On Thu, Feb 20, 2020 at 05:23:47PM +0200, Stanislav Lisovskiy wrote:
> There seems to be a bit of confusing redundancy in a way, how
> plane data rate/min cdclk are calculated.
> In fact both min cdclk, pixel rate and plane data rate are all
> part of the same formula as per BSpec.
>
> However currently we have intel_plane_data_rate, which is used
> to calculate plane data rate and which is also used in bandwidth
> calculations. However for calculating min_cdclk we have another
> piece of code, doing almost same calculation, but a bit differently
> and in a different place. However as both are actually part of same
> formula, probably would be wise to use plane data rate calculations
> as a basis anyway, thus avoiding code duplication and possible bugs
> related to this.
>
> Another thing is that I've noticed that during min_cdclk calculations
> we account for plane scaling, while for plane data rate, we don't.
> crtc->pixel_rate seems to account only for pipe ratio, however it is
> clearly stated in BSpec that plane data rate also need to account
> plane ratio as well.
>
> So what this commit does is:
> - Adds a plane ratio calculation to intel_plane_data_rate
> - Removes redundant calculations from skl_plane_min_cdclk which is
> used for gen9+ and now uses intel_plane_data_rate as a basis from
> there as well.
>
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
> ---
> .../gpu/drm/i915/display/intel_atomic_plane.c | 16 ++++++-
> drivers/gpu/drm/i915/display/intel_sprite.c | 46 +++++++++++--------
> 2 files changed, 41 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> index c86d7a35c816..702dfa14d112 100644
> --- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> +++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> @@ -133,15 +133,27 @@ intel_plane_destroy_state(struct drm_plane *plane,
> kfree(plane_state);
> }
>
> +
> +
> unsigned int intel_plane_data_rate(const struct intel_crtc_state *crtc_state,
> const struct intel_plane_state *plane_state)
> {
> const struct drm_framebuffer *fb = plane_state->hw.fb;
> unsigned int cpp;
> + unsigned int src_w, src_h, dst_w, dst_h;
>
> if (!plane_state->uapi.visible)
> return 0;
>
> + src_w = drm_rect_width(&plane_state->uapi.src) >> 16;
> + src_h = drm_rect_height(&plane_state->uapi.src) >> 16;
> + dst_w = drm_rect_width(&plane_state->uapi.dst);
> + dst_h = drm_rect_height(&plane_state->uapi.dst);
> +
> + /* Downscaling limits the maximum pixel rate */
> + dst_w = min(src_w, dst_w);
> + dst_h = min(src_h, dst_h);
> +
> cpp = fb->format->cpp[0];
>
> /*
> @@ -153,7 +165,9 @@ unsigned int intel_plane_data_rate(const struct intel_crtc_state *crtc_state,
> if (fb->format->is_yuv && fb->format->num_planes > 1)
> cpp *= 4;
>
> - return cpp * crtc_state->pixel_rate;
> + return DIV64_U64_ROUND_UP(mul_u32_u32(cpp * crtc_state->pixel_rate,
> + src_w * src_h),
> + mul_u32_u32(dst_w, dst_h));
You don't need a 64bit divisor for this.
> }
>
> int intel_plane_calc_min_cdclk(struct intel_atomic_state *state,
> diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c b/drivers/gpu/drm/i915/display/intel_sprite.c
> index 7abeefe8dce5..75afb78ff1b0 100644
> --- a/drivers/gpu/drm/i915/display/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/display/intel_sprite.c
> @@ -330,24 +330,34 @@ bool icl_is_hdr_plane(struct drm_i915_private *dev_priv, enum plane_id plane_id)
> }
>
> static void
> -skl_plane_ratio(const struct intel_crtc_state *crtc_state,
> - const struct intel_plane_state *plane_state,
> - unsigned int *num, unsigned int *den)
> +skl_plane_bpp_constraints(const struct intel_crtc_state *crtc_state,
> + const struct intel_plane_state *plane_state,
> + unsigned int *num, unsigned int *den)
> {
> struct drm_i915_private *dev_priv = to_i915(plane_state->uapi.plane->dev);
> const struct drm_framebuffer *fb = plane_state->hw.fb;
> + unsigned int cpp = fb->format->cpp[0];
> +
> + /*
> + * Based on HSD#:1408715493
> + * NV12 cpp == 4, P010 cpp == 8
> + *
> + * FIXME what is the logic behind this?
> + */
> + if (fb->format->is_yuv && fb->format->num_planes > 1)
> + cpp *= 4;
This is ugly. I think we need a plane pixel rate instead of
abusing the data rate as the pixel rate like this.
>
> if (fb->format->cpp[0] == 8) {
> if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv)) {
> *num = 10;
> - *den = 8;
> + *den = 8 * cpp;
> } else {
> *num = 9;
> - *den = 8;
> + *den = 8 * cpp;
> }
> } else {
> *num = 1;
> - *den = 1;
> + *den = cpp;
> }
> }
>
> @@ -355,27 +365,23 @@ static int skl_plane_min_cdclk(const struct intel_crtc_state *crtc_state,
> const struct intel_plane_state *plane_state)
> {
> struct drm_i915_private *dev_priv = to_i915(plane_state->uapi.plane->dev);
> - unsigned int pixel_rate = crtc_state->pixel_rate;
> - unsigned int src_w, src_h, dst_w, dst_h;
> unsigned int num, den;
> + struct intel_plane *plane = to_intel_plane(plane_state->uapi.plane);
>
> - skl_plane_ratio(crtc_state, plane_state, &num, &den);
> + skl_plane_bpp_constraints(crtc_state, plane_state, &num, &den);
>
> /* two pixels per clock on glk+ */
> if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv))
> den *= 2;
>
> - src_w = drm_rect_width(&plane_state->uapi.src) >> 16;
> - src_h = drm_rect_height(&plane_state->uapi.src) >> 16;
> - dst_w = drm_rect_width(&plane_state->uapi.dst);
> - dst_h = drm_rect_height(&plane_state->uapi.dst);
> -
> - /* Downscaling limits the maximum pixel rate */
> - dst_w = min(src_w, dst_w);
> - dst_h = min(src_h, dst_h);
> -
> - return DIV64_U64_ROUND_UP(mul_u32_u32(pixel_rate * num, src_w * src_h),
> - mul_u32_u32(den, dst_w * dst_h));
> + /*
> + * intel_atomic_check_planes has already been called by this
> + * time in intel_atomic_check, so use calculated plane
> + * data rate as a basis, in order not to have duplicate code.
> + * According to BSpec, plane data rate is anyway used as
> + * a basis for this calculation.
> + */
> + return DIV64_U64_ROUND_UP(crtc_state->data_rate[plane->id] * num, den);
> }
>
> static unsigned int
> --
> 2.24.1.485.gad05a3d8e5
--
Ville Syrjälä
Intel
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