[PATCH 2/2] drm/amd/display: enable idle optimizations for linux (MALL stutter)

[Lakha, Bhawanpreet]

[AMD Public Use]

I would but MALL is not fully validated so it might cause underflow issues if we keep it enabled by default. I can create a feature flag mask if that helps?

Bhawan
________________________________
From: Deucher, Alexander <Alexander.Deucher at amd.com>
Sent: December 17, 2020 12:04 PM
To: Lakha, Bhawanpreet <Bhawanpreet.Lakha at amd.com>; Kazlauskas, Nicholas <Nicholas.Kazlauskas at amd.com>
Cc: amd-gfx at lists.freedesktop.org <amd-gfx at lists.freedesktop.org>
Subject: Re: [PATCH 2/2] drm/amd/display: enable idle optimizations for linux (MALL stutter)


[AMD Public Use]

Can we drop the Kconfig?  With that, the series is:
Acked-by: Alex Deucher <alexander.deucher at amd.com>
________________________________
From: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com>
Sent: Thursday, December 17, 2020 11:54 AM
To: Kazlauskas, Nicholas <Nicholas.Kazlauskas at amd.com>; Deucher, Alexander <Alexander.Deucher at amd.com>
Cc: amd-gfx at lists.freedesktop.org <amd-gfx at lists.freedesktop.org>; Lakha, Bhawanpreet <Bhawanpreet.Lakha at amd.com>; Kazlauskas, Nicholas <Nicholas.Kazlauskas at amd.com>
Subject: [PATCH 2/2] drm/amd/display: enable idle optimizations for linux (MALL stutter)

[Why]
We can only use this feature when the display is idle. When active vblank
irq count is 0 we know all the displays are idle.

[How]
-Add a active vblank irq counter
-Update the counter when we enable/disable vblank irq
-if vblank irq count is 0 we can consider mall stutter

Change-Id: Ib1e14a84ee2e8c6e057072128693449665012584
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com>
Acked-by: Alex Deucher <alexander.deucher at amd.com>
Reviewed-by: Nick Kazlauskas <Nicholas.Kazlauskas at amd.com>
---
 drivers/gpu/drm/amd/display/Kconfig           |  6 +++++
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 22 +++++++++++++++++++
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  9 ++++++++
 drivers/gpu/drm/amd/display/dc/dc.h           |  3 +++
 4 files changed, 40 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig
index 797b5d4b43e5..2444e664c7ee 100644
--- a/drivers/gpu/drm/amd/display/Kconfig
+++ b/drivers/gpu/drm/amd/display/Kconfig
@@ -23,6 +23,12 @@ config DRM_AMD_DC_HDCP
         help
           Choose this option if you want to support HDCP authentication.

+config DRM_AMD_DC_MALL
+       bool "Enable MALL support"
+       depends on DRM_AMD_DC
+       help
+         Choose this option if you want to support MALL
+
 config DRM_AMD_DC_SI
         bool "AMD DC support for Southern Islands ASICs"
         default n
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index a78ec16418b3..080f2a52cfed 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -5479,6 +5479,7 @@ static inline int dm_set_vblank(struct drm_crtc *crtc, bool enable)
         struct amdgpu_crtc *acrtc = to_amdgpu_crtc(crtc);
         struct amdgpu_device *adev = drm_to_adev(crtc->dev);
         struct dm_crtc_state *acrtc_state = to_dm_crtc_state(crtc->state);
+       struct amdgpu_display_manager *dm = &adev->dm;
         int rc = 0;

         if (enable) {
@@ -5494,7 +5495,28 @@ static inline int dm_set_vblank(struct drm_crtc *crtc, bool enable)
                 return rc;

         irq_source = IRQ_TYPE_VBLANK + acrtc->otg_inst;
+#if defined(CONFIG_DRM_AMD_DC_MALL)
+
+       if (!dc_interrupt_set(adev->dm.dc, irq_source, enable))
+               return -EBUSY;
+
+       mutex_lock(&dm->dc_lock);
+
+       if (enable)
+               dm->active_vblank_irq_count++;
+       else
+               dm->active_vblank_irq_count--;
+
+       dc_allow_idle_optimizations(
+               adev->dm.dc, dm->active_vblank_irq_count == 0 ? true : false);
+
+       DRM_DEBUG_DRIVER("Allow idle optimizations (MALL): %d\n", dm->active_vblank_irq_count == 0);
+       mutex_unlock(&dm->dc_lock);
+
+       return 0;
+#else
         return dc_interrupt_set(adev->dm.dc, irq_source, enable) ? 0 : -EBUSY;
+#endif
 }

 static int dm_enable_vblank(struct drm_crtc *crtc)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index 251af783f6b1..cab44bbd2e35 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -336,6 +336,15 @@ struct amdgpu_display_manager {
          */
         const struct gpu_info_soc_bounding_box_v1_0 *soc_bounding_box;

+#if defined(CONFIG_DRM_AMD_DC_MALL)
+       /**
+        * @active_vblank_irq_count
+        *
+        * number of currently active vblank irqs
+        */
+       uint32_t active_vblank_irq_count;
+#endif
+
 #ifdef CONFIG_DEBUG_FS
         /* set the crc calculation window*/
         struct drm_property *crc_win_x_start_property;
diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h
index 33642566bcb2..9d245033eb3d 100644
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -504,6 +504,9 @@ struct dc_debug_options {
         bool dmcub_emulation;
 #if defined(CONFIG_DRM_AMD_DC_DCN)
         bool disable_idle_power_optimizations;
+#endif
+#ifdef CONFIG_DRM_AMD_DC_MALL
+       unsigned int mall_size_override;
 #endif
         bool dmub_command_table; /* for testing only */
         struct dc_bw_validation_profile bw_val_profile;
--
2.25.1

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