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Date:   Thu, 24 Feb 2022 15:01:27 +0200
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Subject: Re: [PATCH -next] i2c: designware: Fix improper usage of readl
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To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Jan Dabros <jsd@semihalf.com>
Cc:     linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
        wsa@kernel.org, rrangel@chromium.org, upstream@semihalf.com,
        kernel test robot <lkp@intel.com>
References: <20220218133348.628962-1-jsd@semihalf.com>
 <YhZNu0pHKiK9Vf55@smile.fi.intel.com>
From:   Jarkko Nikula <jarkko.nikula@linux.intel.com>
In-Reply-To: <YhZNu0pHKiK9Vf55@smile.fi.intel.com>
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On 2/23/22 17:07, Andy Shevchenko wrote:
> On Fri, Feb 18, 2022 at 02:33:48PM +0100, Jan Dabros wrote:
>> Kernel test robot reported incorrect type in argument 1 of readl(), but
>> more importantly it brought attention that MMIO accessor shouldn't be
>> used in this case, since req->hdr.status is part of a command-response
>> buffer in system memory.
>>
>> Since its value may be altered by PSP outside of the scope of current
>> thread (somehow similar to IRQ handler case), we need to use
>> READ_ONCE() to ensure compiler won't optimize this call.
>>
>> Fix also 'status' variable type to reflect that corresponding field in
>> command-response buffer is platform-independent u32.
> 
> Thanks for the fix, seems reasonable to me.
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>