[PATCH 4.14-4.17 1/2] earlycon: Initialize port->uartclk based on clock-frequency property

[PATCH 4.14-4.17 1/2] earlycon: Initialize port->uartclk based on clock-frequency property

[Rafał Miłecki]

From: Michal Simek <michal.simek@xilinx.com>

commit 814453adea7d081ad8917aa0f32d6a14165a3563 upstream.

On DT based platforms when current-speed property is present baudrate
is setup. Also port->uartclk is initialized to bogus BASE_BAUD * 16
value. Drivers like uartps/ns16550 contain logic when baudrate and
uartclk is used for baudrate calculation.

The patch is reading optional clock-frequency property to replace bogus
BASE_BAUD * 16 calculation to have proper baudrate calculation.

[-stable comment: commit 31cb9a8575ca ("earlycon: initialise baud field
 of earlycon device structure") has changed 8250_early.c behavior which
 now tries to setup UART speed. Ignoring clock-frequency results in
 wrong value of calculated divisor & malformed early console output.]

Fixes: 31cb9a8575ca ("earlycon: initialise baud field of earlycon device structure")
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[rmilecki: add -stable comment and Fixes tag]
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 drivers/tty/serial/earlycon.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index ac667b47f199..05ba1875bb3e 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -289,6 +289,10 @@ int __init of_setup_earlycon(const struct earlycon_id *match,
 	if (val)
 		early_console_dev.baud = be32_to_cpu(*val);
 
+	val = of_get_flat_dt_prop(node, "clock-frequency", NULL);
+	if (val)
+		port->uartclk = be32_to_cpu(*val);
+
 	if (options) {
 		early_console_dev.baud = simple_strtoul(options, NULL, 0);
 		strlcpy(early_console_dev.options, options,
-- 
2.13.7

[PATCH 4.14-4.17 2/2] earlycon: Remove hardcoded port->uartclk initialization in of_setup_earlycon

[Rafał Miłecki]

From: Michal Simek <michal.simek@xilinx.com>

commit 182ead3e418a20328b73152b8e81fc8b4cac3b0b upstream.

There is no reason to initialize uartclk to BASE_BAUD * 16 for DT based
systems.

[-stable comment: commit 31cb9a8575ca ("earlycon: initialise baud field
 of earlycon device structure") has changed 8250_early.c behavior which
 now tries to setup UART speed.
 Already-backported upstream commit 0ff3ab701963 ("serial:  8250_early:
 Only set divisor if valid clk & baud") handles properly uartclk not
 being set but it still requires backporting fix for wrong uartclk val.
 This fixes malformed early console output on arch-es with BASE_BAUD.]

Fixes: 31cb9a8575ca ("earlycon: initialise baud field of earlycon device structure")
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Matt Redfearn <matt.redfearn@mips.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[rmilecki: add -stable comment and Fixes tag]
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 drivers/tty/serial/earlycon.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index 05ba1875bb3e..7b0a3a1688e8 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -254,7 +254,6 @@ int __init of_setup_earlycon(const struct earlycon_id *match,
 		return -ENXIO;
 	}
 	port->mapbase = addr;
-	port->uartclk = BASE_BAUD * 16;
 
 	val = of_get_flat_dt_prop(node, "reg-offset", NULL);
 	if (val)
-- 
2.13.7

Re: [PATCH 4.14-4.17 1/2] earlycon: Initialize port->uartclk based on clock-frequency property

[Greg Kroah-Hartman]

On Mon, Sep 24, 2018 at 12:34:45AM +0200, Rafał Miłecki wrote:
> From: Michal Simek <michal.simek@xilinx.com>
> 
> commit 814453adea7d081ad8917aa0f32d6a14165a3563 upstream.
> 
> On DT based platforms when current-speed property is present baudrate
> is setup. Also port->uartclk is initialized to bogus BASE_BAUD * 16
> value. Drivers like uartps/ns16550 contain logic when baudrate and
> uartclk is used for baudrate calculation.
> 
> The patch is reading optional clock-frequency property to replace bogus
> BASE_BAUD * 16 calculation to have proper baudrate calculation.
> 
> [-stable comment: commit 31cb9a8575ca ("earlycon: initialise baud field
>  of earlycon device structure") has changed 8250_early.c behavior which
>  now tries to setup UART speed. Ignoring clock-frequency results in
>  wrong value of calculated divisor & malformed early console output.]

Thanks for both of these, now queued up.

greg k-h