Hi, Ville. Sorry for taking long to get back to this. Quoting Ville Syrjälä (2024-02-05 12:34:57-03:00) >On Sat, Feb 03, 2024 at 10:25:18AM -0300, Gustavo Sousa wrote: >> Quoting Ville Syrjälä (2024-02-02 16:58:37-03:00) >> >On Fri, Feb 02, 2024 at 10:12:08AM -0300, Gustavo Sousa wrote: >> >> Looks like the name and description of intel_cdclk_needs_modeset() >> >> became inacurate as of commit 59f9e9cab3a1 ("drm/i915: Skip modeset for >> >> cdclk changes if possible"), when it became possible to update the cdclk >> >> without requiring disabling the pipes when only changing the cd2x >> >> divider was enough. >> >> >> >> Later on we also added the same type of support with squash and crawling >> >> with commit 25e0e5ae5610 ("drm/i915/display: Do both crawl and squash >> >> when changing cdclk"), commit d4a23930490d ("drm/i915: Allow cdclk >> >> squasher to be reconfigured live") and commit d62686ba3b54 >> >> ("drm/i915/adl_p: CDCLK crawl support for ADL"). >> >> >> >> As such, update that function's name and documentation to something more >> >> appropriate, since the real checks for requiring modeset are done >> >> elsewhere. >> >> >> >> Signed-off-by: Gustavo Sousa <gustavo.sousa@xxxxxxxxx> >> >> --- >> >> >> >> One thing worth noting here is that, with this change, we are left with an >> >> awkward situation where two function names related to checking changes in cdclk: >> >> >> >> intel_cdclk_params_changed() and intel_cdclk_changed() >> >> >> >> , >> >> >> >> and I find it weird that we have intel_cdclk_changed(), which checks for the >> >> voltage level as well. Shouldn't the voltage level be a function of cdclk and >> >> ddi clock? Why do we need that? >> >> >> >> drivers/gpu/drm/i915/display/intel_cdclk.c | 15 +++++++-------- >> >> drivers/gpu/drm/i915/display/intel_cdclk.h | 4 ++-- >> >> .../drm/i915/display/intel_display_power_well.c | 4 ++-- >> >> 3 files changed, 11 insertions(+), 12 deletions(-) >> >> >> >> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c >> >> index 26200ee3e23f..caadd880865f 100644 >> >> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c >> >> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c >> >> @@ -2233,17 +2233,16 @@ static bool intel_cdclk_can_squash(struct drm_i915_private *dev_priv, >> >> } >> >> >> >> /** >> >> - * intel_cdclk_needs_modeset - Determine if changong between the CDCLK >> >> - * configurations requires a modeset on all pipes >> >> + * intel_cdclk_params_changed - Check whether CDCLK parameters changed >> >> * @a: first CDCLK configuration >> >> * @b: second CDCLK configuration >> >> * >> >> * Returns: >> >> - * True if changing between the two CDCLK configurations >> >> - * requires all pipes to be off, false if not. >> >> + * True if parameters changed in a way that requires programming the CDCLK >> >> + * and False otherwise. >> >> */ >> >> -bool intel_cdclk_needs_modeset(const struct intel_cdclk_config *a, >> >> - const struct intel_cdclk_config *b) >> >> +bool intel_cdclk_params_changed(const struct intel_cdclk_config *a, >> >> + const struct intel_cdclk_config *b) >> > >> >The new name isn't very descriptive either. >> >> Yeah... I would much rather use intel_cdclk_changed(), but that one is >> already taken. >> >> > >> >Outside the cd2x/crawl/squash cases we stil have to consider >> >two cases: >> >1. cdclk frequency/pll changes (voltage level can change or not) >> >2. cdclk frequency/pll doesn't change, but voltage level needs to change >> > >> >And that difference is what intel_cdclk_needs_modeset() is trying >> >convey. And intel_cdclk_changed() tells us whether anything at all >> >is changing. >> >> I might be missing something, but, by going through the specs, it looked >> to me that voltage level was dependent on cdclk (as well as on ddi >> clock) and not the other way around. That's why I find it odd that we >> need an intel_cdclk_changed() that, besides looking for changes in >> cdclk, also checks for the voltage level. >> >> In intel_set_cdclk(), we check intel_cdclk_changed() before continuing. >> If, for example, there is a change in ddi clock that requires a change >> in voltage level but no changes in cdclk, intel_cdclk_changed() would >> return true, right? Wouldn't that make us unnecessarily go through >> intel_set_cdclk()? > >intel_set_cdclk() is the thing that does the voltage change. Yep and perhaps I provided an incomplete response above. Sorry. I was wondering if handling voltage level should really be intel_set_cdclk()'s responsibility. I might be missing the big picture here, but, at least for the recent platforms, I get the understanding that voltage level handling should be a separate step in the hardware commit process. Would it be possible to have a commit containing (i) update(s) to ddi clk and (ii) no update to cdclk such that (i) require an update to voltage level, right? -- Gustavo Sousa