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Date:   Wed, 14 Dec 2022 18:19:16 +0200
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Hanna Hawa <hhhawa@amazon.com>
Cc:     jarkko.nikula@linux.intel.com, mika.westerberg@linux.intel.com,
        jsd@semihalf.com, 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
Subject: Re: [PATCH v2 1/1] i2c: designware: use u64 for clock freq to avoid
 u32 multiplication overflow
Message-ID: <Y5n3hDsbbcnHaDHt@smile.fi.intel.com>
References: <20221214154117.65714-1-hhhawa@amazon.com>
 <Y5n13HLzvMIy3RVh@smile.fi.intel.com>
 <Y5n3PisM+snF8cTJ@smile.fi.intel.com>
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On Wed, Dec 14, 2022 at 06:18:07PM +0200, Andy Shevchenko wrote:
> On Wed, Dec 14, 2022 at 06:12:12PM +0200, Andy Shevchenko wrote:
> > On Wed, Dec 14, 2022 at 03:41:17PM +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.
> > > 
> > > Make the ic_clk to be u64 parameter to avoid the overflow.
> > 
> > Below my comment, after addressing it,
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
> Sorry, was too quick. I have to withdraw my tag since this patch obviously
> breaks a compilation for Intel Quark chip.

ld: drivers/i2c/busses/i2c-designware-common.o: in function `i2c_dw_scl_hcnt':
i2c-designware-common.c:(.text+0x5fe): undefined reference to `__udivdi3'
ld: i2c-designware-common.c:(.text+0x634): undefined reference to `__udivdi3'
ld: drivers/i2c/busses/i2c-designware-common.o: in function `i2c_dw_scl_lcnt':
i2c-designware-common.c:(.text+0x679): undefined reference to `__udivdi3'

> Please, test it carefully and submit new version when it will be ready.

-- 
With Best Regards,
Andy Shevchenko