| Message ID | 201312050054.39327.heiko@sntech.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Heiko, On Thursday 05 of December 2013 00:54:38 Heiko Stübner wrote: > Commit 60e93575476f (serial: samsung: enable clock before clearing pending > interrupts during init) added handling of the controller clock during init. > > On most systems this clock is also one of the baud_clock sources and > possibly used by the earlycon and thus already enabled by the bootloader. > > Therefore a gap exists between s3c24xx_serial_init_port disabling the > clock and an attached console reenabling it, making the transition from > earlycon to regular console possibly hang the system - as seen on my > S3C2442 based Freerunner today. > > Therefore move the disabling of the clock from s3c24xx_serial_init_port > below the uart port registration, effectively creating an overlap and > keeping the clock running non-stop if the console wants to grab this port. > > Signed-off-by: Heiko Stuebner <heiko@sntech.de> > --- > drivers/tty/serial/samsung.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) Makes sense. Reviewed-by: Tomasz Figa <t.figa@samsung.com> Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Greg, just wanted to ask about the state of this patch. I can see it in your branch named "fixes" [0] but it seems it hasn't made its way into the kernel neither during the 3.13-rcs or with your 3.14-pull [1]. Thanks Heiko [0] https://git.kernel.org/cgit/linux/kernel/git/gregkh/tty.git/log/?h=fixes [1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bcee63488ece9a0fca8be19951428a7b41001e66 Am Donnerstag, 5. Dezember 2013, 00:54:38 schrieb Heiko Stübner: > Commit 60e93575476f (serial: samsung: enable clock before clearing pending > interrupts during init) added handling of the controller clock during init. > > On most systems this clock is also one of the baud_clock sources and > possibly used by the earlycon and thus already enabled by the bootloader. > > Therefore a gap exists between s3c24xx_serial_init_port disabling the > clock and an attached console reenabling it, making the transition from > earlycon to regular console possibly hang the system - as seen on my > S3C2442 based Freerunner today. > > Therefore move the disabling of the clock from s3c24xx_serial_init_port > below the uart port registration, effectively creating an overlap and > keeping the clock running non-stop if the console wants to grab this port. > > Signed-off-by: Heiko Stuebner <heiko@sntech.de> > --- > drivers/tty/serial/samsung.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c > index c1af04d..9cd706d 100644 > --- a/drivers/tty/serial/samsung.c > +++ b/drivers/tty/serial/samsung.c > @@ -1209,7 +1209,6 @@ static int s3c24xx_serial_init_port(struct > s3c24xx_uart_port *ourport, > > /* reset the fifos (and setup the uart) */ > s3c24xx_serial_resetport(port, cfg); > - clk_disable_unprepare(ourport->clk); > return 0; > } > > @@ -1287,6 +1286,13 @@ static int s3c24xx_serial_probe(struct > platform_device *pdev) uart_add_one_port(&s3c24xx_uart_drv, > &ourport->port); > platform_set_drvdata(pdev, &ourport->port); > > + /* > + * Deactivate the clock enabled in s3c24xx_serial_init_port here, > + * so that a potential re-enablement through the pm-callback overlaps > + * and keeps the clock enabled in this case. > + */ > + clk_disable_unprepare(ourport->clk); > + > #ifdef CONFIG_SAMSUNG_CLOCK > ret = device_create_file(&pdev->dev, &dev_attr_clock_source); > if (ret < 0) -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jan 21, 2014 at 03:26:42PM +0100, Heiko Stübner wrote: > Hi Greg, > > just wanted to ask about the state of this patch. I can see it in your branch > named "fixes" [0] but it seems it hasn't made its way into the kernel neither > during the 3.13-rcs or with your 3.14-pull [1]. > > > Thanks > Heiko > > > [0] https://git.kernel.org/cgit/linux/kernel/git/gregkh/tty.git/log/?h=fixes > [1] > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bcee63488ece9a0fca8be19951428a7b41001e66 Ah crap, I missed this, sorry, I'll get it to Linus in time for 3.14-final, sorry about that. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c index c1af04d..9cd706d 100644 --- a/drivers/tty/serial/samsung.c +++ b/drivers/tty/serial/samsung.c @@ -1209,7 +1209,6 @@ static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport, /* reset the fifos (and setup the uart) */ s3c24xx_serial_resetport(port, cfg); - clk_disable_unprepare(ourport->clk); return 0; } @@ -1287,6 +1286,13 @@ static int s3c24xx_serial_probe(struct platform_device *pdev) uart_add_one_port(&s3c24xx_uart_drv, &ourport->port); platform_set_drvdata(pdev, &ourport->port); + /* + * Deactivate the clock enabled in s3c24xx_serial_init_port here, + * so that a potential re-enablement through the pm-callback overlaps + * and keeps the clock enabled in this case. + */ + clk_disable_unprepare(ourport->clk); + #ifdef CONFIG_SAMSUNG_CLOCK ret = device_create_file(&pdev->dev, &dev_attr_clock_source); if (ret < 0)
Commit 60e93575476f (serial: samsung: enable clock before clearing pending interrupts during init) added handling of the controller clock during init. On most systems this clock is also one of the baud_clock sources and possibly used by the earlycon and thus already enabled by the bootloader. Therefore a gap exists between s3c24xx_serial_init_port disabling the clock and an attached console reenabling it, making the transition from earlycon to regular console possibly hang the system - as seen on my S3C2442 based Freerunner today. Therefore move the disabling of the clock from s3c24xx_serial_init_port below the uart port registration, effectively creating an overlap and keeping the clock running non-stop if the console wants to grab this port. Signed-off-by: Heiko Stuebner <heiko@sntech.de> --- drivers/tty/serial/samsung.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)