linux-kernel - Re: [PATCH v4 1/3] soc: fsl: handle RCPM errata A-008646 on SoC LS1021A

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Date:   Mon, 23 Nov 2020 19:13:09 -0600
From:   Li Yang <leoyang.li@....com>
To:     Ran Wang <ran.wang_1@....com>
Cc:     Shawn Guo <shawnguo@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, lkml <linux-kernel@...r.kernel.org>,
        Biwen Li <biwen.li@....com>
Subject: Re: [PATCH v4 1/3] soc: fsl: handle RCPM errata A-008646 on SoC LS1021A

On Mon, Nov 2, 2020 at 1:37 AM Ran Wang <ran.wang_1@....com> wrote:
>
> From: Biwen Li <biwen.li@....com>
>
> Hardware issue:
> - Reading register RCPM_IPPDEXPCR1 always return zero, this causes
>   system firmware could not get correct information and wrongly do
>   clock gating for all wakeup source IP during system suspend. Then
>   those IPs will never get chance to wake system.
>
> Workaround:
> - Copy register RCPM_IPPDEXPCR1's setting to register SCFG_SPARECR8
>   to allow system firmware's psci method read it and do things accordingly.
>
> Signed-off-by: Biwen Li <biwen.li@....com>
> Signed-off-by: Ran Wang <ran.wang_1@....com>

Applied for next.  Thanks.

> ---
> Change in v4:
>  - Replace property 'fsl,ippdexpcr1-alt-reg' with compatible checking as the
>    workaround trigger condition.
>
> Change in v3:
>  - Add  copy_ippdexpcr1_setting(), simplize workaournd's implementation
>    according to binding update.
>  - Minor update on commit message.
>
> Change in v2:
>  - Update commit message to be more clear.
>  - Replace device_property_read_u32_array() with syscon_regmap_lookup_by_phandle_args()
>    to make code simpler.
>
>  drivers/soc/fsl/rcpm.c | 35 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/soc/fsl/rcpm.c b/drivers/soc/fsl/rcpm.c
> index a093dbe..4ace28c 100644
> --- a/drivers/soc/fsl/rcpm.c
> +++ b/drivers/soc/fsl/rcpm.c
> @@ -2,7 +2,7 @@
>  //
>  // rcpm.c - Freescale QorIQ RCPM driver
>  //
> -// Copyright 2019 NXP
> +// Copyright 2019-2020 NXP
>  //
>  // Author: Ran Wang <ran.wang_1@....com>
>
> @@ -22,6 +22,28 @@ struct rcpm {
>         bool            little_endian;
>  };
>
> +#define  SCFG_SPARECR8 0x051c
> +
> +static void copy_ippdexpcr1_setting(u32 val)
> +{
> +       struct device_node *np;
> +       void __iomem *regs;
> +       u32 reg_val;
> +
> +       np = of_find_compatible_node(NULL, NULL, "fsl,ls1021a-scfg");
> +       if (!np)
> +               return;
> +
> +       regs = of_iomap(np, 0);
> +       if (!regs)
> +               return;
> +
> +       reg_val = ioread32be(regs + SCFG_SPARECR8);
> +       iowrite32be(val | reg_val, regs + SCFG_SPARECR8);
> +
> +       iounmap(regs);
> +}
> +
>  /**
>   * rcpm_pm_prepare - performs device-level tasks associated with power
>   * management, such as programming related to the wakeup source control.
> @@ -90,6 +112,17 @@ static int rcpm_pm_prepare(struct device *dev)
>                         tmp |= ioread32be(address);
>                         iowrite32be(tmp, address);
>                 }
> +               /*
> +                * Workaround of errata A-008646 on SoC LS1021A:
> +                * There is a bug of register ippdexpcr1.
> +                * Reading configuration register RCPM_IPPDEXPCR1
> +                * always return zero. So save ippdexpcr1's value
> +                * to register SCFG_SPARECR8.And the value of
> +                * ippdexpcr1 will be read from SCFG_SPARECR8.
> +                */
> +               if (dev_of_node(dev) && (i == 1))
> +                       if (of_device_is_compatible(np, "fsl,ls1021a-rcpm"))
> +                               copy_ippdexpcr1_setting(tmp);
>         }
>
>         return 0;
> --
> 2.7.4
>