[PATCH] drm/i915/cdclk: Rename intel_cdclk_needs_modeset to intel_cdclk_params_changed

[Gustavo Sousa]

Quoting Ville Syrjälä (2024-02-02 17:06:02-03:00)
>On Fri, Feb 02, 2024 at 09:58:37PM +0200, Ville Syrjälä wrote:
>> 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 at intel.com>
>> > ---
>> > 
>> > 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.
>> 
>> 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.
>
>intel_cdclk_clock_changed() is perhaps the best name I can
>think of, off the top of my head. But I'm notoriously bad at
>naming things so take that with a pinch of salt.

Sounds better indeed. And I think intel_cdclk_changed() would be more
concise, but that one is already taken internally.

--
Gustavo Sousa