linux-kernel - Re: [PATCH 3/7] clk: zynqmp: Warn user if clock user are more than allowed

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Date:   Thu, 21 Nov 2019 15:31:15 +0100
From:   Michael Tretter <m.tretter@...gutronix.de>
To:     Rajan Vaja <rajan.vaja@...inx.com>
Cc:     mturquette@...libre.com, sboyd@...nel.org, robh+dt@...nel.org,
        mark.rutland@....com, michal.simek@...inx.com,
        jolly.shah@...inx.com, dan.carpenter@...cle.com,
        gustavo@...eddedor.com, nava.manne@...inx.com,
        ravi.patel@...inx.com, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kernel@...gutronix.de,
        m.tretter@...gutronix.de
Subject: Re: [PATCH 3/7] clk: zynqmp: Warn user if clock user are more than
 allowed

On Tue, 12 Nov 2019 05:16:16 -0800, Rajan Vaja wrote:
> Warn user if clock is used by more than allowed devices.
> This check is done by firmware and returns respective
> error code. Upon receiving error code for excessive user,
> warn user for the same.
> 
> This change is done to restrict VPLL use count. It is
> assumed that VPLL is used by one user only.
> 
> Signed-off-by: Michal Simek <michal.simek@...inx.com>
> Signed-off-by: Rajan Vaja <rajan.vaja@...inx.com>
> ---
>  drivers/clk/zynqmp/pll.c             | 9 ++++++---
>  drivers/firmware/xilinx/zynqmp.c     | 2 ++
>  include/linux/firmware/xlnx-zynqmp.h | 1 +
>  3 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/zynqmp/pll.c b/drivers/clk/zynqmp/pll.c
> index a541397..2f4ccaa 100644
> --- a/drivers/clk/zynqmp/pll.c
> +++ b/drivers/clk/zynqmp/pll.c
> @@ -188,9 +188,12 @@ static int zynqmp_pll_set_rate(struct clk_hw *hw, unsigned long rate,
>  		frac = (parent_rate * f) / FRAC_DIV;
>  
>  		ret = eemi_ops->clock_setdivider(clk_id, m);
> -		if (ret)
> -			pr_warn_once("%s() set divider failed for %s, ret = %d\n",
> -				     __func__, clk_name, ret);
> +		if (ret) {
> +			if (ret == -EUSERS)
> +				WARN(1, "More than allowed devices are using the %s, which is forbidden\n", clk_name);
> +			pr_err("%s() set divider failed for %s, ret = %d\n",
> +			       __func__, clk_name, ret);
> +		}

In case of -EUSERS this prints the warning and the error. This seems a
bit excessive to me. Isn't it enough to leave the existing
pr_warn_once() for the new error code? If not, then add a new warning
for the -EUSERS error, but leave the existing warning as it is.

Michael

>  
>  		eemi_ops->ioctl(0, IOCTL_SET_PLL_FRAC_DATA, clk_id, f, NULL);
>  
> diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
> index 0137bf3..ecc339d 100644
> --- a/drivers/firmware/xilinx/zynqmp.c
> +++ b/drivers/firmware/xilinx/zynqmp.c
> @@ -53,6 +53,8 @@ static int zynqmp_pm_ret_code(u32 ret_status)
>  		return -EACCES;
>  	case XST_PM_ABORT_SUSPEND:
>  		return -ECANCELED;
> +	case XST_PM_MULT_USER:
> +		return -EUSERS;
>  	case XST_PM_INTERNAL:
>  	case XST_PM_CONFLICT:
>  	case XST_PM_INVALID_NODE:
> diff --git a/include/linux/firmware/xlnx-zynqmp.h b/include/linux/firmware/xlnx-zynqmp.h
> index 25bedd2..f019d1c 100644
> --- a/include/linux/firmware/xlnx-zynqmp.h
> +++ b/include/linux/firmware/xlnx-zynqmp.h
> @@ -96,6 +96,7 @@ enum pm_ret_status {
>  	XST_PM_INVALID_NODE,
>  	XST_PM_DOUBLE_REQ,
>  	XST_PM_ABORT_SUSPEND,
> +	XST_PM_MULT_USER = 2008,
>  };
>  
>  enum pm_ioctl_id {