On 03/19/2015 01:55 PM, Imre Deak wrote: > On Thu, 2015-03-19 at 13:34 -0700, Jesse Barnes wrote: >> On 03/17/2015 02:40 AM, Imre Deak wrote: >>> Prepare chv_find_best_dpll to be used for BXT too, where we want to >>> consider the error between target and calculated frequency too when >>> choosing a better PLL configuration. >>> >>> No functional change. >>> >>> Signed-off-by: Imre Deak <[email protected]> >>> --- >>> drivers/gpu/drm/i915/intel_display.c | 26 ++++++++++++++++++++------ >>> 1 file changed, 20 insertions(+), 6 deletions(-) >>> >>> diff --git a/drivers/gpu/drm/i915/intel_display.c >>> b/drivers/gpu/drm/i915/intel_display.c >>> index 5874512..9ca84a2 100644 >>> --- a/drivers/gpu/drm/i915/intel_display.c >>> +++ b/drivers/gpu/drm/i915/intel_display.c >>> @@ -786,6 +786,16 @@ static bool vlv_PLL_is_optimal(struct drm_device *dev, >>> int target_freq, >>> unsigned int best_error_ppm, >>> unsigned int *error_ppm) >>> { >>> + /* >>> + * For CHV ignore the error and consider only the P value. >>> + * Prefer a bigger P value based on HW requirements. >>> + */ >>> + if (IS_CHERRYVIEW(dev)) { >>> + *error_ppm = 0; >>> + >>> + return calculated_clock->p > best_clock->p; >>> + } >>> + >>> if (WARN_ON_ONCE(!target_freq)) >>> return false; >>> >>> @@ -864,11 +874,13 @@ chv_find_best_dpll(const intel_limit_t *limit, struct >>> intel_crtc *crtc, >>> intel_clock_t *best_clock) >>> { >>> struct drm_device *dev = crtc->base.dev; >>> + unsigned int best_error_ppm; >>> intel_clock_t clock; >>> uint64_t m2; >>> int found = false; >>> >>> memset(best_clock, 0, sizeof(*best_clock)); >>> + best_error_ppm = 1000000; >>> >>> /* >>> * Based on hardware doc, the n always set to 1, and m1 always >>> @@ -882,6 +894,7 @@ chv_find_best_dpll(const intel_limit_t *limit, struct >>> intel_crtc *crtc, >>> for (clock.p2 = limit->p2.p2_fast; >>> clock.p2 >= limit->p2.p2_slow; >>> clock.p2 -= clock.p2 > 10 ? 2 : 1) { >>> + unsigned int error_ppm; >>> >>> clock.p = clock.p1 * clock.p2; >>> >>> @@ -898,12 +911,13 @@ chv_find_best_dpll(const intel_limit_t *limit, struct >>> intel_crtc *crtc, >>> if (!intel_PLL_is_valid(dev, limit, &clock)) >>> continue; >>> >>> - /* based on hardware requirement, prefer bigger p >>> - */ >>> - if (clock.p > best_clock->p) { >>> - *best_clock = clock; >>> - found = true; >>> - } >>> + if (!vlv_PLL_is_optimal(dev, target, &clock, best_clock, >>> + best_error_ppm, &error_ppm)) >>> + continue; >>> + >>> + *best_clock = clock; >>> + best_error_ppm = error_ppm; >>> + found = true; >>> } >>> } >>> >>> >> >> Looking at it again, maybe vlv_PLL_is_better() might be a better name. > > Ok, will change it. > >> Also, could you just make the ppm variable a scratch one and ignore it? >> It just gets set to 0 no matter what, right? > > For CHV yes. But the next patch takes the same function into use in BXT > too, where error_ppm will be set to the actual error, the same way as on > VLV.
Oh right it's a patch *series*. Ignore the noise. :) The rename is optional too; I just had to think about it when I saw >>> + return calculated_clock->p > best_clock->p; since in that case we're really checking whether the new calculated p value is better (higher) than the last one. The _is_optimal() name made me think it should be >= or something. But it's not a big deal. Thanks, Jesse _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
