linux-kernel - Re: [PATCH] ARM: imx: Drop imx_anatop

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Message-ID: <CAHQ1cqHBzFi80ZCa+jgs0Qy=dMP4yP7am1x-hMTxzb-8Zpok0w@mail.gmail.com>
Date:   Thu, 22 Aug 2019 13:06:05 -0700
From:   Andrey Smirnov <andrew.smirnov@...il.com>
To:     Leonard Crestez <leonard.crestez@....com>
Cc:     Shawn Guo <shawnguo@...nel.org>,
        Fabio Estevam <festevam@...il.com>,
        Chris Healy <cphealy@...il.com>,
        Peter Chen <peter.chen@....com>,
        dl-linux-imx <linux-imx@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Aisheng Dong <aisheng.dong@....com>
Subject: Re: [PATCH] ARM: imx: Drop imx_anatop_init()

On Thu, Aug 22, 2019 at 10:33 AM Leonard Crestez
<leonard.crestez@....com> wrote:
>
> On 31.07.2019 21:01, Andrey Smirnov wrote:
> > With commit b5bbe2235361 ("usb: phy: mxs: Disable external charger
> > detect in mxs_phy_hw_init()") in tree all of the necessary charger
> > setup is done by the USB PHY driver which covers all of the affected
> > i.MX6 SoCs.
> >
> > NOTE: Imx_anatop_init() was also called for i.MX7D, but looking at its
> > datasheet it appears to have a different USB PHY IP block, so
> > executing i.MX6 charger disable configuration seems unnecessary.
> >
> > -void __init imx_anatop_init(void)
> > -{
> > -     anatop = syscon_regmap_lookup_by_compatible("fsl,imx6q-anatop");
> > -     if (IS_ERR(anatop)) {
> > -             pr_err("%s: failed to find imx6q-anatop regmap!\n", __func__);
> > -             return;
> > -     }
>
> This patch breaks suspend on imx6 in linux-next because the "anatop"
> regmap is no longer initialized. This was found via bisect but
> no_console_suspend prints a helpful stack anyway:
>
> (regmap_read) from [<c01226e4>] (imx_anatop_enable_weak2p5+0x28/0x70)
> (imx_anatop_enable_weak2p5) from [<c0122744>]
> (imx_anatop_pre_suspend+0x18/0x64)
> (imx_anatop_pre_suspend) from [<c0124434>] (imx6q_pm_enter+0x60/0x16c)
> (imx6q_pm_enter) from [<c018c8a4>] (suspend_devices_and_enter+0x7d4/0xcbc)
> (suspend_devices_and_enter) from [<c018d544>] (pm_suspend+0x7b8/0x904)
> (pm_suspend) from [<c018b1b4>] (state_store+0x68/0xc8)
>

My bad, completely missed that fact that anatop was a global variable
in  imx_anatop_init(). Sorry about that.

> Minimal fix looks like this:
>
> --- arch/arm/mach-imx/anatop.c
> +++ arch/arm/mach-imx/anatop.c
> @@ -111,6 +111,12 @@ void __init imx_init_revision_from_anatop(void)
>           digprog = readl_relaxed(anatop_base + offset);
>           iounmap(anatop_base);
>
> +       anatop = syscon_regmap_lookup_by_compatible("fsl,imx6q-anatop");
> +       if (IS_ERR(anatop)) {
> +               pr_err("failed to find imx6q-anatop regmap!\n");
> +               return;
> +       }
>
> Since all SOCs that called imx_anatop_init also call
> imx_init_revision_from_anatop this might be an acceptable solution,
> unless there is some limitation preventing early regmap lookup.
>

Would making every function that uses anatop explicitly request it via
syscon_regmap_lookup_by_compatible("fsl,imx6q-anatop") be too much of
a code duplication? This way we won't need to worry if
imx_init_revision_from_anatop() was called before any of them are
used.

Thanks,
Andrey Smirnov