On Thu, Aug 11, 2016 at 03:54:33PM -0400, Lyude wrote:
> Thanks to Ville for suggesting this as a potential solution to pipe
> underruns on Skylake.
>
> On Skylake all of the registers for configuring planes, including the
> registers for configuring their watermarks, are double buffered. New
> values written to them won't take effect until said registers are
> "armed", which is done by writing to the PLANE_SURF (or in the case of
> cursor planes, the CURBASE register) register.
>
> With this in mind, up until now we've been updating watermarks on skl
> like this:
>
> non-modeset {
> - calculate (during atomic check phase)
> - finish_atomic_commit:
> - intel_pre_plane_update:
> - intel_update_watermarks()
> - {vblank happens; new watermarks + old plane values => underrun }
> - drm_atomic_helper_commit_planes_on_crtc:
> - start vblank evasion
> - write new plane registers
> - end vblank evasion
> }
>
> or
>
> modeset {
> - calculate (during atomic check phase)
> - finish_atomic_commit:
> - crtc_enable:
> - intel_update_watermarks()
> - {vblank happens; new watermarks + old plane values => underrun }
> - drm_atomic_helper_commit_planes_on_crtc:
> - start vblank evasion
> - write new plane registers
> - end vblank evasion
> }
>
> Now we update watermarks atomically like this:
>
> non-modeset {
> - calculate (during atomic check phase)
> - finish_atomic_commit:
> - intel_pre_plane_update:
> - intel_update_watermarks() (wm values aren't written yet)
> - drm_atomic_helper_commit_planes_on_crtc:
> - start vblank evasion
> - write new plane registers
> - write new wm values
> - end vblank evasion
> }
>
> modeset {
> - calculate (during atomic check phase)
> - finish_atomic_commit:
> - crtc_enable:
> - intel_update_watermarks() (actual wm values aren't written
> yet)
> - drm_atomic_helper_commit_planes_on_crtc:
> - start vblank evasion
> - write new plane registers
> - write new wm values
> - end vblank evasion
> }
>
> So this patch moves all of the watermark writes into the right place;
> inside of the vblank evasion where we update all of the registers for
> each plane. While this patch doesn't fix everything, it does allow us to
> update the watermark values in the way the hardware expects us to.
>
> Changes since original patch series:
> - Remove mutex_lock/mutex_unlock since they don't do anything and we're
> not touching global state
> - Move skl_write_cursor_wm/skl_write_plane_wm functions into
> intel_pm.c, make externally visible
> - Add skl_write_plane_wm calls to skl_update_plane
> - Fix conditional for for loop in skl_write_plane_wm (level < max_level
> should be level <= max_level)
> - Make diagram in commit more accurate to what's actually happening
> - Add Fixes:
>
> Changes since v1:
> - Use IS_GEN9() instead of IS_SKYLAKE() since these fixes apply to more
> then just Skylake
> - Update description to make it clear this patch doesn't fix everything
> - Check if pipes were actually changed before writing watermarks
>
> Changes since v2:
> - Write PIPE_WM_LINETIME during vblank evasion
>
> Changes since v3:
> - Rebase against new SAGV patch changes
>
> Changes since v4:
> - Add a parameter to choose what skl_wm_values struct to use when
> writing new plane watermarks
>
> Changes since v5:
> - Remove cursor ddb entry write in skl_write_cursor_wm(), defer until
> patch 6
> - Write WM_LINETIME in intel_begin_crtc_commit()
>
> Changes since v6:
> - Remove redundant dirty_pipes check in skl_write_plane_wm (we check
> this in all places where we call this function, and it was supposed
> to have been removed earlier anyway)
> - In i9xx_update_cursor(), use dev_priv->info.gen >= 9 instead of
> IS_GEN9(dev_priv). We do this everywhere else and I'd imagine this
> needs to be done for gen10 as well
>
> Fixes: 2d41c0b59afc ("drm/i915/skl: SKL Watermark Computation")
> Signed-off-by: Lyude <cpaul@xxxxxxxxxx>
> Reviewed-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> Cc: Radhakrishna Sripada <radhakrishna.sripada@xxxxxxxxx>
> Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_display.c | 17 +++++++++++-
> drivers/gpu/drm/i915/intel_drv.h | 5 ++++
> drivers/gpu/drm/i915/intel_pm.c | 50 ++++++++++++++++++++++++------------
> drivers/gpu/drm/i915/intel_sprite.c | 7 +++++
> 4 files changed, 62 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 35bdd67..b2f8e24 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3386,6 +3386,8 @@ static void skylake_update_primary_plane(struct drm_plane *plane,
> struct drm_i915_private *dev_priv = to_i915(dev);
> struct intel_crtc *intel_crtc = to_intel_crtc(crtc_state->base.crtc);
> struct drm_framebuffer *fb = plane_state->base.fb;
> + struct drm_i915_gem_object *obj = intel_fb_obj(fb);
rebase fail?
Please double check with gcc/sparse that new warnings are kept to a
minimum.
> + struct skl_wm_values *wm = &dev_priv->wm.skl_results;
const?
> int pipe = intel_crtc->pipe;
> u32 plane_ctl;
> unsigned int rotation = plane_state->base.rotation;
> @@ -3419,6 +3421,9 @@ static void skylake_update_primary_plane(struct drm_plane *plane,
> intel_crtc->adjusted_x = src_x;
> intel_crtc->adjusted_y = src_y;
>
> + if (wm->dirty_pipes & drm_crtc_mask(&intel_crtc->base))
> + skl_write_plane_wm(intel_crtc, wm, 0);
Indent fail.
> +
> I915_WRITE(PLANE_CTL(pipe, 0), plane_ctl);
> I915_WRITE(PLANE_OFFSET(pipe, 0), (src_y << 16) | src_x);
> I915_WRITE(PLANE_STRIDE(pipe, 0), stride);
> @@ -10699,9 +10704,13 @@ static void i9xx_update_cursor(struct drm_crtc *crtc, u32 base,
> struct drm_device *dev = crtc->dev;
> struct drm_i915_private *dev_priv = to_i915(dev);
> struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> + struct skl_wm_values *wm = &dev_priv->wm.skl_results;
> int pipe = intel_crtc->pipe;
> uint32_t cntl = 0;
>
> + if (dev_priv->info.gen >= 9 && wm->dirty_pipes & drm_crtc_mask(crtc)
INTEL_GEN()
> + skl_write_cursor_wm(intel_crtc, wm);
> +
> if (plane_state && plane_state->base.visible) {
> cntl = MCURSOR_GAMMA_ENABLE;
> switch (plane_state->base.crtc_w) {
> @@ -14610,10 +14619,12 @@ static void intel_begin_crtc_commit(struct drm_crtc *crtc,
> struct drm_crtc_state *old_crtc_state)
> {
> struct drm_device *dev = crtc->dev;
> + struct drm_i915_private *dev_priv = to_i915(dev);
> struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> struct intel_crtc_state *old_intel_state =
> to_intel_crtc_state(old_crtc_state);
> bool modeset = needs_modeset(crtc->state);
> + enum pipe pipe = intel_crtc->pipe;
>
> /* Perform vblank evasion around commit operation */
> intel_pipe_update_start(intel_crtc);
> @@ -14628,8 +14639,12 @@ static void intel_begin_crtc_commit(struct drm_crtc *crtc,
>
> if (to_intel_crtc_state(crtc->state)->update_pipe)
> intel_update_pipe_config(intel_crtc, old_intel_state);
> - else if (INTEL_INFO(dev)->gen >= 9)
> + else if (INTEL_INFO(dev)->gen >= 9) {
> skl_detach_scalers(intel_crtc);
> +
> + I915_WRITE(PIPE_WM_LINETIME(pipe),
> + dev_priv->wm.skl_hw.wm_linetime[pipe]);
> + }
> }
>
> static void intel_finish_crtc_commit(struct drm_crtc *crtc,
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 76e78b8..88088c3 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1723,6 +1723,11 @@ void skl_ddb_get_hw_state(struct drm_i915_private *dev_priv,
> struct skl_ddb_allocation *ddb /* out */);
> int skl_enable_sagv(struct drm_i915_private *dev_priv);
> int skl_disable_sagv(struct drm_i915_private *dev_priv);
> +void skl_write_cursor_wm(struct intel_crtc *intel_crtc,
> + const struct skl_wm_values *wm);
> +void skl_write_plane_wm(struct intel_crtc *intel_crtc,
> + const struct skl_wm_values *wm,
> + int plane);
> uint32_t ilk_pipe_pixel_rate(const struct intel_crtc_state *pipe_config);
> bool ilk_disable_lp_wm(struct drm_device *dev);
> int sanitize_rc6_option(struct drm_i915_private *dev_priv, int enable_rc6);
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 77166c6..e8653d8 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3779,6 +3779,39 @@ static void skl_ddb_entry_write(struct drm_i915_private *dev_priv,
> I915_WRITE(reg, 0);
> }
>
> +void skl_write_plane_wm(struct intel_crtc *intel_crtc,
> + const struct skl_wm_values *wm,
> + int plane)
> +{
> + struct drm_crtc *crtc = &intel_crtc->base;
> + struct drm_device *dev = crtc->dev;
> + struct drm_i915_private *dev_priv = to_i915(dev);
> + int level, max_level = ilk_wm_max_level(dev);
> + enum pipe pipe = intel_crtc->pipe;
> +
> + for (level = 0; level <= max_level; level++) {
> + I915_WRITE(PLANE_WM(pipe, plane, level),
> + wm->plane[pipe][plane][level]);
> + }
> + I915_WRITE(PLANE_WM_TRANS(pipe, plane), wm->plane_trans[pipe][plane]);
> +}
> +
> +void skl_write_cursor_wm(struct intel_crtc *intel_crtc,
> + const struct skl_wm_values *wm)
> +{
> + struct drm_crtc *crtc = &intel_crtc->base;
> + struct drm_device *dev = crtc->dev;
> + struct drm_i915_private *dev_priv = to_i915(dev);
> + int level, max_level = ilk_wm_max_level(dev);
> + enum pipe pipe = intel_crtc->pipe;
> +
> + for (level = 0; level <= max_level; level++) {
> + I915_WRITE(CUR_WM(pipe, level),
> + wm->plane[pipe][PLANE_CURSOR][level]);
> + }
> + I915_WRITE(CUR_WM_TRANS(pipe), wm->plane_trans[pipe][PLANE_CURSOR]);
> +}
> +
> static void skl_write_wm_values(struct drm_i915_private *dev_priv,
> const struct skl_wm_values *new)
> {
> @@ -3786,7 +3819,7 @@ static void skl_write_wm_values(struct drm_i915_private *dev_priv,
> struct intel_crtc *crtc;
>
> for_each_intel_crtc(dev, crtc) {
> - int i, level, max_level = ilk_wm_max_level(dev);
> + int i;
> enum pipe pipe = crtc->pipe;
>
> if ((new->dirty_pipes & drm_crtc_mask(&crtc->base)) == 0)
> @@ -3794,21 +3827,6 @@ static void skl_write_wm_values(struct drm_i915_private *dev_priv,
> if (!crtc->active)
> continue;
>
> - I915_WRITE(PIPE_WM_LINETIME(pipe), new->wm_linetime[pipe]);
> -
> - for (level = 0; level <= max_level; level++) {
> - for (i = 0; i < intel_num_planes(crtc); i++)
> - I915_WRITE(PLANE_WM(pipe, i, level),
> - new->plane[pipe][i][level]);
> - I915_WRITE(CUR_WM(pipe, level),
> - new->plane[pipe][PLANE_CURSOR][level]);
> - }
> - for (i = 0; i < intel_num_planes(crtc); i++)
> - I915_WRITE(PLANE_WM_TRANS(pipe, i),
> - new->plane_trans[pipe][i]);
> - I915_WRITE(CUR_WM_TRANS(pipe),
> - new->plane_trans[pipe][PLANE_CURSOR]);
> -
> for (i = 0; i < intel_num_planes(crtc); i++) {
> skl_ddb_entry_write(dev_priv,
> PLANE_BUF_CFG(pipe, i),
> diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
> index 366900d..3c560f9 100644
> --- a/drivers/gpu/drm/i915/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/intel_sprite.c
> @@ -203,6 +203,10 @@ skl_update_plane(struct drm_plane *drm_plane,
> struct drm_i915_private *dev_priv = to_i915(dev);
> struct intel_plane *intel_plane = to_intel_plane(drm_plane);
> struct drm_framebuffer *fb = plane_state->base.fb;
> + struct drm_i915_gem_object *obj = intel_fb_obj(fb);
> + struct skl_wm_values *wm = &dev_priv->wm.skl_results;
> + struct drm_crtc *crtc = crtc_state->base.crtc;
> + struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> const int pipe = intel_plane->pipe;
> const int plane = intel_plane->plane + 1;
> u32 plane_ctl;
> @@ -228,6 +232,9 @@ skl_update_plane(struct drm_plane *drm_plane,
>
> plane_ctl |= skl_plane_ctl_rotation(rotation);
>
> + if (wm->dirty_pipes & drm_crtc_mask(crtc))
> + skl_write_plane_wm(intel_crtc, wm, plane);
> +
> if (key->flags) {
> I915_WRITE(PLANE_KEYVAL(pipe, plane), key->min_value);
> I915_WRITE(PLANE_KEYMAX(pipe, plane), key->max_value);
> --
> 2.7.4
--
Ville Syrjälä
Intel OTC
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