Re: [PATCH 5/6] drm/i915: Make updating pipe without modeset atomic.

Daniel Vetter
2015-07-21T14:47:37Z

On Tue, Jul 21, 2015 at 04:32:26PM +0200, Maarten Lankhorst wrote:
> Op 21-07-15 om 16:14 schreef Daniel Vetter:
> > On Tue, Jul 21, 2015 at 01:29:01PM +0200, Maarten Lankhorst wrote:
> >> Instead of doing a hack during primary plane commit the state
> >> is updated during atomic evasion. It handles differences in
> >> pipe size and the panel fitter.
> >>
> >> This is continuing on top of Daniel's work to make faster
> >> modesets atomic, and not yet enabled by default.
> >>
> >> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> >> ---
> >> drivers/gpu/drm/i915/intel_atomic.c | 2 +-
> >> drivers/gpu/drm/i915/intel_display.c | 93 ++++++++++++++++++++----------------
> >> drivers/gpu/drm/i915/intel_drv.h | 2 +
> >> 3 files changed, 55 insertions(+), 42 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/intel_atomic.c b/drivers/gpu/drm/i915/intel_atomic.c
> >> index 09a0ad611002..58d62fbe961b 100644
> >> --- a/drivers/gpu/drm/i915/intel_atomic.c
> >> +++ b/drivers/gpu/drm/i915/intel_atomic.c
> >> @@ -98,8 +98,8 @@ intel_crtc_duplicate_state(struct drm_crtc *crtc)
> >> return NULL;
> >>
> >> __drm_atomic_helper_crtc_duplicate_state(crtc, &crtc_state->base);
> >> -
> >> crtc_state->base.crtc = crtc;
> >> + crtc_state->update_pipe = false;
> >>
> >> return &crtc_state->base;
> >> }
> >> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> >> index 443328033981..480b2336c7ba 100644
> >> --- a/drivers/gpu/drm/i915/intel_display.c
> >> +++ b/drivers/gpu/drm/i915/intel_display.c
> >> @@ -108,6 +108,9 @@ static void skl_init_scalers(struct drm_device *dev, struct intel_crtc *intel_cr
> >> struct intel_crtc_state *crtc_state);
> >> static int i9xx_get_refclk(const struct intel_crtc_state *crtc_state,
> >> int num_connectors);
> >> +static void skylake_pfit_enable(struct intel_crtc *crtc);
> >> +static void ironlake_pfit_disable(struct intel_crtc *crtc, bool force);
> >> +static void ironlake_pfit_enable(struct intel_crtc *crtc);
> >> static void intel_modeset_setup_hw_state(struct drm_device *dev);
> >>
> >> typedef struct {
> >> @@ -3268,14 +3271,17 @@ static bool intel_crtc_has_pending_flip(struct drm_crtc *crtc)
> >> return pending;
> >> }
> >>
> >> -static void intel_update_pipe_size(struct intel_crtc *crtc)
> >> +static void intel_update_pipe_config(struct intel_crtc *crtc,
> >> + struct intel_crtc_state *old_crtc_state)
> > upate_pipe_config sounds like it's just updating the hw state. Maybe call
> > it intel_fastset_crtc or intel_fixup_crtc or just intel_update_crtc? The
> > other functions are also called crtc_enable/disable, so going with crtc
> > seems more consistent.
> intel_crtc_update_pipe ?
>
> >> {
> >> struct drm_device *dev = crtc->base.dev;
> >> struct drm_i915_private *dev_priv = dev->dev_private;
> >> - const struct drm_display_mode *adjusted_mode;
> >> + struct intel_crtc_state *pipe_config =
> >> + to_intel_crtc_state(crtc->base.state);
> >>
> >> - if (!i915.fastboot)
> >> - return;
> >> + DRM_DEBUG_KMS("Updating pipe size %ix%i -> %ix%i\n",
> >> + old_crtc_state->pipe_src_w, old_crtc_state->pipe_src_h,
> >> + pipe_config->pipe_src_w, pipe_config->pipe_src_h);
> >>
> >> if (HAS_DDI(dev))
> >> intel_set_pipe_csc(&crtc->base);
> >> @@ -3287,27 +3293,26 @@ static void intel_update_pipe_size(struct intel_crtc *crtc)
> >> * fastboot case, we'll flip, but if we don't update the pipesrc and
> >> * pfit state, we'll end up with a big fb scanned out into the wrong
> >> * sized surface.
> >> - *
> >> - * To fix this properly, we need to hoist the checks up into
> >> - * compute_mode_changes (or above), check the actual pfit state and
> >> - * whether the platform allows pfit disable with pipe active, and only
> >> - * then update the pipesrc and pfit state, even on the flip path.
> >> */
> >>
> >> - adjusted_mode = &crtc->config->base.adjusted_mode;
> >> -
> >> I915_WRITE(PIPESRC(crtc->pipe),
> >> - ((adjusted_mode->crtc_hdisplay - 1) << 16) |
> >> - (adjusted_mode->crtc_vdisplay - 1));
> >> - if (!crtc->config->pch_pfit.enabled &&
> >> - (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS) ||
> >> - intel_pipe_has_type(crtc, INTEL_OUTPUT_EDP))) {
> >> - I915_WRITE(PF_CTL(crtc->pipe), 0);
> >> - I915_WRITE(PF_WIN_POS(crtc->pipe), 0);
> >> - I915_WRITE(PF_WIN_SZ(crtc->pipe), 0);
> >> + ((pipe_config->pipe_src_w - 1) << 16) |
> >> + (pipe_config->pipe_src_h - 1));
> >> +
> >> + /* on skylake this is done by detaching scalers */
> >> + if (INTEL_INFO(dev)->gen == 9) {
> >> + skl_detach_scalers(crtc);
> >> +
> >> + if (pipe_config->pch_pfit.enabled)
> >> + skylake_pfit_enable(crtc);
> >> + }
> >> + else if (INTEL_INFO(dev)->gen < 9 &&
> >> + HAS_PCH_SPLIT(dev)) {
> >> + if (pipe_config->pch_pfit.enabled)
> >> + ironlake_pfit_enable(crtc);
> >> + else if (old_crtc_state->pch_pfit.enabled)
> >> + ironlake_pfit_disable(crtc, true);
> > Iirc Jesse's experiments showed that you could only disable the pfit
> > without a modeset, but not enable it without a modeset. Not sure how that
> > works on skl, but that's what I remember for ealier platforms at least.
> Is that really the case, or because of the power domain updates? Which, come to think of it, I don't
> handle correctly in this patch. :/
>
> intel_ddi_enable_transcoder_func seems to have a special case for haswell on eDP with panel fitter on/off.
> So perhaps disallow off -> on with haswell.
>
> Broadwell might not be able to change panel fitter from on to off, because of cdclk calculations:
> broadwell_modeset_calc_cdclk -> ilk_max_pixel_rate -> ilk_pipe_pixel_rate
>
> Those reasons might be contributing to failures.
>
> > Also it should work the same for gmch platforms really.
> Probably, but I wasn't able to test it and current code didn't seem to handle it.
>
> > Also big thing still missing is the special testcase which does direct
> > modesets trying to force fastset pfit changes on edp/dsi/lvds.
> Indeed! What should I expect on failure, and how do I define success?

One part is just exercising the code, i.e. do various modesets from
different modes to other modes to cover all the cases:
- off->on
- on->off
- on->on but chaning upscaling.

That would be really good already. Bonus points if you bother with an
atomic version which checks that it's indeed done in one vblank (using
timestamps and clearing the ALLOW_MODESET flag). But imo that's overkill.
Most of the correctness prove should be possible by catching pipe
underruns when we screw it up somehow.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation