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

[Lothar Waßmann]

Hi,

On Wed, 6 Sep 2017 10:34:33 -0700 Eric Nelson wrote:
> Thanks Peng.
> 
> 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;



Lothar Waßmann