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Date:   Sun, 22 Mar 2020 16:22:24 -0400
From:   Sasha Levin <sashal@kernel.org>
To:     20200116141849.73955-1-r.czerwinski@pengutronix.de
Cc:     Rouven Czerwinski <r.czerwinski@pengutronix.de>,
        s.hauer@pengutronix.de, shawnguo@kernel.org,
        Ahmad Fatoum <a.fatoum@pengutronix.de>,
        linux-kernel@vger.kernel.org, linux-imx@nxp.com,
        kernel@pengutronix.de, festevam@gmail.com,
        linux-arm-kernel@lists.infradead.org,
        Lucas Stach <l.stach@pengutronix.de>, stable@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] ARM: imx: build v7_cpu_resume() unconditionally
Message-ID: <20200322202224.GQ4189@sasha-vm>
References: <20200116141849.73955-1-r.czerwinski@pengutronix.de>
 <20200322185022.GA82867@workstation.tuxnet>
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On Sun, Mar 22, 2020 at 07:50:22PM +0100, Clemens Gruber wrote:
>Hi,
>
>On Thu, Jan 16, 2020 at 03:18:49PM +0100, Rouven Czerwinski wrote:
>> From: Ahmad Fatoum <a.fatoum@pengutronix.de>
>>
>> This function is not only needed by the platform suspend code, but is also
>> reused as the CPU resume function when the ARM cores can be powered down
>> completely in deep idle, which is the case on i.MX6SX and i.MX6UL(L).
>>
>> Providing the static inline stub whenever CONFIG_SUSPEND is disabled means
>> that those platforms will hang on resume from cpuidle if suspend is disabled.
>>
>> So there are two problems:
>>
>>   - The static inline stub masks the linker error
>>   - The function is not available where needed
>>
>> Fix both by just building the function unconditionally, when
>> CONFIG_SOC_IMX6 is enabled. The actual code is three instructions long,
>> so it's arguably ok to just leave it in for all i.MX6 kernel configurations.
>>
>> Fixes: 05136f0897b5 ("ARM: imx: support arm power off in cpuidle for i.mx6sx")
>> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>> Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
>> ---
>>  arch/arm/mach-imx/Makefile       |  2 ++
>>  arch/arm/mach-imx/common.h       |  4 ++--
>>  arch/arm/mach-imx/resume-imx6.S  | 24 ++++++++++++++++++++++++
>>  arch/arm/mach-imx/suspend-imx6.S | 14 --------------
>>  4 files changed, 28 insertions(+), 16 deletions(-)
>>  create mode 100644 arch/arm/mach-imx/resume-imx6.S
>>
>> diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile
>> index 35ff620537e6..03506ce46149 100644
>> --- a/arch/arm/mach-imx/Makefile
>> +++ b/arch/arm/mach-imx/Makefile
>> @@ -91,6 +91,8 @@ AFLAGS_suspend-imx6.o :=-Wa,-march=armv7-a
>>  obj-$(CONFIG_SOC_IMX6) += suspend-imx6.o
>>  obj-$(CONFIG_SOC_IMX53) += suspend-imx53.o
>>  endif
>> +AFLAGS_resume-imx6.o :=-Wa,-march=armv7-a
>> +obj-$(CONFIG_SOC_IMX6) += resume-imx6.o
>>  obj-$(CONFIG_SOC_IMX6) += pm-imx6.o
>>
>>  obj-$(CONFIG_SOC_IMX1) += mach-imx1.o
>> diff --git a/arch/arm/mach-imx/common.h b/arch/arm/mach-imx/common.h
>> index 912aeceb4ff8..5aa5796cff0e 100644
>> --- a/arch/arm/mach-imx/common.h
>> +++ b/arch/arm/mach-imx/common.h
>> @@ -109,17 +109,17 @@ void imx_cpu_die(unsigned int cpu);
>>  int imx_cpu_kill(unsigned int cpu);
>>
>>  #ifdef CONFIG_SUSPEND
>> -void v7_cpu_resume(void);
>>  void imx53_suspend(void __iomem *ocram_vbase);
>>  extern const u32 imx53_suspend_sz;
>>  void imx6_suspend(void __iomem *ocram_vbase);
>>  #else
>> -static inline void v7_cpu_resume(void) {}
>>  static inline void imx53_suspend(void __iomem *ocram_vbase) {}
>>  static const u32 imx53_suspend_sz;
>>  static inline void imx6_suspend(void __iomem *ocram_vbase) {}
>>  #endif
>>
>> +void v7_cpu_resume(void);
>> +
>>  void imx6_pm_ccm_init(const char *ccm_compat);
>>  void imx6q_pm_init(void);
>>  void imx6dl_pm_init(void);
>> diff --git a/arch/arm/mach-imx/resume-imx6.S b/arch/arm/mach-imx/resume-imx6.S
>> new file mode 100644
>> index 000000000000..5bd1ba7ef15b
>> --- /dev/null
>> +++ b/arch/arm/mach-imx/resume-imx6.S
>> @@ -0,0 +1,24 @@
>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
>> +/*
>> + * Copyright 2014 Freescale Semiconductor, Inc.
>> + */
>> +
>> +#include <linux/linkage.h>
>> +#include <asm/assembler.h>
>> +#include <asm/asm-offsets.h>
>> +#include <asm/hardware/cache-l2x0.h>
>> +#include "hardware.h"
>> +
>> +/*
>> + * The following code must assume it is running from physical address
>> + * where absolute virtual addresses to the data section have to be
>> + * turned into relative ones.
>> + */
>> +
>> +ENTRY(v7_cpu_resume)
>> +	bl	v7_invalidate_l1
>> +#ifdef CONFIG_CACHE_L2X0
>> +	bl	l2c310_early_resume
>> +#endif
>> +	b	cpu_resume
>> +ENDPROC(v7_cpu_resume)
>> diff --git a/arch/arm/mach-imx/suspend-imx6.S b/arch/arm/mach-imx/suspend-imx6.S
>> index 062391ff13da..1eabf2d2834b 100644
>> --- a/arch/arm/mach-imx/suspend-imx6.S
>> +++ b/arch/arm/mach-imx/suspend-imx6.S
>> @@ -327,17 +327,3 @@ resume:
>>
>>  	ret	lr
>>  ENDPROC(imx6_suspend)
>> -
>> -/*
>> - * The following code must assume it is running from physical address
>> - * where absolute virtual addresses to the data section have to be
>> - * turned into relative ones.
>> - */
>> -
>> -ENTRY(v7_cpu_resume)
>> -	bl	v7_invalidate_l1
>> -#ifdef CONFIG_CACHE_L2X0
>> -	bl	l2c310_early_resume
>> -#endif
>> -	b	cpu_resume
>> -ENDPROC(v7_cpu_resume)
>> --
>> 2.25.0
>
>This patch broke the build for our i.MX6 kernel.
>
>I am referring to commits 512a928aff in mainline and
>7199cb65bb in linux-stable.
>
>In our kernel, neither CONFIG_PM nor CONFIG_SUSPEND are set. Therefore,
>ARM_CPU_SUSPEND is also unset, which means that sleep.S (containing
>cpu_resume) is not built.
>
>With this patch, ld reports the following error:
>arch/arm/mach-imx/resume-imx6.o: in function `v7_cpu_resume':
>(.text+0x8): undefined reference to `cpu_resume'

Is this a problem with Linus's tree as well?

-- 
Thanks,
Sasha