Re: [PATCH v3 4/4] misc: atmel_tclib: get and use slow clock

[Daniel Lezcano]

On 08/11/2015 11:38 AM, Alexandre Belloni wrote:
> From: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
>
> Commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system
> hang") added a workaround for the slow clock as it is not properly handled
> by its users.
>
> Get and use the slow clock as it is necessary for the timer counters.
>
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
> Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Thierry Reding <thierry.reding@xxxxxxxxx>
> Cc: linux-pwm@xxxxxxxxxxxxxxx
>
>   drivers/clocksource/tcb_clksrc.c |  8 ++++++++
>   drivers/misc/atmel_tclib.c       |  4 ++++
>   drivers/pwm/pwm-atmel-tcb.c      | 23 ++++++++++++++++-------
>   include/linux/atmel_tc.h         |  1 +
>   4 files changed, 29 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
> index b9b7277173c2..969ba03633b0 100644
> --- a/drivers/clocksource/tcb_clksrc.c
> +++ b/drivers/clocksource/tcb_clksrc.c
> @@ -188,6 +188,13 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
>   	ret = clk_prepare_enable(t2_clk);
>   	if (ret)
>   		return ret;
> +
> +	ret = clk_prepare_enable(tc->slow_clk);
> +	if (ret) {
> +		clk_disable_unprepare(t2_clk);
> +		return ret;
> +	}
> +
>   	clk_disable(t2_clk);

Do you need t2_clk to be enabled in order to enable tc->slow_clk ?

>   	clkevt.regs = tc->regs;
> @@ -200,6 +207,7 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
>   	ret = request_irq(irq, ch2_irq, IRQF_TIMER, "tc_clkevt", &clkevt);
>   	if (ret) {
>   		clk_unprepare(t2_clk);
> +		clk_disable_unprepare(tc->slow_clk);
>   		return ret;
>   	}
>
> diff --git a/drivers/misc/atmel_tclib.c b/drivers/misc/atmel_tclib.c
> index 0ca05c3ec8d6..ac24a4bd63f7 100644
> --- a/drivers/misc/atmel_tclib.c
> +++ b/drivers/misc/atmel_tclib.c

[ ... ]

> @@ -387,9 +387,9 @@ static int atmel_tcb_pwm_probe(struct platform_device *pdev)
>
>   	tcbpwm = devm_kzalloc(&pdev->dev, sizeof(*tcbpwm), GFP_KERNEL);
>   	if (tcbpwm == NULL) {
> -		atmel_tc_free(tc);
> +		err = -ENOMEM;
>   		dev_err(&pdev->dev, "failed to allocate memory\n");
> -		return -ENOMEM;
> +		goto err_free_tc;
>   	}
>
>   	tcbpwm->chip.dev = &pdev->dev;
> @@ -400,17 +400,24 @@ static int atmel_tcb_pwm_probe(struct platform_device *pdev)
>   	tcbpwm->chip.npwm = NPWM;
>   	tcbpwm->tc = tc;
>
> +	err = clk_prepare_enable(tc->slow_clk);
> +	if (err)
> +		goto err_free_tc;
> +
>   	spin_lock_init(&tcbpwm->lock);
>
>   	err = pwmchip_add(&tcbpwm->chip);
> -	if (err < 0) {
> -		atmel_tc_free(tc);
> -		return err;
> -	}
> +	if (err < 0)
> +		goto err_free_tc;
>
>   	platform_set_drvdata(pdev, tcbpwm);
>
>   	return 0;
> +
> +err_free_tc:
> +	atmel_tc_free(tc);
> +
> +	return err;

What about clk_unprepare_disable(tc->slow_clk) ?

>   }

[ ... ]


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