Re: [PATCH 02/11] drm/i915: Do not acquire crtc state to check clock during modeset.

Maarten Lankhorst
2015-10-22T13:43:30Z

Op 22-10-15 om 15:08 schreef Daniel Vetter:
> On Thu, Oct 22, 2015 at 01:56:27PM +0200, Maarten Lankhorst wrote:
>> Parallel modesets are still not allowed, but this will allow updating
>> a different crtc during a modeset if the clock is not changed.
>>
>> Additionally when all pipes are DPMS off the cdclk will be lowered
>> to the minimum allowed.
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> ---
>> drivers/gpu/drm/i915/intel_display.c | 90 ++++++++++++++++++++++--------------
>> drivers/gpu/drm/i915/intel_drv.h | 9 ++++
>> 2 files changed, 64 insertions(+), 35 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index 022e628b8520..051a1e2b1c55 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -5237,6 +5237,7 @@ static void modeset_put_power_domains(struct drm_i915_private *dev_priv,
>>
>> static void modeset_update_crtc_power_domains(struct drm_atomic_state *state)
>> {
>> + struct intel_atomic_state *intel_state = to_intel_atomic_state(state);
>> struct drm_device *dev = state->dev;
>> struct drm_i915_private *dev_priv = dev->dev_private;
>> unsigned long put_domains[I915_MAX_PIPES] = {};
>> @@ -5245,13 +5246,20 @@ static void modeset_update_crtc_power_domains(struct drm_atomic_state *state)
>> int i;
>>
>> for_each_crtc_in_state(state, crtc, crtc_state, i) {
>> - if (needs_modeset(crtc->state))
>> - put_domains[to_intel_crtc(crtc)->pipe] =
>> - modeset_get_crtc_power_domains(crtc);
>> + struct intel_crtc *intel_crtc =
>> + to_intel_crtc(crtc);
>> + enum pipe pipe = intel_crtc->pipe;
>> +
>> + if (!needs_modeset(crtc->state))
>> + continue;
>> +
>> + intel_crtc->min_cdclk = intel_state->pipe_cdclk[pipe];
>> +
>> + put_domains[pipe] = modeset_get_crtc_power_domains(crtc);
>> }
>>
>> if (dev_priv->display.modeset_commit_cdclk) {
>> - unsigned int cdclk = to_intel_atomic_state(state)->cdclk;
>> + unsigned int cdclk = intel_state->cdclk;
>>
>> if (cdclk != dev_priv->cdclk_freq &&
>> !WARN_ON(!state->allow_modeset))
>> @@ -5919,7 +5927,6 @@ static int broxton_calc_cdclk(struct drm_i915_private *dev_priv,
>> /*
>> * FIXME:
>> * - remove the guardband, it's not needed on BXT
>> - * - set 19.2MHz bypass frequency if there are no active pipes
>> */
>> if (max_pixclk > 576000*9/10)
>> return 624000;
>> @@ -5929,8 +5936,10 @@ static int broxton_calc_cdclk(struct drm_i915_private *dev_priv,
>> return 384000;
>> else if (max_pixclk > 144000*9/10)
>> return 288000;
>> - else
>> + else if (max_pixclk)
>> return 144000;
>> + else
>> + return 19200;
>> }
>>
>> /* Compute the max pixel clock for new configuration. Uses atomic state if
>> @@ -5939,22 +5948,31 @@ static int intel_mode_max_pixclk(struct drm_device *dev,
>> struct drm_atomic_state *state)
>> {
>> struct intel_crtc *intel_crtc;
>> - struct intel_crtc_state *crtc_state;
>> - int max_pixclk = 0;
>> + int max_pixel_rate = 0;
>> + bool any_active = false;
>>
>> - for_each_intel_crtc(dev, intel_crtc) {
>> - crtc_state = intel_atomic_get_crtc_state(state, intel_crtc);
>> - if (IS_ERR(crtc_state))
>> - return PTR_ERR(crtc_state);
>> + for_each_intel_crtc(state->dev, intel_crtc) {
>> + struct drm_crtc_state *drm_crtc_state;
>> + struct drm_crtc *crtc = &intel_crtc->base;
>> + int pixclk = 0;
>>
>> - if (!crtc_state->base.enable)
>> - continue;
>> + drm_crtc_state = drm_atomic_get_existing_crtc_state(state, crtc);
>> + if (!drm_crtc_state) {
>> + any_active |= intel_crtc->active;
>> + pixclk = intel_crtc->min_cdclk;
>> + } else if (drm_crtc_state->enable) {
>> + struct intel_crtc_state *crtc_state =
>> + to_intel_crtc_state(drm_crtc_state);
>> +
>> + any_active |= drm_crtc_state->active;
>> + pixclk = crtc_state->base.adjusted_mode.crtc_clock;
>> + }
>>
>> - max_pixclk = max(max_pixclk,
>> - crtc_state->base.adjusted_mode.crtc_clock);
>> + to_intel_atomic_state(state)->pipe_cdclk[intel_crtc->pipe] = pixclk;
>> + max_pixel_rate = max(max_pixel_rate, pixclk);
>> }
>>
>> - return max_pixclk;
>> + return any_active ? max_pixel_rate : 0;
>> }
>>
>> static int valleyview_modeset_calc_cdclk(struct drm_atomic_state *state)
>> @@ -9491,29 +9509,35 @@ static void broxton_modeset_commit_cdclk(struct drm_atomic_state *old_state)
>> static int ilk_max_pixel_rate(struct drm_atomic_state *state)
>> {
>> struct intel_crtc *intel_crtc;
>> - struct intel_crtc_state *crtc_state;
>> int max_pixel_rate = 0;
>> + bool any_active = false;
>>
>> for_each_intel_crtc(state->dev, intel_crtc) {
>> - int pixel_rate;
>> -
>> - crtc_state = intel_atomic_get_crtc_state(state, intel_crtc);
>> - if (IS_ERR(crtc_state))
>> - return PTR_ERR(crtc_state);
>> + struct drm_crtc_state *drm_crtc_state;
>> + struct drm_crtc *crtc = &intel_crtc->base;
>> + int pixel_rate = 0;
>>
>> - if (!crtc_state->base.enable)
>> - continue;
>> + drm_crtc_state = drm_atomic_get_existing_crtc_state(state, crtc);
>> + if (!drm_crtc_state) {
>> + any_active |= intel_crtc->active;
>> + pixel_rate = intel_crtc->min_cdclk;
>> + } else if (drm_crtc_state->enable) {
>> + struct intel_crtc_state *crtc_state =
>> + to_intel_crtc_state(drm_crtc_state);
>>
>> - pixel_rate = ilk_pipe_pixel_rate(crtc_state);
>> + any_active |= drm_crtc_state->active;
>> + pixel_rate = ilk_pipe_pixel_rate(crtc_state);
>>
>> - /* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */
>> - if (IS_BROADWELL(state->dev) && crtc_state->ips_enabled)
>> - pixel_rate = DIV_ROUND_UP(pixel_rate * 100, 95);
>> + /* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */
>> + if (IS_BROADWELL(state->dev) && crtc_state->ips_enabled)
>> + pixel_rate = DIV_ROUND_UP(pixel_rate * 100, 95);
>> + }
>>
>> + to_intel_atomic_state(state)->pipe_cdclk[intel_crtc->pipe] = pixel_rate;
>> max_pixel_rate = max(max_pixel_rate, pixel_rate);
>> }
>>
>> - return max_pixel_rate;
>> + return any_active ? max_pixel_rate : 0;
>> }
>>
>> static void broadwell_set_cdclk(struct drm_device *dev, int cdclk)
>> @@ -9612,14 +9636,10 @@ static int broadwell_modeset_calc_cdclk(struct drm_atomic_state *state)
>> else
>> cdclk = 337500;
>>
>> - /*
>> - * FIXME move the cdclk caclulation to
>> - * compute_config() so we can fail gracegully.
>> - */
>> if (cdclk > dev_priv->max_cdclk_freq) {
>> DRM_ERROR("requested cdclk (%d kHz) exceeds max (%d kHz)\n",
>> cdclk, dev_priv->max_cdclk_freq);
>> - cdclk = dev_priv->max_cdclk_freq;
>> + return -EINVAL;
>> }
>>
>> to_intel_atomic_state(state)->cdclk = cdclk;
>> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
>> index 51722e657b91..54a2c0da2ece 100644
>> --- a/drivers/gpu/drm/i915/intel_drv.h
>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -250,6 +250,7 @@ struct intel_atomic_state {
>> unsigned int cdclk;
>> bool dpll_set;
>> struct intel_shared_dpll_config shared_dpll[I915_NUM_PLLS];
>> + unsigned int pipe_cdclk[I915_MAX_PIPES];
>> };
>>
>> struct intel_plane_state {
>> @@ -536,8 +537,16 @@ struct intel_crtc {
>> * Whether the crtc and the connected output pipeline is active. Implies
>> * that crtc->enabled is set, i.e. the current mode configuration has
>> * some outputs connected to this crtc.
>> + *
>> + * Protected by crtc.mutex and connection_mutex
> This needs to be clarified to mean: read-protected by connection_mutex,
> writers additionally must hold crtc->mutex. Same below.
>
> Thinking about this a bit more the usual design we do is put the state
> copies not into the parent object with funky rules, but instead into the
> state of the higher-level objects. So for example the read-only
> plane_active state is in crtc_state->plane_mask.
>
> Similarly in this case here I think it would be cleaner design to have a
> min_cdclk array in intel_state, setting it to 0 if the pipe is totally
> off. That way locking rules are 100% clear: If you need to change it, you
> need to copy the global state and acquire connection_mutex. That
> automatically gives you read-access to all crtc's min_cdclk.
Sorry this is the only case where a dependency on intel_crtc->active is valid.
fbc and watermark users should stop looking at it. (intel_crtc_active)

2 crtc's, #1 requires clock at 100, #2 requires clock at 200.
You do a DPMS mode off on #2, and if you don't track crtc_clock you would set the display clock to 100 and force a modeset on #1 too.
If you immediately do dpms off on #1 afterwards it means that the user would see #1 being disabled, re-enabled and disabled again..

> That way we don't play tricks with get_existing_state, don't add more
> depencies on the legacy-encumbered intel_crtc->active and it's just
> generally more awesome.
The tricks are needed to allow a modeset to run parallel to any page flips.
Though perhaps it would be better to add a struct to dev_priv that contains
min cdclk and a flag to see if the crtc is active or not.

~Maarten