[U-Boot] video: ipu_common: fix build error

[Eric Nelson]

On 09/06/2017 11:01 PM, Lothar Waßmann wrote:
> On Wed, 6 Sep 2017 10:34:33 -0700 Eric Nelson wrote:
>> On 09/05/2017 06:16 PM, Peng Fan wrote:
>>> On Mon, Sep 04, 2017 at 07:48:56PM -0700, Eric Nelson wrote:
>>>> Hi Peng,
>>>>
>>>> Can you tell that I'm hunting a bug in an old version?
>>>>
>>>> I'm seeing a **very** intermittent regression between U-Boot
>>>> versions 2015.07 and 2016.05 and happened to spot something
>>>> in this patch.
>>>>
>>>> On 04/27/2016 07:07 PM, Peng Fan wrote:
>>>>> Some toolchains fail to build
>>>>> "clk->rate = (u64)(clk->parent->rate * 16) / div;"
>>>>> And the cast usage is wrong.
>>>>>
>>>>> Use the following code to fix the issue,
>>>>> "
>>>>>     do_div(parent_rate, div);
>>>>>     clk->rate = parent_rate;
>>>>> "
>>>>>
>>>>> Reported-by: Peter Robinson <pbrobinson at gmail.com>
>>>>> Signed-off-by: Peng Fan <van.freenix at gmail.com>
>>>>> Cc: Stefano Babic <sbabic at denx.de>
>>>>> Cc: Fabio Estevam <fabio.estevam at nxp.com>
>>>>> Cc: Tom Rini <trini at konsulko.com>
>>>>> Cc: Anatolij Gustschin <agust at denx.de>
>>>>> Cc: Peter Robinson <pbrobinson at gmail.com>
>>>>> Reviewed-by: Tom Rini <trini at konsulko.com>
>>>>> Tested-by: Peter Robinson <pbrobinson at gmail.com>
>>>>> ---
>>>>>
>>>>> Hi Peter,
>>>>>
>>>>>    Please help test this patch to see whether this fix your issue or not.
>>>>>    Thanks for pointing out this issue.
>>>>>
>>>>> Thanks,
>>>>> Peng.
>>>>>
>>>>>    drivers/video/ipu_common.c | 4 +++-
>>>>>    1 file changed, 3 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/video/ipu_common.c b/drivers/video/ipu_common.c
>>>>> index 36d4b23..5676a0f 100644
>>>>> --- a/drivers/video/ipu_common.c
>>>>> +++ b/drivers/video/ipu_common.c
>>>>> @@ -352,7 +352,9 @@ static int ipu_pixel_clk_set_rate(struct clk *clk, unsigned long rate)
>>>>>    	 */
>>>>>    	__raw_writel((div / 16) << 16, DI_BS_CLKGEN1(clk->id));
>>>>
>>>> Did we lose a multiply by 16 in this change?
>>>
>>> We already have "parent_rate = (unsigned long long)clk->parent->rate * 16;"
>>> in this function.
>>>
>>
>> Hmmm. So this patch also fixed a bug, since we previously had
>> **two** multiply-by-16's:
>>
> No! The 'second' multiply by 16 used the clk->parent->rate, not the
> 'parent_rate' which was multiplied by 16...
> 
> | parent_rate = (unsigned long long)clk->parent->rate * 16;
> [...]
> | clk->rate = (u64)(clk->parent->rate * 16) / div;
> 

Doh! I clearly missed that.

Thanks Lothar.