[PATCH] drm: bridge: cdns-mhdp8546: fix compile warning

[Laurent Pinchart]

On Fri, Sep 25, 2020 at 03:05:52PM +0300, Tomi Valkeinen wrote:
> On 25/09/2020 15:00, Laurent Pinchart wrote:
> > On Fri, Sep 25, 2020 at 10:36:44AM +0300, Tomi Valkeinen wrote:
> >> On 24/09/2020 14:48, Laurent Pinchart wrote:
> >>> Hi Tomi,
> >>>
> >>> Thank you for the patch.
> >>>
> >>> On Wed, Sep 23, 2020 at 11:30:57AM +0300, Tomi Valkeinen wrote:
> >>>> On x64 we get:
> >>>>
> >>>> drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c:751:10: warning: conversion from 'long unsigned int' to 'unsigned int' changes value from '18446744073709551613' to '4294967293' [-Woverflow]
> >>>>
> >>>> The registers are 32 bit, so fix by casting to u32.
> >>>
> >>> I wonder if we need a BIT32 macro... This is a common issue, it would be
> >>> nice to handle it in the macros that define register fields.
> >>
> >> That's probably a good idea. I think
> >>
> >> #define BIT32(nr) (1u << (nr))
> >>
> >> should work correct on all archs. Although I'm not quite sure if nr should be cast to u32, but in my
> >> tests a u64 nr doesn't cause type promotion to u64.
> > 
> > I don't think we need to support nr values larger than 2^32-1 ;-)
> 
> That's true, but we might have:
> 
> u64 nr = 1;
> BIT32(nr)
> 
> Afaics, we don't need to cast nr to u32, but maybe that's still the safe thing to do.
> 
> >> Anyway, I'd like to merge this fix as it is to get rid of the warning for the merge window.
> > 
> > Sounds good to me.
> 
> Was that a reviewed-by? =)

Acked-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

-- 
Regards,

Laurent Pinchart