From: José Roberto de Souza Date: Wed, 5 Feb 2020 21:49:45 +0000 (-0800) Subject: drm/i915/dc3co: Add description of how it works X-Git-Tag: baikal/mips/sdk5.9~13997^2~18^2~110 X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=a763e4981844b2bf8b9b18df2f0a04d73161523c;p=kernel.git drm/i915/dc3co: Add description of how it works Add a basic description about how DC3CO works to help people not familiar with it. While at it, I also improved the delayed work handle and function names and removed a debug message that is ambiguous and not much useful, no changes in behavior here. Cc: Anshuman Gupta Cc: Imre Deak Signed-off-by: José Roberto de Souza Reviewed-by: Imre Deak Link: https://patchwork.freedesktop.org/patch/msgid/20200205214945.131012-1-jose.souza@intel.com --- diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c index e86e9dc1fe06f..b4942b6445aee 100644 --- a/drivers/gpu/drm/i915/display/intel_psr.c +++ b/drivers/gpu/drm/i915/display/intel_psr.c @@ -59,6 +59,23 @@ * get called by the frontbuffer tracking code. Note that because of locking * issues the self-refresh re-enable code is done from a work queue, which * must be correctly synchronized/cancelled when shutting down the pipe." + * + * DC3CO (DC3 clock off) + * + * On top of PSR2, GEN12 adds a intermediate power savings state that turns + * clock off automatically during PSR2 idle state. + * The smaller overhead of DC3co entry/exit vs. the overhead of PSR2 deep sleep + * entry/exit allows the HW to enter a low-power state even when page flipping + * periodically (for instance a 30fps video playback scenario). + * + * Every time a flips occurs PSR2 will get out of deep sleep state(if it was), + * so DC3CO is enabled and tgl_dc3co_disable_work is schedule to run after 6 + * frames, if no other flip occurs and the function above is executed, DC3CO is + * disabled and PSR2 is configured to enter deep sleep, resetting again in case + * of another flip. + * Front buffer modifications do not trigger DC3CO activation on purpose as it + * would bring a lot of complexity and most of the moderns systems will only + * use page flips. */ static bool psr_global_enabled(struct drm_i915_private *i915) @@ -583,17 +600,16 @@ static void tgl_psr2_disable_dc3co(struct drm_i915_private *dev_priv) psr2_program_idle_frames(dev_priv, psr_compute_idle_frames(intel_dp)); } -static void tgl_dc5_idle_thread(struct work_struct *work) +static void tgl_dc3co_disable_work(struct work_struct *work) { struct drm_i915_private *dev_priv = - container_of(work, typeof(*dev_priv), psr.idle_work.work); + container_of(work, typeof(*dev_priv), psr.dc3co_work.work); mutex_lock(&dev_priv->psr.lock); /* If delayed work is pending, it is not idle */ - if (delayed_work_pending(&dev_priv->psr.idle_work)) + if (delayed_work_pending(&dev_priv->psr.dc3co_work)) goto unlock; - drm_dbg_kms(&dev_priv->drm, "DC5/6 idle thread\n"); tgl_psr2_disable_dc3co(dev_priv); unlock: mutex_unlock(&dev_priv->psr.lock); @@ -604,7 +620,7 @@ static void tgl_disallow_dc3co_on_psr2_exit(struct drm_i915_private *dev_priv) if (!dev_priv->psr.dc3co_enabled) return; - cancel_delayed_work(&dev_priv->psr.idle_work); + cancel_delayed_work(&dev_priv->psr.dc3co_work); /* Before PSR2 exit disallow dc3co*/ tgl_psr2_disable_dc3co(dev_priv); } @@ -1040,7 +1056,7 @@ void intel_psr_disable(struct intel_dp *intel_dp, mutex_unlock(&dev_priv->psr.lock); cancel_work_sync(&dev_priv->psr.work); - cancel_delayed_work_sync(&dev_priv->psr.idle_work); + cancel_delayed_work_sync(&dev_priv->psr.dc3co_work); } static void psr_force_hw_tracking_exit(struct drm_i915_private *dev_priv) @@ -1350,7 +1366,7 @@ void intel_psr_invalidate(struct drm_i915_private *dev_priv, * When we will be completely rely on PSR2 S/W tracking in future, * intel_psr_flush() will invalidate and flush the PSR for ORIGIN_FLIP * event also therefore tgl_dc3co_flush() require to be changed - * accrodingly in future. + * accordingly in future. */ static void tgl_dc3co_flush(struct drm_i915_private *dev_priv, @@ -1373,7 +1389,7 @@ tgl_dc3co_flush(struct drm_i915_private *dev_priv, goto unlock; tgl_psr2_enable_dc3co(dev_priv); - mod_delayed_work(system_wq, &dev_priv->psr.idle_work, + mod_delayed_work(system_wq, &dev_priv->psr.dc3co_work, dev_priv->psr.dc3co_exit_delay); unlock: @@ -1458,7 +1474,7 @@ void intel_psr_init(struct drm_i915_private *dev_priv) dev_priv->psr.link_standby = dev_priv->vbt.psr.full_link; INIT_WORK(&dev_priv->psr.work, intel_psr_work); - INIT_DELAYED_WORK(&dev_priv->psr.idle_work, tgl_dc5_idle_thread); + INIT_DELAYED_WORK(&dev_priv->psr.dc3co_work, tgl_dc3co_disable_work); mutex_init(&dev_priv->psr.lock); } diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 3452926d7b770..da509d9b8895e 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -504,7 +504,7 @@ struct i915_psr { u16 su_x_granularity; bool dc3co_enabled; u32 dc3co_exit_delay; - struct delayed_work idle_work; + struct delayed_work dc3co_work; bool initially_probed; };