On Mon, 14 Oct 2013 14:50:30 +0300
ville.syrjala@xxxxxxxxxxxxxxx wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Rounding down when calculating the dot/vco frequencies doesn't make much
> sense. Round to closest should give slightly nicer answers.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_display.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index fbd028e..baa6ef6 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -329,8 +329,8 @@ static void vlv_clock(int refclk, intel_clock_t *clock)
> {
> clock->m = clock->m1 * clock->m2;
> clock->p = clock->p1 * clock->p2;
> - clock->vco = refclk * clock->m / clock->n;
> - clock->dot = clock->vco / clock->p;
> + clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
> + clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> }
>
> /**
> @@ -430,8 +430,8 @@ static void pineview_clock(int refclk, intel_clock_t *clock)
> {
> clock->m = clock->m2 + 2;
> clock->p = clock->p1 * clock->p2;
> - clock->vco = refclk * clock->m / clock->n;
> - clock->dot = clock->vco / clock->p;
> + clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
> + clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> }
>
> static uint32_t i9xx_dpll_compute_m(struct dpll *dpll)
> @@ -443,8 +443,8 @@ static void i9xx_clock(int refclk, intel_clock_t *clock)
> {
> clock->m = i9xx_dpll_compute_m(clock);
> clock->p = clock->p1 * clock->p2;
> - clock->vco = refclk * clock->m / (clock->n + 2);
> - clock->dot = clock->vco / clock->p;
> + clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n + 2);
> + clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> }
>
> #define INTELPllInvalid(s) do { /* DRM_DEBUG(s); */ return false; } while (0)
Reviewed-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
--
Jesse Barnes, Intel Open Source Technology Center
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