Op 24-02-16 om 02:24 schreef Matt Roper:
> On Tue, Feb 23, 2016 at 05:20:13PM -0800, Matt Roper wrote:
>> In addition to calculating final watermarks, let's also pre-calculate a
>> set of intermediate watermark values at atomic check time. These
>> intermediate watermarks are a combination of the watermarks for the old
>> state and the new state; they should satisfy the requirements of both
>> states which means they can be programmed immediately when we commit the
>> atomic state (without waiting for a vblank). Once the vblank does
>> happen, we can then re-program watermarks to the more optimal final
>> value.
>>
>> v2: Significant rebasing/rewriting.
>>
>> v3:
>> - Move 'need_postvbl_update' flag to CRTC state (Daniel)
>> - Don't forget to check intermediate watermark values for validity
>> (Maarten)
>> - Don't due async watermark optimization; just do it at the end of the
>> atomic transaction, after waiting for vblanks. We do want it to be
>> async eventually, but adding that now will cause more trouble for
>> Maarten's in-progress work. (Maarten)
>> - Don't allocate space in crtc_state for intermediate watermarks on
>> platforms that don't need it (gen9+).
>> - Move WaCxSRDisabledForSpriteScaling:ivb into intel_begin_crtc_commit
>> now that ilk_update_wm is gone.
>>
>> v4:
>> - Add a wm_mutex to cover updates to intel_crtc->active and the
>> need_postvbl_update flag. Since we don't have async yet it isn't
>> terribly important yet, but might as well add it now.
>> - Change interface to program watermarks. Platforms will now expose
>> .initial_watermarks() and .optimize_watermarks() functions to do
>> watermark programming. These should lock wm_mutex, copy the
>> appropriate state values into intel_crtc->active, and then call
>> the internal program watermarks function.
>>
>> v5:
>> - Skip intermediate watermark calculation/check during initial hardware
>> readout since we don't trust the existing HW values (and don't have
>> valid values of our own yet).
>> - Don't try to call .optimize_watermarks() on platforms that don't have
>> atomic watermarks yet. (Maarten)
>>
>> v6:
>> - Rebase
>>
>> v7:
>> - Further rebase
>>
>> v8:
>> - A few minor indentation and line length fixes
>>
>> v9:
>> - Yet another rebase since Maarten's patches reworked a bunch of the
>> code (wm_pre, wm_post, etc.) that this was previously based on.
>>
>> v10:
>> - Move wm_mutex to dev_priv to protect against racing commits against
>> disjoint CRTC sets. (Maarten)
>> - Drop unnecessary clearing of cstate->wm.need_postvbl_update (Maarten)
>>
>> v11:
>> - Now that we've moved to atomic watermark updates, make sure we call
>> the proper function to program watermarks in
>> {ironlake,haswell}_crtc_enable(); the failure to do so on the
>> previous patch iteration led to us not actually programming the
>> watermarks before turning on the CRTC, which was the cause of the
>> underruns that the CI system was seeing.
>> - Fix inverted logic for determining when to optimize watermarks. We
>> were needlessly optimizing when the intermediate/optimal values were
>> the same (harmless), but not actually optimizing when they differed
>> (also harmless, but wasteful from a power/bandwidth perspective).
>>
>> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
>> Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
>> ---
> To assist with review, the non-rebasing changes in this iteration vs the
> last one are:
>
>> @@ -4925,7 +4960,7 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
>> */
>> intel_crtc_load_lut(crtc);
>>
>> - intel_update_watermarks(crtc);
>> + dev_priv->display.initial_watermarks(intel_crtc->config);
>> intel_enable_pipe(intel_crtc);
>>
>> if (intel_crtc->config->has_pch_encoder)
>> @@ -5024,7 +5059,7 @@ static void haswell_crtc_enable(struct drm_crtc *crtc)
>> if (!intel_crtc->config->has_dsi_encoder)
>> intel_ddi_enable_transcoder_func(crtc);
>>
>> - intel_update_watermarks(crtc);
>> + dev_priv->display.initial_watermarks(pipe_config);
>> intel_enable_pipe(intel_crtc);
>>
>> if (intel_crtc->config->has_pch_encoder)
Are the intermediate watermarks identical to optimal watermarks during modeset?
> (both new additions to the patch)
>
> and:
>
>> + /*
>> + * If our intermediate WM are identical to the final WM, then we can
>> + * omit the post-vblank programming; only update if it's different.
>> + */
>> + if (memcmp(a, &newstate->wm.optimal.ilk, sizeof(*a)) == 0)
>> + newstate->wm.need_postvbl_update = false;
> (replacement of a "!=" with "==")
Ah, good catch!
Lets just wait for CI before applying again
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