| Message ID | 1435252100-8234-1-git-send-email-damien.lespiau@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
2015-06-25 14:08 GMT-03:00 Damien Lespiau <damien.lespiau@intel.com>: > We can't improve a 0 deviation, so when we find such a divider, skip the > remaining ones they won't be better. > > This short-circuit the search for 34 of the 373 test frequencies in the > corresponding i-g-t test (tools/skl_compute_wrpll) > > Suggested-by: Paulo Zanoni <paulo.r.zanoni@intel.com> > Signed-off-by: Damien Lespiau <damien.lespiau@intel.com> > --- > This patch has to be applied after patch 12 and 13 for the recent SKL DPLL > series. > > drivers/gpu/drm/i915/intel_ddi.c | 21 ++++++++++++++++----- > 1 file changed, 16 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c > index f6b3ccc..45116d8 100644 > --- a/drivers/gpu/drm/i915/intel_ddi.c > +++ b/drivers/gpu/drm/i915/intel_ddi.c > @@ -1122,7 +1122,11 @@ static void skl_wrpll_context_init(struct skl_wrpll_context *ctx) > #define SKL_DCO_MAX_PDEVIATION 100 > #define SKL_DCO_MAX_NDEVIATION 600 > > -static void skl_wrpll_try_divider(struct skl_wrpll_context *ctx, > +/* > + * Returns true if we're sure to have found the definitive divider (ie > + * deviation == 0). > + */ > +static bool skl_wrpll_try_divider(struct skl_wrpll_context *ctx, > uint64_t central_freq, > uint64_t dco_freq, > unsigned int divider) > @@ -1141,6 +1145,10 @@ static void skl_wrpll_try_divider(struct skl_wrpll_context *ctx, > ctx->dco_freq = dco_freq; > ctx->p = divider; > } > + > + /* we can't improve a 0 deviation */ > + if (deviation == 0) > + return true; Took me a while to understand why this was exactly here :) > /* negative deviation */ > } else if (deviation < SKL_DCO_MAX_NDEVIATION && > deviation < ctx->min_deviation) { > @@ -1150,6 +1158,7 @@ static void skl_wrpll_try_divider(struct skl_wrpll_context *ctx, > ctx->p = divider; > } > > + return false; > } > > static void skl_wrpll_get_multipliers(unsigned int p, > @@ -1311,13 +1320,15 @@ skl_ddi_calculate_wrpll(int clock /* in Hz */, > unsigned int p = dividers[d].list[i]; > uint64_t dco_freq = p * afe_clock; > > - skl_wrpll_try_divider(&ctx, > - dco_central_freq[dco], > - dco_freq, > - p); > + if (skl_wrpll_try_divider(&ctx, > + dco_central_freq[dco], > + dco_freq, > + p)) > + goto skip_remaining_dividers; Bikeshed: instead of touching skl_wrpll_try_divider(), you could just: if (ctx.min_deviation == 0) goto skip_remaining_dividers; That would keep the logic of the optimization restricted to this function. IMHO, much simpler. With or without changes: Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com> > } > } > > +skip_remaining_dividers: > /* > * If a solution is found with an even divider, prefer > * this one. > -- > 2.1.0 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
On Fri, Jun 26, 2015 at 02:18:39PM -0300, Paulo Zanoni wrote: > > @@ -1311,13 +1320,15 @@ skl_ddi_calculate_wrpll(int clock /* in Hz */, > > unsigned int p = dividers[d].list[i]; > > uint64_t dco_freq = p * afe_clock; > > > > - skl_wrpll_try_divider(&ctx, > > - dco_central_freq[dco], > > - dco_freq, > > - p); > > + if (skl_wrpll_try_divider(&ctx, > > + dco_central_freq[dco], > > + dco_freq, > > + p)) > > + goto skip_remaining_dividers; > > Bikeshed: instead of touching skl_wrpll_try_divider(), you could just: > > if (ctx.min_deviation == 0) goto skip_remaining_dividers; > > That would keep the logic of the optimization restricted to this > function. IMHO, much simpler. > > With or without changes: Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com> I like that, v2 it is!
Tested-By: Intel Graphics QA PRTS (Patch Regression Test System Contact: shuang.he@intel.com)
Task id: 6633
-------------------------------------Summary-------------------------------------
Platform Delta drm-intel-nightly Series Applied
ILK 302/302 302/302
SNB 312/316 312/316
IVB 343/343 343/343
BYT 287/287 287/287
HSW 380/380 380/380
-------------------------------------Detailed-------------------------------------
Platform Test drm-intel-nightly Series Applied
Note: You need to pay more attention to line start with '*'
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c index f6b3ccc..45116d8 100644 --- a/drivers/gpu/drm/i915/intel_ddi.c +++ b/drivers/gpu/drm/i915/intel_ddi.c @@ -1122,7 +1122,11 @@ static void skl_wrpll_context_init(struct skl_wrpll_context *ctx) #define SKL_DCO_MAX_PDEVIATION 100 #define SKL_DCO_MAX_NDEVIATION 600 -static void skl_wrpll_try_divider(struct skl_wrpll_context *ctx, +/* + * Returns true if we're sure to have found the definitive divider (ie + * deviation == 0). + */ +static bool skl_wrpll_try_divider(struct skl_wrpll_context *ctx, uint64_t central_freq, uint64_t dco_freq, unsigned int divider) @@ -1141,6 +1145,10 @@ static void skl_wrpll_try_divider(struct skl_wrpll_context *ctx, ctx->dco_freq = dco_freq; ctx->p = divider; } + + /* we can't improve a 0 deviation */ + if (deviation == 0) + return true; /* negative deviation */ } else if (deviation < SKL_DCO_MAX_NDEVIATION && deviation < ctx->min_deviation) { @@ -1150,6 +1158,7 @@ static void skl_wrpll_try_divider(struct skl_wrpll_context *ctx, ctx->p = divider; } + return false; } static void skl_wrpll_get_multipliers(unsigned int p, @@ -1311,13 +1320,15 @@ skl_ddi_calculate_wrpll(int clock /* in Hz */, unsigned int p = dividers[d].list[i]; uint64_t dco_freq = p * afe_clock; - skl_wrpll_try_divider(&ctx, - dco_central_freq[dco], - dco_freq, - p); + if (skl_wrpll_try_divider(&ctx, + dco_central_freq[dco], + dco_freq, + p)) + goto skip_remaining_dividers; } } +skip_remaining_dividers: /* * If a solution is found with an even divider, prefer * this one.
We can't improve a 0 deviation, so when we find such a divider, skip the remaining ones they won't be better. This short-circuit the search for 34 of the 373 test frequencies in the corresponding i-g-t test (tools/skl_compute_wrpll) Suggested-by: Paulo Zanoni <paulo.r.zanoni@intel.com> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com> --- This patch has to be applied after patch 12 and 13 for the recent SKL DPLL series. drivers/gpu/drm/i915/intel_ddi.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-)