On Mon, Sep 18, 2017 at 03:57:38PM +0200, Maarten Lankhorst wrote:
> Op 18-09-17 om 15:32 schreef Vidya Srinivas:
> > From: Uma Shankar <uma.shankar@xxxxxxxxx>
> >
> > For gen9 platforms, dsi timings are driven from port instead of pipe
> > (unlike ddi). Thus, we can't rely on pipe registers to get the timing
> > information. Even scanline register read will not be functional.
> > This is causing vblank evasion logic to fail since it relies on
> > scanline, causing atomic update failure warnings.
> >
> > This patch uses pipe framestamp and current timestamp registers
> > to calculate scanline. This is an indirect way to get the scanline.
> > It helps resolve atomic update failure for gen9 dsi platforms.
> >
> > v2: Addressed Ville and Daniel's review comments. Updated the
> > register MACROs, handled race condition for register reads,
> > extracted timings from the hwmode. Removed the dependency on
> > crtc->config to get the encoder type.
> >
> > v3: Made get scanline function generic
> >
> > Credits-to: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Signed-off-by: Uma Shankar <uma.shankar@xxxxxxxxx>
> > Signed-off-by: Chandra Konduru <chandra.konduru@xxxxxxxxx>
> > Signed-off-by: Vidya Srinivas <vidya.srinivas@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/i915_drv.h | 2 ++
> > drivers/gpu/drm/i915/i915_irq.c | 7 +++++
> > drivers/gpu/drm/i915/i915_reg.h | 11 +++++++
> > drivers/gpu/drm/i915/intel_display.c | 60 ++++++++++++++++++++++++++++++++++++
> > 4 files changed, 80 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > index 1cc31a5..d9efe83 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -4085,6 +4085,8 @@ void intel_sbi_write(struct drm_i915_private *dev_priv, u16 reg, u32 value,
> > u32 vlv_flisdsi_read(struct drm_i915_private *dev_priv, u32 reg);
> > void vlv_flisdsi_write(struct drm_i915_private *dev_priv, u32 reg, u32 val);
> >
> > +u32 gen9_get_scanline(struct intel_crtc *crtc);
> > +
> > /* intel_dpio_phy.c */
> > void bxt_port_to_phy_channel(struct drm_i915_private *dev_priv, enum port port,
> > enum dpio_phy *phy, enum dpio_channel *ch);
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > index 5d391e6..47668dd 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -781,6 +781,7 @@ static int __intel_get_crtc_scanline(struct intel_crtc *crtc)
> > struct drm_vblank_crtc *vblank;
> > enum pipe pipe = crtc->pipe;
> > int position, vtotal;
> > + struct intel_encoder *encoder;
> >
> > if (!crtc->active)
> > return -1;
> > @@ -792,6 +793,12 @@ static int __intel_get_crtc_scanline(struct intel_crtc *crtc)
> > if (mode->flags & DRM_MODE_FLAG_INTERLACE)
> > vtotal /= 2;
> >
> > + if (IS_BROXTON(dev_priv) || IS_GEMINILAKE(dev_priv)) {
> > + for_each_encoder_on_crtc(crtc->base.dev, &crtc->base, encoder)
> > + if (encoder->type == INTEL_OUTPUT_DSI)
> > + return gen9_get_scanline(crtc);
> I really think we shouldn't loop over all encoders for something as critical as __intel_get_crtc_scanline..
> > + }
> > +
> > if (IS_GEN2(dev_priv))
> > position = I915_READ_FW(PIPEDSL(pipe)) & DSL_LINEMASK_GEN2;
> > else
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 0b03260..85168ee 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -8802,6 +8802,17 @@ enum skl_power_gate {
> > #define MIPIO_TXESC_CLK_DIV2 _MMIO(0x160008)
> > #define GLK_TX_ESC_CLK_DIV2_MASK 0x3FF
> >
> > +/* Gen4+ Timestamp and Pipe Frame time stamp registers */
> > +#define GEN4_TIMESTAMP_CTR _MMIO(MCHBAR_MIRROR_BASE + 0x2358)
> > +#define GEN7_TIMESTAMP_CTR _MMIO(0x44070)
> > +
> > +#define _PIPE_FRMTMSTMP_A 0x70048
> > +#define _PIPE_FRMTMSTMP_B 0x71048
> > +#define _IVB_PIPE_FRMTMSTMP_C 0x72048
> > +#define PIPE_FRMTMSTMP(pipe) \
> > + _MMIO_PIPE3((pipe), _PIPE_FRMTMSTMP_A, \
> > + _PIPE_FRMTMSTMP_B, _IVB_PIPE_FRMTMSTMP_C)
> > +
> > /* BXT MIPI clock controls */
> > #define BXT_MAX_VAR_OUTPUT_KHZ 39500
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 0871807..601032f 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -10352,6 +10352,66 @@ static bool needs_scaling(const struct intel_plane_state *state)
> > return (src_w != dst_w || src_h != dst_h);
> > }
> >
> > +/*
> > + * For Gen9 DSI, pipe scanline register will not
> > + * work to get the scanline since the timings
> > + * are driven from the PORT (unlike DDI encoders).
> > + * This function will use Framestamp and current
> > + * timestamp registers to calculate the scanline.
> > + */
> > +u32 gen9_get_scanline(struct intel_crtc *crtc)
> > +{
> > + struct drm_device *dev = crtc->base.dev;
> > + struct drm_i915_private *dev_priv = to_i915(dev);
> > + u32 crtc_vblank_start = crtc->base.mode.crtc_vblank_start;
> > + u32 crtc_vtotal = crtc->base.mode.crtc_vtotal;
> > + u32 crtc_htotal = crtc->base.mode.crtc_htotal;
> > + u32 crtc_clock = crtc->base.mode.crtc_clock;
> > + u64 scanline = 0, scan_prev_time, scan_curr_time, scan_post_time;
> Aren't all those 0 since they're only set for crtc_state->adjusted_mode, while crtc->mode is assigned to crtc_state->mode? You'd probably need to look at dev->vblank[crtc->pipe].hwmode for those, which should have been passed as parameter..
> With a bit of luck you could even use the derived ns values set in drm_calc_timestamping_constants, so you don't have to do the math here yourself.
IIRC the derived values ended up having quite a bit of rounding error
in them. Or maybe that just the pixel duration (which IIRC I nuked
already). I would have nuked the line duration too if it wasn't for
nouveau using it. So I think I'd rather not expand its use.
Not sure we'd actually save anything by using the derived value anyway.
We'll still have to do the expensive division at least. Hmm. I guess we
could get rid of one multiplication.
> > + WARN_ON(!crtc_vtotal);
> > + if (!crtc_vtotal)
> > + return scanline;
> > +
> > + /* To avoid the race condition where we might cross into the
> > + * next vblank just between the PIPE_FRMTMSTMP and TIMESTAMP_CTR
> > + * reads. We make sure we read PIPE_FRMTMSTMP and TIMESTAMP_CTR
> > + * during the same frame.
> > + */
> > + do {
> > + /*
> > + * This field provides read back of the display
> > + * pipe frame time stamp. The time stamp value
> > + * is sampled at every start of vertical blank.
> > + */
> > + scan_prev_time = I915_READ_FW(PIPE_FRMTMSTMP(crtc->pipe));
> > +
> > + /*
> > + * The TIMESTAMP_CTR register has the current
> > + * time stamp value.
> > + */
> > + scan_curr_time = I915_READ_FW(GEN7_TIMESTAMP_CTR);
> > +
> > + scan_post_time = I915_READ_FW(PIPE_FRMTMSTMP(crtc->pipe));
> > + } while (scan_post_time != scan_prev_time);
> > +
> > + /*
> > + * Since the register is 32 bit and the values
> > + * can overflow and wrap around, making sure
> > + * current time accounts for the register
> > + * wrap
> > + */
> > + if (scan_curr_time < scan_prev_time)
> > + scan_curr_time += 0x100000000;
> > +
> > + scanline = div_u64(mul_u64_u32_shr((scan_curr_time - scan_prev_time),
> Isn't mul_u64_u32_div exactly what you want here?
I think we'd actually want a mul_u32_u32_div(). But that doesn't seem
to exist.
> > + crtc_clock, 0), 1000 * crtc_htotal);
> > + scanline = min(scanline, (u64)(crtc_vtotal - 1));
> > + scanline = (scanline + crtc_vblank_start) % crtc_vtotal;
> > +
> > + return scanline;
> > +}
> > +
> > int intel_plane_atomic_calc_changes(const struct intel_crtc_state *old_crtc_state,
> > struct drm_crtc_state *crtc_state,
> > const struct intel_plane_state *old_plane_state,
>
>
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--
Ville Syrjälä
Intel OTC
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