[PATCH v2] serial: sifive: enable clocks for UART when probed

[PATCH v2] serial: sifive: enable clocks for UART when probed

[Olof Johansson]

When the PWM driver was changed to disable clocks if no PWMs are enabled,
it ended up also disabling the shared parent with the UART, since the
UART doesn't do any clock enablement on its own.

To avoid these surprises, switch to clk_get_enabled().

Fixes: ace41d7564e655 ("pwm: sifive: Ensure the clk is enabled exactly once per running PWM")
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

---

v2: Switch to devm_clk_enabled() per Uwe's suggestion.

---
 drivers/tty/serial/sifive.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index 5c3a07546a58..4b1d4fe8458e 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -945,7 +945,7 @@ static int sifive_serial_probe(struct platform_device *pdev)
 		return PTR_ERR(base);
 	}
 
-	clk = devm_clk_get(&pdev->dev, NULL);
+	clk = devm_clk_get_enabled(&pdev->dev, NULL);
 	if (IS_ERR(clk)) {
 		dev_err(&pdev->dev, "unable to find controller clock\n");
 		return PTR_ERR(clk);
-- 
2.30.2

Re: [PATCH v2] serial: sifive: enable clocks for UART when probed

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 743 bytes --]

Hello,

On Tue, Sep 20, 2022 at 09:00:18AM -0700, Olof Johansson wrote:
> When the PWM driver was changed to disable clocks if no PWMs are enabled,
> it ended up also disabling the shared parent with the UART, since the
> UART doesn't do any clock enablement on its own.
> 
> To avoid these surprises, switch to clk_get_enabled().
> 
> Fixes: ace41d7564e655 ("pwm: sifive: Ensure the clk is enabled exactly once per running PWM")
> Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH v2] serial: sifive: enable clocks for UART when probed

[Palmer Dabbelt]

On Tue, 20 Sep 2022 09:00:18 PDT (-0700), Olof Johansson wrote:
> When the PWM driver was changed to disable clocks if no PWMs are enabled,
> it ended up also disabling the shared parent with the UART, since the
> UART doesn't do any clock enablement on its own.
>
> To avoid these surprises, switch to clk_get_enabled().
>
> Fixes: ace41d7564e655 ("pwm: sifive: Ensure the clk is enabled exactly once per running PWM")
> Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Cc: Emil Renner Berthing <emil.renner.berthing@canonical.com>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Paul Walmsley <paul.walmsley@sifive.com>
> Signed-off-by: Olof Johansson <olof@lixom.net>
>
> ---
>
> v2: Switch to devm_clk_enabled() per Uwe's suggestion.
>
> ---
>  drivers/tty/serial/sifive.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
> index 5c3a07546a58..4b1d4fe8458e 100644
> --- a/drivers/tty/serial/sifive.c
> +++ b/drivers/tty/serial/sifive.c
> @@ -945,7 +945,7 @@ static int sifive_serial_probe(struct platform_device *pdev)
>  		return PTR_ERR(base);
>  	}
>
> -	clk = devm_clk_get(&pdev->dev, NULL);
> +	clk = devm_clk_get_enabled(&pdev->dev, NULL);
>  	if (IS_ERR(clk)) {
>  		dev_err(&pdev->dev, "unable to find controller clock\n");
>  		return PTR_ERR(clk);

I have one of these lying around somewhere if you need someone to test 
it, but sounds like you had from the v1 email.  Either way

Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>

as this seems better than what was there.

Thanks!