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

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Date:   Thu, 22 Aug 2019 17:33:13 +0000
From:   Leonard Crestez <leonard.crestez@....com>
To:     Andrey Smirnov <andrew.smirnov@...il.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Fabio Estevam <festevam@...il.com>
CC:     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 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)

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.

--
Regards,
Leonard