowledge, and regardless, none
>>>> show over 100 ns.
>>>>
>>>> board: rise/fall
>>>>
>>>> rk3399-roc-pc: 90ns/90ns
>>>> rk3399-rockpro64 V2.0: 90ns/45ns
>>>> rk3399-rockpro64 V2.1: 40ns/41ns
>>>>
>>>> Please make sure there's not a large amount of flux or something
>>>> around the terminals on your board, that seems excessively high.
>>>>
>>>
>>> Thank you for valuable information. For more deeply discussion,
>>> I tried other conditions and watch the rise/fall times.
>>>
>>> 1) Not connect
>>> The rise/fall times are 40ns/5ns when nothing connect (impedance is
>>> very high) to external pin of RockPro64.
>>>
>>> What UART device are you using with RockPro64? If you use some device
>>> with RockPro64 and board shows rise/fall times = 90ns/45ns, my device
>>> is not suitable for RockPro64 by some reason. So it's better to drop
>>> my patch.
>>
>> The adapter is an FTDI FT232RL breakout board, attached with some
>> generic Dupont connector jumpers.
>> Interesting your RockPro is showing this symptom, perhaps there is a
>> cold solder joint somewhere introducing resistance?
>>
>>>
>>> 2) Other SoC
>>> I have other SoC board rk3328-rock64, Rock64 shows rise/fall times =
>>> 90ns/80ns when same UART-USB device is connected to UART pin.
>>
>> I measured similar on my Rock64 as well.
>>
>>>
>>> I think it shows rk3399's (or RockPro64's?) drive strength is a little
>>> weak. So it's better to increase the drive strength of UART of rk3399.
>>
>> I do not think this is a bad idea generally, it simply allows for more
>> available current from the interface. I'll let others be the judge of
>> that, however.
>>
>>>
>>> Best Regards,
>>> Katsuhiro Suzuki
>>>
>>>>>
>>>>> Best Regards,
>>>>> Katsuhiro Suzuki
>>>>>
>>>>>
>>>>>> Thanks
>>>>>> Heiko
>>>>>>
>>>>>>
>>>>>>
>>>>>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>>> index beaa92744a64..e3c8f91ead50 100644
>>>>>>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>>> @@ -2000,6 +2000,11 @@
>>>>>>> drive-strength = <8>;
>>>>>>> };
>>>>>>>
>>>>>>> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
>>>>>>> + bias-pull-up;
>>>>>>> + drive-strength = <12>;
>>>>>>> + };
>>>>>>> +
>>>>>>> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
>>>>>>> bias-pull-up;
>>>>>>> drive-strength = <18>;
>>>>>>> @@ -2521,8 +2526,8 @@
>>>>>>> uart2c {
>>>>>>> uart2c_xfer: uart2c-xfer {
>>>>>>> rockchip,pins =
>>>>>>> - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
>>>>>>> - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
>>>>>>> + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
>>>>>>> + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
>>>>>>> };
>>>>>>> };
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Linux-rockchip mailing list
>>>>> Linux-rockchip@lists.infradead.org
>>>>> http://lists.infradead.org/mailman/listinfo/linux-rockchip
>>>>
>>>>
>>>
>
> _______________________________________________
> Linux-rockchip mailing list
> Linux-rockchip@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rockchip
>
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-03 20:41 ` Tony McKahan
@ 2019-03-04 13:59 ` Katsuhiro Suzuki
2019-03-26 13:39 ` Katsuhiro Suzuki
0 siblings, 1 reply; 12+ messages in thread
From: Katsuhiro Suzuki @ 2019-03-04 13:59 UTC (permalink / raw)
To: Tony McKahan, Robin Murphy
Cc: Heiko Stuebner, Viresh Kumar, Linus Walleij, linux-kernel,
Klaus Goger, Manivannan Sadhasivam, Brian Norris, linux-rockchip,
Shawn Lin, Akash Gajjar, Vicente Bergas, Levin Du,
Ezequiel Garcia, linux-arm-kernel, Shohei Maruyama,
Matthias Brugger, Tomeu Vizoso, Dmitry Torokhov,
Douglas Anderson, Jakob Unterwurzacher, Oskari Lemmela,
Enric Balletbo i Serra, Christoph Muellner
Hello Tony, Robin,
On 2019/03/04 5:41, Tony McKahan wrote:
> On Sun, Mar 3, 2019 at 2:51 PM Robin Murphy <robin.murphy@arm.com> wrote:
>>
>> On 2019-03-03 6:45 pm, Tony McKahan wrote:
>>> Hello Katsushiro,
>>>
>>> On Sun, Mar 3, 2019 at 12:31 PM Katsuhiro Suzuki
>>> <katsuhiro@katsuster.net> wrote:
>>>>
>>>> Hello Tony,
>>>>
>>>> On 2019/03/04 0:13, Tony McKahan wrote:
>>>>> On Sun, Mar 3, 2019 at 9:04 AM Katsuhiro Suzuki <katsuhiro@katsuster.net> wrote:
>>>>>>
>>>>>> Hello Heiko,
>>>>>>
>>>>>> Thank you for comments.
>>>>>>
>>>>>> On 2019/03/03 22:19, Heiko Stuebner wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
>>>>>>>> This patch increases drive strength of UART2 from 3mA to 12mA for
>>>>>>>> getting more faster rising edge.
>>>>>>>>
>>>>>>>> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
>>>>>>>> this setting, a bit width of UART is about 667ns.
>>>>>>>>
>>>>>>>> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
>>>>>>>> converter), falling time of RockPro64 UART2 is 40ns, but riging time
>>>>>>>> is over 650ns. So UART receiver will get wrong data, because receiver
>>>>>>>> read intermediate data of rising edge.
>>>>>>>>
>>>>>>>> Rising time becomes 300ns from 650ns if apply this patch. This is not
>>>>>>>> perfect solution but better than now.
>>>>>>>>
>>>>>>>> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
>>>>>>>> ---
>>>>>>>> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
>>>>>>>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>>>>>>
>>>>>>> your changing a core rk3399 property here, so I'd really like to get
>>>>>>> input from other board stakeholders on this before applying a core
>>>>>>> change.
>>>>>>>
>>>>>>> Could you either include the submitters of other rk3399-boards in the
>>>>>>> recipient list so that they're aware or limit the change to rockpro64 for
>>>>>>> the time being (aka overriding the property in the board-dts) please?
>>>>>>>
>>>>>>
>>>>>> OK, I'm adding other boards members.
>>>>>> by ./scripts/get_maintainer.pl arch/arm64/boot/dts/rockchip/rk3399-*.dts
>>>>>>
>>>>>>
>>>>>> RockPro64 directly connect UART2 pins of RK3399 to external connector.
>>>>>> I think maybe other RK3399 boards are facing same problem, but I cannot
>>>>>> check it because I have RockPro64 only...
>>>>>>
>>>>>> I'm happy if someone tell me other boards situation.
>>>>>
>>>>> I'm pulling out other rockchip boards momentarily to see what kind of
>>>>> population we have.
>>>>>
>>>>> Note these are not all running 5.x kernels, however none of them have
>>>>> the UART2 drive levels modified to my knowledge, and regardless, none
>>>>> show over 100 ns.
>>>>>
>>>>> board: rise/fall
>>>>>
>>>>> rk3399-roc-pc: 90ns/90ns
>>>>> rk3399-rockpro64 V2.0: 90ns/45ns
>>>>> rk3399-rockpro64 V2.1: 40ns/41ns
>>
>> I'm having to eyeball off a 20MHz analog scope (thank goodness for "yes"
>> being able to generate a nice periodic signal), but for my NanoPC-T4
>> with a cheap eBay FT232R adapter both rise and fall times are certainly
>> <100ns. FWIW I've not noticed any issues with letting the Bluetooth
>> interface on UART0 run flat-out at 4Mbaud either.
>>
Robin, Thanks a lot. Your results show that cold solder (or some
electric parts on board) of my RockPro64 is broken or something wrong.
>>>>>
>>>>> Please make sure there's not a large amount of flux or something
>>>>> around the terminals on your board, that seems excessively high.
>>>>>
>>>>
>>>> Thank you for valuable information. For more deeply discussion,
>>>> I tried other conditions and watch the rise/fall times.
>>>>
>>>> 1) Not connect
>>>> The rise/fall times are 40ns/5ns when nothing connect (impedance is
>>>> very high) to external pin of RockPro64.
>>>>
>>>> What UART device are you using with RockPro64? If you use some device
>>>> with RockPro64 and board shows rise/fall times = 90ns/45ns, my device
>>>> is not suitable for RockPro64 by some reason. So it's better to drop
>>>> my patch.
>>>
>>> The adapter is an FTDI FT232RL breakout board, attached with some
>>> generic Dupont connector jumpers.
>>> Interesting your RockPro is showing this symptom, perhaps there is a
>>> cold solder joint somewhere introducing resistance?
>>>
>>>>
>>>> 2) Other SoC
>>>> I have other SoC board rk3328-rock64, Rock64 shows rise/fall times =
>>>> 90ns/80ns when same UART-USB device is connected to UART pin.
>>>
>>> I measured similar on my Rock64 as well.
>>>
Tony, thanks for your info about environment.
It seems my RockPro64 problem. I don't have enough electronic knowledge,
but try to check my RockPro64 as much as I can.
>>>>
>>>> I think it shows rk3399's (or RockPro64's?) drive strength is a little
>>>> weak. So it's better to increase the drive strength of UART of rk3399.
>>>
>>> I do not think this is a bad idea generally, it simply allows for more
>>> available current from the interface. I'll let others be the judge of
>>> that, however.
>>
>> There may be RK3399 users who would care about the possible EMI impact,
>> so it's probably still best to limit such a change to boards which
>> definitely need it.
>>
>
> Ah, good point.
>
> As to speeds achievable, I've only run into drive level issues with
> SD/SDIO, but that's all the way up at 25-50 MHz.
My patch has bad effects for EMI issues of all RK3399 boards.
So conclusion is, my patch should be dropped. Sorry for confusing.
Best Regards,
Katsuhiro Suzuki
>
> Tony
>
>> Robin.
>>
>>>
>>>>
>>>> Best Regards,
>>>> Katsuhiro Suzuki
>>>>
>>>>>>
>>>>>> Best Regards,
>>>>>> Katsuhiro Suzuki
>>>>>>
>>>>>>
>>>>>>> Thanks
>>>>>>> Heiko
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>>>> index beaa92744a64..e3c8f91ead50 100644
>>>>>>>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>>>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>>>> @@ -2000,6 +2000,11 @@
>>>>>>>> drive-strength = <8>;
>>>>>>>> };
>>>>>>>>
>>>>>>>> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
>>>>>>>> + bias-pull-up;
>>>>>>>> + drive-strength = <12>;
>>>>>>>> + };
>>>>>>>> +
>>>>>>>> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
>>>>>>>> bias-pull-up;
>>>>>>>> drive-strength = <18>;
>>>>>>>> @@ -2521,8 +2526,8 @@
>>>>>>>> uart2c {
>>>>>>>> uart2c_xfer: uart2c-xfer {
>>>>>>>> rockchip,pins =
>>>>>>>> - <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up>,
>>>>>>>> - <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none>;
>>>>>>>> + <4 RK_PC3 RK_FUNC_1 &pcfg_pull_up_12ma>,
>>>>>>>> + <4 RK_PC4 RK_FUNC_1 &pcfg_pull_none_12ma>;
>>>>>>>> };
>>>>>>>> };
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Linux-rockchip mailing list
>>>>>> Linux-rockchip@lists.infradead.org
>>>>>> http://lists.infradead.org/mailman/listinfo/linux-rockchip
>>>>>
>>>>>
>>>>
>
> _______________________________________________
> Linux-rockchip mailing list
> Linux-rockchip@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rockchip
>
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2
2019-03-04 13:59 ` Katsuhiro Suzuki
@ 2019-03-26 13:39 ` Katsuhiro Suzuki
0 siblings, 0 replies; 12+ messages in thread
From: Katsuhiro Suzuki @ 2019-03-26 13:39 UTC (permalink / raw)
To: Tony McKahan, Robin Murphy
Cc: Heiko Stuebner, Viresh Kumar, Linus Walleij, linux-kernel,
Klaus Goger, Manivannan Sadhasivam, Brian Norris, linux-rockchip,
Shawn Lin, Akash Gajjar, Vicente Bergas, Levin Du,
Ezequiel Garcia, linux-arm-kernel, Shohei Maruyama,
Matthias Brugger, Tomeu Vizoso, Dmitry Torokhov,
Douglas Anderson, Jakob Unterwurzacher, Oskari Lemmela,
Enric Balletbo i Serra, Christoph Muellner
Hello Tony, Robin,
I continue to investigate UART TX rising time problem. Recently, I found
one of cause of this problem.
In my environment, this problem occurred on linux-next only. U-Boot does
not face it. So I compared settings between U-Boot and linux-next. After
I found GRF_IO_VSEL (address 0xff77e640) register is differ.
Would you tell me what value is stored into this register?
My RockPro64, initially 0x00000000 is set but 0x00000003 is set during
linux boot. UART TX rising time becomes fine if set both bit 1 and bit 3
or clear both bits.
Best Regards,
On 2019/03/04 22:59, Katsuhiro Suzuki wrote:
> Hello Tony, Robin,
>
> On 2019/03/04 5:41, Tony McKahan wrote:
>> On Sun, Mar 3, 2019 at 2:51 PM Robin Murphy <robin.murphy@arm.com> wrote:
>>>
>>> On 2019-03-03 6:45 pm, Tony McKahan wrote:
>>>> Hello Katsushiro,
>>>>
>>>> On Sun, Mar 3, 2019 at 12:31 PM Katsuhiro Suzuki
>>>> <katsuhiro@katsuster.net> wrote:
>>>>>
>>>>> Hello Tony,
>>>>>
>>>>> On 2019/03/04 0:13, Tony McKahan wrote:
>>>>>> On Sun, Mar 3, 2019 at 9:04 AM Katsuhiro Suzuki
>>>>>> <katsuhiro@katsuster.net> wrote:
>>>>>>>
>>>>>>> Hello Heiko,
>>>>>>>
>>>>>>> Thank you for comments.
>>>>>>>
>>>>>>> On 2019/03/03 22:19, Heiko Stuebner wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> Am Sonntag, 3. März 2019, 13:27:05 CET schrieb Katsuhiro Suzuki:
>>>>>>>>> This patch increases drive strength of UART2 from 3mA to 12mA for
>>>>>>>>> getting more faster rising edge.
>>>>>>>>>
>>>>>>>>> RockPro64 is using a very high speed rate (1.5Mbps) for UART2. In
>>>>>>>>> this setting, a bit width of UART is about 667ns.
>>>>>>>>>
>>>>>>>>> In my environment (RockPro64 UART2 with FTDI FT232RL UART-USB
>>>>>>>>> converter), falling time of RockPro64 UART2 is 40ns, but riging
>>>>>>>>> time
>>>>>>>>> is over 650ns. So UART receiver will get wrong data, because
>>>>>>>>> receiver
>>>>>>>>> read intermediate data of rising edge.
>>>>>>>>>
>>>>>>>>> Rising time becomes 300ns from 650ns if apply this patch. This
>>>>>>>>> is not
>>>>>>>>> perfect solution but better than now.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
>>>>>>>>> ---
>>>>>>>>> arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 +++++++--
>>>>>>>>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>>>>>>>
>>>>>>>> your changing a core rk3399 property here, so I'd really like to
>>>>>>>> get
>>>>>>>> input from other board stakeholders on this before applying a core
>>>>>>>> change.
>>>>>>>>
>>>>>>>> Could you either include the submitters of other rk3399-boards
>>>>>>>> in the
>>>>>>>> recipient list so that they're aware or limit the change to
>>>>>>>> rockpro64 for
>>>>>>>> the time being (aka overriding the property in the board-dts)
>>>>>>>> please?
>>>>>>>>
>>>>>>>
>>>>>>> OK, I'm adding other boards members.
>>>>>>> by ./scripts/get_maintainer.pl
>>>>>>> arch/arm64/boot/dts/rockchip/rk3399-*.dts
>>>>>>>
>>>>>>>
>>>>>>> RockPro64 directly connect UART2 pins of RK3399 to external
>>>>>>> connector.
>>>>>>> I think maybe other RK3399 boards are facing same problem, but I
>>>>>>> cannot
>>>>>>> check it because I have RockPro64 only...
>>>>>>>
>>>>>>> I'm happy if someone tell me other boards situation.
>>>>>>
>>>>>> I'm pulling out other rockchip boards momentarily to see what kind of
>>>>>> population we have.
>>>>>>
>>>>>> Note these are not all running 5.x kernels, however none of them have
>>>>>> the UART2 drive levels modified to my knowledge, and regardless, none
>>>>>> show over 100 ns.
>>>>>>
>>>>>> board: rise/fall
>>>>>>
>>>>>> rk3399-roc-pc: 90ns/90ns
>>>>>> rk3399-rockpro64 V2.0: 90ns/45ns
>>>>>> rk3399-rockpro64 V2.1: 40ns/41ns
>>>
>>> I'm having to eyeball off a 20MHz analog scope (thank goodness for "yes"
>>> being able to generate a nice periodic signal), but for my NanoPC-T4
>>> with a cheap eBay FT232R adapter both rise and fall times are certainly
>>> <100ns. FWIW I've not noticed any issues with letting the Bluetooth
>>> interface on UART0 run flat-out at 4Mbaud either.
>>>
>
> Robin, Thanks a lot. Your results show that cold solder (or some
> electric parts on board) of my RockPro64 is broken or something wrong.
>
>
>>>>>>
>>>>>> Please make sure there's not a large amount of flux or something
>>>>>> around the terminals on your board, that seems excessively high.
>>>>>>
>>>>>
>>>>> Thank you for valuable information. For more deeply discussion,
>>>>> I tried other conditions and watch the rise/fall times.
>>>>>
>>>>> 1) Not connect
>>>>> The rise/fall times are 40ns/5ns when nothing connect (impedance is
>>>>> very high) to external pin of RockPro64.
>>>>>
>>>>> What UART device are you using with RockPro64? If you use some device
>>>>> with RockPro64 and board shows rise/fall times = 90ns/45ns, my device
>>>>> is not suitable for RockPro64 by some reason. So it's better to drop
>>>>> my patch.
>>>>
>>>> The adapter is an FTDI FT232RL breakout board, attached with some
>>>> generic Dupont connector jumpers.
>>>> Interesting your RockPro is showing this symptom, perhaps there is a
>>>> cold solder joint somewhere introducing resistance?
>>>>
>>>>>
>>>>> 2) Other SoC
>>>>> I have other SoC board rk3328-rock64, Rock64 shows rise/fall times =
>>>>> 90ns/80ns when same UART-USB device is connected to UART pin.
>>>>
>>>> I measured similar on my Rock64 as well.
>>>>
>
> Tony, thanks for your info about environment.
>
> It seems my RockPro64 problem. I don't have enough electronic knowledge,
> but try to check my RockPro64 as much as I can.
>
>
>>>>>
>>>>> I think it shows rk3399's (or RockPro64's?) drive strength is a little
>>>>> weak. So it's better to increase the drive strength of UART of rk3399.
>>>>
>>>> I do not think this is a bad idea generally, it simply allows for more
>>>> available current from the interface. I'll let others be the judge of
>>>> that, however.
>>>
>>> There may be RK3399 users who would care about the possible EMI impact,
>>> so it's probably still best to limit such a change to boards which
>>> definitely need it.
>>>
>>
>> Ah, good point.
>>
>> As to speeds achievable, I've only run into drive level issues with
>> SD/SDIO, but that's all the way up at 25-50 MHz.
>
> My patch has bad effects for EMI issues of all RK3399 boards.
>
> So conclusion is, my patch should be dropped. Sorry for confusing.
>
> Best Regards,
> Katsuhiro Suzuki
>
>
>>
>> Tony
>>
>>> Robin.
>>>
>>>>
>>>>>
>>>>> Best Regards,
>>>>> Katsuhiro Suzuki
>>>>>
>>>>>>>
>>>>>>> Best Regards,
>>>>>>> Katsuhiro Suzuki
>>>>>>>
>>>>>>>
>>>>>>>> Thanks
>>>>>>>> Heiko
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>>>>> b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>>>>> index beaa92744a64..e3c8f91ead50 100644
>>>>>>>>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>>>>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>>>>>>> @@ -2000,6 +2000,11 @@
>>>>>>>>> drive-strength = <8>;
>>>>>>>>> };
>>>>>>>>>
>>>>>>>>> + pcfg_pull_up_12ma: pcfg-pull-up-12ma {
>>>>>>>>> + bias-pull-up;
>>>>>>>>> + drive-strength = <12>;
>>>>>>>>> + };
>>>>>>>>> +
>>>>>>>>> pcfg_pull_up_18ma: pcfg-pull-up-18ma {
>>>>>>>>> bias-pull-up;
>>>>>>>>> drive-strength = <18>;
>>>>>>>>> @@ -2521,8 +2526,8 @@
>>>>>>>>> uart2c {
>>>>>>>>> uart2c_xfer: uart2c-xfer {
>>>>>>>>> rockchip,pins =
>>>>>>>>> - <4 RK_PC3 RK_FUNC_1
>>>>>>>>> &pcfg_pull_up>,
>>>>>>>>> - <4 RK_PC4 RK_FUNC_1
>>>>>>>>> &pcfg_pull_none>;
>>>>>>>>> + <4 RK_PC3 RK_FUNC_1
>>>>>>>>> &pcfg_pull_up_12ma>,
>>>>>>>>> + <4 RK_PC4 RK_FUNC_1
>>>>>>>>> &pcfg_pull_none_12ma>;
>>>>>>>>> };
>>>>>>>>> };
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Linux-rockchip mailing list
>>>>>>> Linux-rockchip@lists.infradead.org
>>>>>>> http://lists.infradead.org/mailman/listinfo/linux-rockchip
>>>>>>
>>>>>>
>>>>>
>>
>> _______________________________________________
>> Linux-rockchip mailing list
>> Linux-rockchip@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-rockchip
>>
>>
>
>
^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2019-03-26 13:39 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-03-03 12:27 [PATCH] arm64: dts: rockchip: decrease rising edge time of UART2 Katsuhiro Suzuki
2019-03-03 13:19 ` Heiko Stuebner
2019-03-03 14:03 ` Katsuhiro Suzuki
2019-03-03 15:13 ` Tony McKahan
2019-03-03 17:31 ` Katsuhiro Suzuki
2019-03-03 18:45 ` Tony McKahan
2019-03-03 19:12 ` Tony McKahan
2019-03-04 13:56 ` Katsuhiro Suzuki
2019-03-03 19:50 ` Robin Murphy
2019-03-03 20:41 ` Tony McKahan
2019-03-04 13:59 ` Katsuhiro Suzuki
2019-03-26 13:39 ` Katsuhiro Suzuki
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