Quoting Chris Wilson (2018-09-27 13:35:47)
> Quoting Jani Nikula (2018-09-27 10:40:23)
> > Slightly verbose, but does away with hand rolled shifts and provides
> > static checking that the values fit the mask.
> >
> > Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> > ---
> > @@ -4650,11 +4650,11 @@ enum {
> > #define _PP_ON_DELAYS 0x61208
> > #define PP_ON_DELAYS(pps_idx) _MMIO_PPS(pps_idx, _PP_ON_DELAYS)
> > #define PANEL_PORT_SELECT_MASK GENMASK(31, 30)
> > -#define PANEL_PORT_SELECT_LVDS (0 << 30)
> > -#define PANEL_PORT_SELECT_DPA (1 << 30)
> > -#define PANEL_PORT_SELECT_DPC (2 << 30)
> > -#define PANEL_PORT_SELECT_DPD (3 << 30)
> > -#define PANEL_PORT_SELECT_VLV(port) ((port) << 30)
> > +#define PANEL_PORT_SELECT_LVDS FIELD_PREP(PANEL_PORT_SELECT_MASK, 0)
> > +#define PANEL_PORT_SELECT_DPA FIELD_PREP(PANEL_PORT_SELECT_MASK, 1)
> > +#define PANEL_PORT_SELECT_DPC FIELD_PREP(PANEL_PORT_SELECT_MASK, 2)
> > +#define PANEL_PORT_SELECT_DPD FIELD_PREP(PANEL_PORT_SELECT_MASK, 3)
> > +#define PANEL_PORT_SELECT_VLV(port) FIELD_PREP(PANEL_PORT_SELECT_MASK, port)
>
> Maybe verbose, but it reads far better as giving each field a distinct
> name ties together all the individual options.
>
> Before seeing this I was sceptical about FIELD_PREP, no longer.
>
> Under this construct we aren't using masks per se, but giving a name to
> a group of bits within the register (a field). So I think
>
> #define PANEL_PORT_SELECT GENMASK(31, 30)
> #define PANEL_PORT_SELECT_LVDS FIELD_PREP(PANEL_PORT_SELECT, 0)
>
> is intuitive. Did you do a quick bloatometer to see if gcc code
> generation is affected?
+1 from me for the change as big and for the above detail suggested by
Chris.
Regards, Joonas
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