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Message-ID: <9c663363-49a0-da2f-508b-dbf3906b4d61@linux.intel.com>
Date:   Thu, 22 Dec 2022 17:14:14 +0200
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Subject: Re: [PATCH v5 1/1] i2c: designware: use casting of u64 in clock
 multiplication to avoid overflow
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To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Hanna Hawa <hhhawa@amazon.com>
Cc:     wsa@kernel.org, mika.westerberg@linux.intel.com, jsd@semihalf.com,
        linus.walleij@linaro.org, ben-linux@fluff.org,
        linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
        dwmw@amazon.co.uk, benh@amazon.com, ronenk@amazon.com,
        talel@amazon.com, jonnyc@amazon.com, hanochu@amazon.com,
        farbere@amazon.com, itamark@amazon.com, lareine@amazon.com
References: <20221221195900.23276-1-hhhawa@amazon.com>
 <Y6NnkDwD9UUQ8Ro/@smile.fi.intel.com>
From:   Jarkko Nikula <jarkko.nikula@linux.intel.com>
In-Reply-To: <Y6NnkDwD9UUQ8Ro/@smile.fi.intel.com>
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On 12/21/22 22:07, Andy Shevchenko wrote:
> On Wed, Dec 21, 2022 at 07:59:00PM +0000, Hanna Hawa wrote:
>> From: Lareine Khawaly <lareine@amazon.com>
>>
>> In functions i2c_dw_scl_lcnt() and i2c_dw_scl_hcnt() may have overflow
>> by depending on the values of the given parameters including the ic_clk.
>> For example in our use case where ic_clk is larger than one million,
>> multiplication of ic_clk * 4700 will result in 32 bit overflow.
>>
>> Add cast of u64 to the calculation to avoid multiplication overflow, and
>> use the corresponding define for divide.
> 
> Perfect, thank you!
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>