diff mbox series

arm: mvebu: a38x: Define supported UART baudrates

Message ID 20210811080804.17770-1-pali@kernel.org
State Accepted
Commit ead4864fa6ccd552b1c2b6941e4b16ed6128b02f
Delegated to: Stefan Roese
Headers show
Series arm: mvebu: a38x: Define supported UART baudrates | expand

Commit Message

Pali Rohár Aug. 11, 2021, 8:08 a.m. UTC
Define all standard baudrates plus 3 non-standard high speed:
3125000 4000000 5150000

3125000 matches divisor 5 with 250 MHz TCLK and divisor 4 with 200 MHz TCLK.
4000000 is the rounded value for divisor 4 with 250 MHz TCLK (3906250) and
divisor 3 with 200 MHz TCLK (4166666).

5150000 is the rounded value (5208333) for divisor 3 with 250 MHz TCLK.
Testing showed that rounded value is more stable then exactly calculated.
And it is the highest possible baudrate which is stable on A38x platform.

Any other baudrate values above 2500000 are unstable, which is reason why
e.g. standard value 3000000 is not defined, and it is needed to use
non-standard value 3125000.

Tested all defined UART baudrates on Turris Omnia (A38x with 250 MHz TCLK).

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 include/configs/mv-common.h | 9 +++++++++
 1 file changed, 9 insertions(+)

Comments

Marek Behún Aug. 11, 2021, 11 a.m. UTC | #1
Reviewed-by: Marek Behún <marek.behun@nic.cz>
Stefan Roese Aug. 11, 2021, 2:17 p.m. UTC | #2
On 11.08.21 10:08, Pali Rohár wrote:
> Define all standard baudrates plus 3 non-standard high speed:
> 3125000 4000000 5150000
> 
> 3125000 matches divisor 5 with 250 MHz TCLK and divisor 4 with 200 MHz TCLK.
> 4000000 is the rounded value for divisor 4 with 250 MHz TCLK (3906250) and
> divisor 3 with 200 MHz TCLK (4166666).
> 
> 5150000 is the rounded value (5208333) for divisor 3 with 250 MHz TCLK.
> Testing showed that rounded value is more stable then exactly calculated.
> And it is the highest possible baudrate which is stable on A38x platform.
> 
> Any other baudrate values above 2500000 are unstable, which is reason why
> e.g. standard value 3000000 is not defined, and it is needed to use
> non-standard value 3125000.
> 
> Tested all defined UART baudrates on Turris Omnia (A38x with 250 MHz TCLK).
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>

Reviewed-by: Stefan Roese <sr@denx.de>

Thanks,
Stefan

> ---
>   include/configs/mv-common.h | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/include/configs/mv-common.h b/include/configs/mv-common.h
> index d61c90a43156..53d7acbb1034 100644
> --- a/include/configs/mv-common.h
> +++ b/include/configs/mv-common.h
> @@ -39,6 +39,15 @@
>   #define CONFIG_SYS_NS16550_COM1		MV_UART_CONSOLE_BASE
>   #endif
>   
> +#if defined(CONFIG_ARMADA_38X) && !defined(CONFIG_SYS_BAUDRATE_TABLE)
> +#define CONFIG_SYS_BAUDRATE_TABLE	{ 300, 600, 1200, 1800, 2400, 4800, \
> +					  9600, 19200, 38400, 57600, 115200, \
> +					  230400, 460800, 500000, 576000, \
> +					  921600, 1000000, 1152000, 1500000, \
> +					  2000000, 2500000, 3125000, 4000000, \
> +					  5150000 }
> +#endif
> +
>   /* auto boot */
>   
>   /*
> 


Viele Grüße,
Stefan
Stefan Roese Sept. 1, 2021, 9:07 a.m. UTC | #3
On 11.08.21 10:08, Pali Rohár wrote:
> Define all standard baudrates plus 3 non-standard high speed:
> 3125000 4000000 5150000
> 
> 3125000 matches divisor 5 with 250 MHz TCLK and divisor 4 with 200 MHz TCLK.
> 4000000 is the rounded value for divisor 4 with 250 MHz TCLK (3906250) and
> divisor 3 with 200 MHz TCLK (4166666).
> 
> 5150000 is the rounded value (5208333) for divisor 3 with 250 MHz TCLK.
> Testing showed that rounded value is more stable then exactly calculated.
> And it is the highest possible baudrate which is stable on A38x platform.
> 
> Any other baudrate values above 2500000 are unstable, which is reason why
> e.g. standard value 3000000 is not defined, and it is needed to use
> non-standard value 3125000.
> 
> Tested all defined UART baudrates on Turris Omnia (A38x with 250 MHz TCLK).
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>

Applied to u-boot-marvell/master

Thanks,
Stefan

> ---
>   include/configs/mv-common.h | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/include/configs/mv-common.h b/include/configs/mv-common.h
> index d61c90a43156..53d7acbb1034 100644
> --- a/include/configs/mv-common.h
> +++ b/include/configs/mv-common.h
> @@ -39,6 +39,15 @@
>   #define CONFIG_SYS_NS16550_COM1		MV_UART_CONSOLE_BASE
>   #endif
>   
> +#if defined(CONFIG_ARMADA_38X) && !defined(CONFIG_SYS_BAUDRATE_TABLE)
> +#define CONFIG_SYS_BAUDRATE_TABLE	{ 300, 600, 1200, 1800, 2400, 4800, \
> +					  9600, 19200, 38400, 57600, 115200, \
> +					  230400, 460800, 500000, 576000, \
> +					  921600, 1000000, 1152000, 1500000, \
> +					  2000000, 2500000, 3125000, 4000000, \
> +					  5150000 }
> +#endif
> +
>   /* auto boot */
>   
>   /*
> 


Viele Grüße,
Stefan
diff mbox series

Patch

diff --git a/include/configs/mv-common.h b/include/configs/mv-common.h
index d61c90a43156..53d7acbb1034 100644
--- a/include/configs/mv-common.h
+++ b/include/configs/mv-common.h
@@ -39,6 +39,15 @@ 
 #define CONFIG_SYS_NS16550_COM1		MV_UART_CONSOLE_BASE
 #endif
 
+#if defined(CONFIG_ARMADA_38X) && !defined(CONFIG_SYS_BAUDRATE_TABLE)
+#define CONFIG_SYS_BAUDRATE_TABLE	{ 300, 600, 1200, 1800, 2400, 4800, \
+					  9600, 19200, 38400, 57600, 115200, \
+					  230400, 460800, 500000, 576000, \
+					  921600, 1000000, 1152000, 1500000, \
+					  2000000, 2500000, 3125000, 4000000, \
+					  5150000 }
+#endif
+
 /* auto boot */
 
 /*