Re: [Freedreno] [v4] drm/msm/disp/dpu1: turn off vblank irqs aggressively in dpu driver

[kalyan_t@xxxxxxxxxxxxxx]

On 2021-02-22 21:38, Rob Clark wrote:
> On Thu, Feb 18, 2021 at 4:36 AM Kalyan Thota <kalyan_t@xxxxxxxxxxxxxx> 
> wrote:
> > Set the flag vblank_disable_immediate = true to turn off vblank irqs
> > immediately as soon as drm_vblank_put is requested so that there are
> > no irqs triggered during idle state. This will reduce cpu wakeups
> > and help in power saving.
> >
> > To enable vblank_disable_immediate flag the underlying KMS driver
> > needs to support high precision vblank timestamping and also a
> > reliable way of providing vblank counter which is incrementing
> > at the leading edge of vblank.
> >
> > This patch also brings in changes to support vblank_disable_immediate
> > requirement in dpu driver.
> >
> > Changes in v1:
> >  - Specify reason to add vblank timestamp support. (Rob).
> >  - Add changes to provide vblank counter from dpu driver.
> >
> > Changes in v2:
> >  - Fix warn stack reported by Rob Clark with v2 patch.
> >
> > Changes in v3:
> >  - Move back to HW frame counter (Rob).
>
> could you let me know what the delta was in v4?  (No need to resend
> yet, if needed I can amend the commit msg when applying)
    - Frame count mismatch was causing a DRM WARN stack spew.
      DPU HW will increment the frame count at the end of
      the sync, where as vblank will be triggered at the
      fetch_start counter which is calculated as v_total - vfp.
      This is to start fetching early for panels with low
      vbp w.r.t hw latency lines.

      Add logic to detect the line count if it falls between
      vactive and v_total then return incremented frame count value.
> BR,
> -R
>
> >  Signed-off-by: Kalyan Thota <kalyan_t@xxxxxxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c           | 80 
> > ++++++++++++++++++++++
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c        | 30 ++++++++
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h        | 11 +++
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h   |  1 +
> >  .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c   | 26 +++++++
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c        |  1 +
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h        |  1 +
> >  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c            |  5 ++
> >  8 files changed, 155 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > index d4662e8..9a80981 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > @@ -65,6 +65,83 @@ static void dpu_crtc_destroy(struct drm_crtc *crtc)
> >         kfree(dpu_crtc);
> >  }
> >
> > +static struct drm_encoder *get_encoder_from_crtc(struct drm_crtc 
> > *crtc)
> > +{
> > +       struct drm_device *dev = crtc->dev;
> > +       struct drm_encoder *encoder;
> > +
> > +       drm_for_each_encoder(encoder, dev)
> > +               if (encoder->crtc == crtc)
> > +                       return encoder;
> > +
> > +       return NULL;
> > +}
> > +
> > +static u32 dpu_crtc_get_vblank_counter(struct drm_crtc *crtc)
> > +{
> > +       struct drm_encoder *encoder;
> > +
> > +       encoder = get_encoder_from_crtc(crtc);
> > +       if (!encoder) {
> > +               DRM_ERROR("no encoder found for crtc %d\n", 
> > crtc->index);
> > +               return false;
> > +       }
> > +
> > +       return dpu_encoder_get_frame_count(encoder);
> > +}
> > +
> > +static bool dpu_crtc_get_scanout_position(struct drm_crtc *crtc,
> > +                                          bool in_vblank_irq,
> > +                                          int *vpos, int *hpos,
> > +                                          ktime_t *stime, ktime_t 
> > *etime,
> > +                                          const struct 
> > drm_display_mode *mode)
> > +{
> > +       unsigned int pipe = crtc->index;
> > +       struct drm_encoder *encoder;
> > +       int line, vsw, vbp, vactive_start, vactive_end, vfp_end;
> > +
> > +       encoder = get_encoder_from_crtc(crtc);
> > +       if (!encoder) {
> > +               DRM_ERROR("no encoder found for crtc %d\n", pipe);
> > +               return false;
> > +       }
> > +
> > +       vsw = mode->crtc_vsync_end - mode->crtc_vsync_start;
> > +       vbp = mode->crtc_vtotal - mode->crtc_vsync_end;
> > +
> > +       /*
> > +        * the line counter is 1 at the start of the VSYNC pulse and 
> > VTOTAL at
> > +        * the end of VFP. Translate the porch values relative to the 
> > line
> > +        * counter positions.
> > +        */
> > +
> > +       vactive_start = vsw + vbp + 1;
> > +       vactive_end = vactive_start + mode->crtc_vdisplay;
> > +
> > +       /* last scan line before VSYNC */
> > +       vfp_end = mode->crtc_vtotal;
> > +
> > +       if (stime)
> > +               *stime = ktime_get();
> > +
> > +       line = dpu_encoder_get_linecount(encoder);
> > +
> > +       if (line < vactive_start)
> > +               line -= vactive_start;
> > +       else if (line > vactive_end)
> > +               line = line - vfp_end - vactive_start;
> > +       else
> > +               line -= vactive_start;
> > +
> > +       *vpos = line;
> > +       *hpos = 0;
> > +
> > +       if (etime)
> > +               *etime = ktime_get();
> > +
> > +       return true;
> > +}
> > +
> >  static void _dpu_crtc_setup_blend_cfg(struct dpu_crtc_mixer *mixer,
> >                 struct dpu_plane_state *pstate, struct dpu_format 
> > *format)
> >  {
> > @@ -1243,6 +1320,8 @@ static const struct drm_crtc_funcs 
> > dpu_crtc_funcs = {
> >         .early_unregister = dpu_crtc_early_unregister,
> >         .enable_vblank  = msm_crtc_enable_vblank,
> >         .disable_vblank = msm_crtc_disable_vblank,
> > +       .get_vblank_timestamp = 
> > drm_crtc_vblank_helper_get_vblank_timestamp,
> > +       .get_vblank_counter = dpu_crtc_get_vblank_counter,
> >  };
> >
> >  static const struct drm_crtc_helper_funcs dpu_crtc_helper_funcs = {
> > @@ -1251,6 +1330,7 @@ static const struct drm_crtc_helper_funcs 
> > dpu_crtc_helper_funcs = {
> >         .atomic_check = dpu_crtc_atomic_check,
> >         .atomic_begin = dpu_crtc_atomic_begin,
> >         .atomic_flush = dpu_crtc_atomic_flush,
> > +       .get_scanout_position = dpu_crtc_get_scanout_position,
> >  };
> >
> >  /* initialize crtc */
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > index f7f5c25..5cd3f31 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > @@ -425,6 +425,36 @@ int dpu_encoder_helper_unregister_irq(struct 
> > dpu_encoder_phys *phys_enc,
> >         return 0;
> >  }
> >
> > +int dpu_encoder_get_frame_count(struct drm_encoder *drm_enc)
> > +{
> > +       struct dpu_encoder_virt *dpu_enc;
> > +       struct dpu_encoder_phys *phys;
> > +       int framecount = 0;
> > +
> > +       dpu_enc = to_dpu_encoder_virt(drm_enc);
> > +       phys = dpu_enc ? dpu_enc->cur_master : NULL;
> > +
> > +       if (phys && phys->ops.get_frame_count)
> > +               framecount = phys->ops.get_frame_count(phys);
> > +
> > +       return framecount;
> > +}
> > +
> > +int dpu_encoder_get_linecount(struct drm_encoder *drm_enc)
> > +{
> > +       struct dpu_encoder_virt *dpu_enc;
> > +       struct dpu_encoder_phys *phys;
> > +       int linecount = 0;
> > +
> > +       dpu_enc = to_dpu_encoder_virt(drm_enc);
> > +       phys = dpu_enc ? dpu_enc->cur_master : NULL;
> > +
> > +       if (phys && phys->ops.get_line_count)
> > +               linecount = phys->ops.get_line_count(phys);
> > +
> > +       return linecount;
> > +}
> > +
> >  void dpu_encoder_get_hw_resources(struct drm_encoder *drm_enc,
> >                                   struct dpu_encoder_hw_resources 
> > *hw_res)
> >  {
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > index b491346..99a5d73 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> > @@ -156,5 +156,16 @@ void dpu_encoder_prepare_commit(struct 
> > drm_encoder *drm_enc);
> >   */
> >  void dpu_encoder_set_idle_timeout(struct drm_encoder *drm_enc,
> >                                                         u32 
> > idle_timeout);
> > +/**
> > + * dpu_encoder_get_linecount - get interface line count for the 
> > encoder.
> > + * @drm_enc:    Pointer to previously created drm encoder structure
> > + */
> > +int dpu_encoder_get_linecount(struct drm_encoder *drm_enc);
> > +
> > +/**
> > + * dpu_encoder_get_frame_count - get interface frame count for the 
> > encoder.
> > + * @drm_enc:    Pointer to previously created drm encoder structure
> > + */
> > +int dpu_encoder_get_frame_count(struct drm_encoder *drm_enc);
> >
> >  #endif /* __DPU_ENCODER_H__ */
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
> > index f8f2515..ecbc4be 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
> > @@ -143,6 +143,7 @@ struct dpu_encoder_phys_ops {
> >         void (*prepare_idle_pc)(struct dpu_encoder_phys *phys_enc);
> >         void (*restore)(struct dpu_encoder_phys *phys);
> >         int (*get_line_count)(struct dpu_encoder_phys *phys);
> > +       int (*get_frame_count)(struct dpu_encoder_phys *phys);
> >  };
> >
> >  /**
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> > index 9a69fad..0e06b7e 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
> > @@ -658,6 +658,31 @@ static int dpu_encoder_phys_vid_get_line_count(
> >         return 
> > phys_enc->hw_intf->ops.get_line_count(phys_enc->hw_intf);
> >  }
> >
> > +static int dpu_encoder_phys_vid_get_frame_count(
> > +               struct dpu_encoder_phys *phys_enc)
> > +{
> > +       struct intf_status s = {0};
> > +       u32 fetch_start = 0;
> > +       struct drm_display_mode mode = phys_enc->cached_mode;
> > +
> > +       if (!dpu_encoder_phys_vid_is_master(phys_enc))
> > +               return -EINVAL;
> > +
> > +       if (!phys_enc->hw_intf || !phys_enc->hw_intf->ops.get_status)
> > +               return -EINVAL;
> > +
> > +       phys_enc->hw_intf->ops.get_status(phys_enc->hw_intf, &s);
> > +
> > +       if (s.is_prog_fetch_en && s.is_en) {
> > +               fetch_start = mode.vtotal - (mode.vsync_start - 
> > mode.vdisplay);
> > +               if ((s.line_count > fetch_start) &&
> > +                       (s.line_count <= mode.vtotal))
> > +                       return s.frame_count + 1;
> > +       }
> > +
> > +       return s.frame_count;
> > +}
> > +
> >  static void dpu_encoder_phys_vid_init_ops(struct dpu_encoder_phys_ops 
> > *ops)
> >  {
> >         ops->is_master = dpu_encoder_phys_vid_is_master;
> > @@ -676,6 +701,7 @@ static void dpu_encoder_phys_vid_init_ops(struct 
> > dpu_encoder_phys_ops *ops)
> >         ops->handle_post_kickoff = 
> > dpu_encoder_phys_vid_handle_post_kickoff;
> >         ops->needs_single_flush = 
> > dpu_encoder_phys_vid_needs_single_flush;
> >         ops->get_line_count = dpu_encoder_phys_vid_get_line_count;
> > +       ops->get_frame_count = dpu_encoder_phys_vid_get_frame_count;
> >  }
> >
> >  struct dpu_encoder_phys *dpu_encoder_phys_vid_init(
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> > index 6f0f545..717178b 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
> > @@ -256,6 +256,7 @@ static void dpu_hw_intf_get_status(
> >         struct dpu_hw_blk_reg_map *c = &intf->hw;
> >
> >         s->is_en = DPU_REG_READ(c, INTF_TIMING_ENGINE_EN);
> > +       s->is_prog_fetch_en = !!(DPU_REG_READ(c, INTF_CONFIG) & 
> > BIT(31));
> >         if (s->is_en) {
> >                 s->frame_count = DPU_REG_READ(c, INTF_FRAME_COUNT);
> >                 s->line_count = DPU_REG_READ(c, INTF_LINE_COUNT);
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
> > index 0ead64d..3568be8 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
> > @@ -40,6 +40,7 @@ struct intf_prog_fetch {
> >
> >  struct intf_status {
> >         u8 is_en;               /* interface timing engine is enabled 
> > or not */
> > +       u8 is_prog_fetch_en;    /* interface prog fetch counter is 
> > enabled or not */
> >         u32 frame_count;        /* frame count since timing engine 
> > enabled */
> >         u32 line_count;         /* current line count including 
> > blanking */
> >  };
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c 
> > b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > index 374b0e8..ed636f1 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > @@ -14,6 +14,7 @@
> >
> >  #include <drm/drm_crtc.h>
> >  #include <drm/drm_file.h>
> > +#include <drm/drm_vblank.h>
> >
> >  #include "msm_drv.h"
> >  #include "msm_mmu.h"
> > @@ -1020,6 +1021,10 @@ static int dpu_kms_hw_init(struct msm_kms *kms)
> >          */
> >         dev->mode_config.allow_fb_modifiers = true;
> >
> > +       dev->max_vblank_count = 0xffffffff;
> > +       /* Disable vblank irqs aggressively for power-saving */
> > +       dev->vblank_disable_immediate = true;
> > +
> >         /*
> >          * _dpu_kms_drm_obj_init should create the DRM related objects
> >          * i.e. CRTCs, planes, encoders, connectors and so forth
> > --
> > 2.7.4
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