linux-kernel - Re: [PATCH 5/6] clk: qcom: gdsc: Do not check for disabled status on votable gdscs

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Message-ID: <20151201015323.GF17532@codeaurora.org>
Date:	Mon, 30 Nov 2015 17:53:23 -0800
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Rajendra Nayak <rnayak@...eaurora.org>
Cc:	mturquette@...libre.com, linux-kernel@...r.kernel.org,
	linux-clk@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 5/6] clk: qcom: gdsc: Do not check for disabled status on
 votable gdscs

On 11/26, Rajendra Nayak wrote:
> Some gdscs might be controlled via voting registers and might not
> really disable when the kernel intends to disable them (due to other
> votes keeping them enabled)
> Mark these gdscs with a flag for we do not check/wait on a disable
> status for these gdscs within the kernel disable callback.
> 
> Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
> ---
>  drivers/clk/qcom/gcc-msm8996.c  |  4 ++++
>  drivers/clk/qcom/gdsc.c         |  4 ++++
>  drivers/clk/qcom/gdsc.h         | 15 ++++++++-------
>  drivers/clk/qcom/mmcc-msm8996.c |  3 +++
>  4 files changed, 19 insertions(+), 7 deletions(-)

We should have this patch before adding the gdscs that use it.
Prevents any bisect hole.

>  static struct gdsc usb30_gdsc = {
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index fb2e43c..984537f 100644
> --- a/drivers/clk/qcom/gdsc.c
> +++ b/drivers/clk/qcom/gdsc.c
> @@ -65,6 +65,10 @@ static int gdsc_toggle_logic(struct gdsc *sc, bool en)
>  	if (ret)
>  		return ret;
>  
> +	/* If disabling votable gdscs, don't poll on status */
> +	if ((sc->flags & VOTABLE) && !en)
> +		return 0;
> +

There's an explicit delay of 100uS on the disable path for
votable gdscs in the downstream code. I don't see that here.

>  	timeout = jiffies + usecs_to_jiffies(TIMEOUT_US);
>  
>  	if (sc->gds_hw_ctrl) {
> diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
> index 66a43be..91cbb09 100644
> --- a/drivers/clk/qcom/gdsc.h
> +++ b/drivers/clk/qcom/gdsc.h
> @@ -20,13 +20,6 @@
>  struct regmap;
>  struct reset_controller_dev;
>  
> -/* Powerdomain allowable state bitfields */
> -#define PWRSTS_OFF		BIT(0)
> -#define PWRSTS_RET		BIT(1)
> -#define PWRSTS_ON		BIT(2)
> -#define PWRSTS_OFF_ON		(PWRSTS_OFF | PWRSTS_ON)
> -#define PWRSTS_RET_ON		(PWRSTS_RET | PWRSTS_ON)
> -
>  /**
>   * struct gdsc - Globally Distributed Switch Controller
>   * @pd: generic power domain
> @@ -49,6 +42,14 @@ struct gdsc {
>  	unsigned int			*cxcs;
>  	unsigned int			cxc_count;
>  	const u8			pwrsts;
> +/* Powerdomain allowable state bitfields */
> +#define PWRSTS_OFF		BIT(0)
> +#define PWRSTS_RET		BIT(1)
> +#define PWRSTS_ON		BIT(2)
> +#define PWRSTS_OFF_ON		(PWRSTS_OFF | PWRSTS_ON)
> +#define PWRSTS_RET_ON		(PWRSTS_RET | PWRSTS_ON)

Yes! We should have done this already. I guess I'm ok combining
it with this patch.

> +	const u8			flags;
> +#define VOTABLE		BIT(0)
>  	struct reset_controller_dev	*rcdev;
>  	unsigned int			*resets;
>  	unsigned int			reset_count;

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