On Thu, Jun 18, 2015 at 06:19:44PM +0800, YH Huang wrote: > On Fri, 2015-06-12 at 12:20 +0200, Thierry Reding wrote: > > On Thu, May 21, 2015 at 09:29:24PM +0800, YH Huang wrote: [...] > > > +#define DISP_PWM_CON_1 0x14 > > > +#define PWM_PERIOD_MASK 0xfff > > > +#define PWM_PERIOD_MAX 0x00000fff > > > > Same here. PWM_PERIOD_MAX isn't actually used anywhere, so perhaps just > > drop it altogether. But see also below... > > > > > +/* Shift log2(PWM_PERIOD_MAX + 1) as divisor */ > > > +#define PWM_PERIOD_BIT_SHIFT 12 > > > > I wasn't very clear about this in my earlier review, so let me try to > > explain why I think this is confusing. You use this as a divisor, but > > you encode it as a shift. It's also PWM_PERIOD_MAX + 1, so I think it > > would make more sense to drop this, keep PWM_PERIOD_MAX as above and > > then replace the > > > > >> PWM_PERIOD_BIT_SHIFT > > > > below by > > > > / (PWM_PERIOD_MAX + 1) > > > > Maybe I can change in this way: > Remove this: #define PWM_PERIOD_MAX 0x00000fff > Using ">> PWM_PERIOD_BIT_SHIFT" is faster than "/ (PWM_PERIOD_MAX + 1)" > Is this right?
The compiler should be able to optimize the division to a shift, so both will likely result in the same code. But I don't mind much either way as long as we don't define two symbols for essentially the same value. Thierry
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