On Tue, Feb 25, 2020 at 12:35:45PM +0530, Pankaj Bharadiya wrote:
> Integer scaling (IS) is a nearest-neighbor upscaling technique that
> simply scales up the existing pixels by an integer
> (i.e., whole number) multiplier.Nearest-neighbor (NN) interpolation
> works by filling in the missing color values in the upscaled image
> with that of the coordinate-mapped nearest source pixel value.
>
> Both IS and NN preserve the clarity of the original image. Integer
> scaling is particularly useful for pixel art games that rely on
> sharp, blocky images to deliver their distinctive look.
>
> Program the scaler filter coefficients to enable the NN filter if
> scaling filter property is set to DRM_SCALING_FILTER_NEAREST_NEIGHBOR
> and enable integer scaling.
>
> Bspec: 49247
>
> Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@xxxxxxxxx>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_display.c | 83 +++++++++++++++++++-
> drivers/gpu/drm/i915/display/intel_display.h | 2 +
> drivers/gpu/drm/i915/display/intel_sprite.c | 20 +++--
> 3 files changed, 97 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index b5903ef3c5a0..6d5f59203258 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -6237,6 +6237,73 @@ void skl_scaler_disable(const struct intel_crtc_state *old_crtc_state)
> skl_detach_scaler(crtc, i);
> }
>
> +/**
> + * Theory behind setting nearest-neighbor integer scaling:
> + *
> + * 17 phase of 7 taps requires 119 coefficients in 60 dwords per set.
> + * The letter represents the filter tap (D is the center tap) and the number
> + * represents the coefficient set for a phase (0-16).
> + *
> + * +------------+------------------------+------------------------+
> + * |Index value | Data value coeffient 1 | Data value coeffient 2 |
> + * +------------+------------------------+------------------------+
> + * | 00h | B0 | A0 |
> + * +------------+------------------------+------------------------+
> + * | 01h | D0 | C0 |
> + * +------------+------------------------+------------------------+
> + * | 02h | F0 | E0 |
> + * +------------+------------------------+------------------------+
> + * | 03h | A1 | G0 |
> + * +------------+------------------------+------------------------+
> + * | 04h | C1 | B1 |
> + * +------------+------------------------+------------------------+
> + * | ... | ... | ... |
> + * +------------+------------------------+------------------------+
> + * | 38h | B16 | A16 |
> + * +------------+------------------------+------------------------+
> + * | 39h | D16 | C16 |
> + * +------------+------------------------+------------------------+
> + * | 3Ah | F16 | C16 |
> + * +------------+------------------------+------------------------+
> + * | 3Bh | Reserved | G16 |
> + * +------------+------------------------+------------------------+
> + *
> + * To enable nearest-neighbor scaling: program scaler coefficents with
> + * the center tap (Dxx) values set to 1 and all other values set to 0 as per
> + * SCALER_COEFFICIENT_FORMAT
> + *
> + */
> +void skl_setup_nearest_neighbor_filter(struct drm_i915_private *dev_priv,
> + enum pipe pipe, int scaler_id)
skl_scaler_...
> +{
> +
> + int coeff = 0;
> + int phase = 0;
> + int tap;
> + int val = 0;
Needlessly wide scope for most of these.
> +
> + /*enable the index auto increment.*/
> + intel_de_write_fw(dev_priv, SKL_PS_COEF_INDEX_SET0(pipe, scaler_id),
> + _PS_COEE_INDEX_AUTO_INC);
> +
> + for (phase = 0; phase < 17; phase++) {
> + for (tap = 0; tap < 7; tap++) {
> + coeff++;
Can be part of the % check.
> + if (tap == 3)
> + val = (phase % 2) ? (0x800) : (0x800 << 16);
Parens overload.
> +
> + if (coeff % 2 == 0) {
> + intel_de_write_fw(dev_priv, SKL_PS_COEF_DATA_SET0(pipe, scaler_id), val);
> + val = 0;
Can drop this val=0 if you move the variable into tight scope and
initialize there.
I was trying to think of a bit more generic way to do this, but couldn't
really think of anything apart from pre-filling the entire coefficient
set and the programming blindly. And that seems a bit wasteful if we only
care about nearest neighbour.
> + }
> +
> + }
> +
> + }
> +
> + intel_de_write_fw(dev_priv, SKL_PS_COEF_DATA_SET0(pipe, scaler_id), 0);
> +}
> +
> static void skl_pfit_enable(const struct intel_crtc_state *crtc_state)
> {
> struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> @@ -6260,9 +6327,23 @@ static void skl_pfit_enable(const struct intel_crtc_state *crtc_state)
> pfit_w = (crtc_state->pch_pfit.size >> 16) & 0xFFFF;
> pfit_h = crtc_state->pch_pfit.size & 0xFFFF;
>
> + id = scaler_state->scaler_id;
> +
> if (state->scaling_filter ==
> DRM_SCALING_FILTER_NEAREST_NEIGHBOR) {
> scaling_filter = PS_FILTER_PROGRAMMED;
> + skl_setup_nearest_neighbor_filter(dev_priv, pipe, id);
This should be sitting alongside the other register writes.
> +
> + /* Make the scaling window size to integer multiple of
> + * source.
> + *
> + * TODO: Should userspace take desision to round
> + * scaling window to integer multiple?
To give userspace actual control of the pfit window size we need the border
props (or something along those lines). Step 1 is
https://patchwork.freedesktop.org/series/68409/. There are further steps
in my branch after that, but it's still missing the border props for
eDP/LVDS/DSI since I was too lazy to think how they should interact with
the existing scaling mode prop.
> + */
> + pfit_w = rounddown(pfit_w,
> + (crtc_state->pipe_src_w << 16));
> + pfit_h = rounddown(pfit_h,
> + (crtc_state->pipe_src_h << 16));
> }
This part should be dropped as Daniel mentioned.
>
> hscale = (crtc_state->pipe_src_w << 16) / pfit_w;
> @@ -6271,8 +6352,6 @@ static void skl_pfit_enable(const struct intel_crtc_state *crtc_state)
> uv_rgb_hphase = skl_scaler_calc_phase(1, hscale, false);
> uv_rgb_vphase = skl_scaler_calc_phase(1, vscale, false);
>
> - id = scaler_state->scaler_id;
> -
> spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
>
> intel_de_write_fw(dev_priv, SKL_PS_CTRL(pipe, id),
I think we should also explicitly indicate here which cofficient set(s)
we're going to use, even if using set0 does mean those bits will be 0.
> diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
> index f92efbbec838..49f58d3c98fe 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.h
> +++ b/drivers/gpu/drm/i915/display/intel_display.h
> @@ -586,6 +586,8 @@ void intel_crtc_arm_fifo_underrun(struct intel_crtc *crtc,
> u16 skl_scaler_calc_phase(int sub, int scale, bool chroma_center);
> int skl_update_scaler_crtc(struct intel_crtc_state *crtc_state);
> void skl_scaler_disable(const struct intel_crtc_state *old_crtc_state);
> +void skl_setup_nearest_neighbor_filter(struct drm_i915_private *dev_priv,
> + enum pipe pipe, int scaler_id);
> void ilk_pfit_disable(const struct intel_crtc_state *old_crtc_state);
> u32 glk_plane_color_ctl(const struct intel_crtc_state *crtc_state,
> const struct intel_plane_state *plane_state);
> diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c b/drivers/gpu/drm/i915/display/intel_sprite.c
> index fd7b31a21723..5bef5c031374 100644
> --- a/drivers/gpu/drm/i915/display/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/display/intel_sprite.c
> @@ -415,18 +415,26 @@ skl_program_scaler(struct intel_plane *plane,
> u16 y_vphase, uv_rgb_vphase;
> int hscale, vscale;
> const struct drm_plane_state *state = &plane_state->uapi;
> + u32 src_w = drm_rect_width(&plane_state->uapi.src) >> 16;
> + u32 src_h = drm_rect_height(&plane_state->uapi.src) >> 16;
> u32 scaling_filter = PS_FILTER_MEDIUM;
> + struct drm_rect dst;
>
> if (state->scaling_filter == DRM_SCALING_FILTER_NEAREST_NEIGHBOR) {
> scaling_filter = PS_FILTER_PROGRAMMED;
> + skl_setup_nearest_neighbor_filter(dev_priv, pipe, scaler_id);
> +
> + /* Make the scaling window size to integer multiple of source
> + * TODO: Should userspace take desision to round scaling window
> + * to integer multiple?
> + */
> + crtc_w = rounddown(crtc_w, src_w);
> + crtc_h = rounddown(crtc_h, src_h);
> }
>
> - hscale = drm_rect_calc_hscale(&plane_state->uapi.src,
> - &plane_state->uapi.dst,
> - 0, INT_MAX);
> - vscale = drm_rect_calc_vscale(&plane_state->uapi.src,
> - &plane_state->uapi.dst,
> - 0, INT_MAX);
> + drm_rect_init(&dst, crtc_x, crtc_y, crtc_w, crtc_h);
Drop as well.
> + hscale = drm_rect_calc_hscale(&plane_state->uapi.src, &dst, 0, INT_MAX);
> + vscale = drm_rect_calc_vscale(&plane_state->uapi.src, &dst, 0, INT_MAX);
>
> /* TODO: handle sub-pixel coordinates */
> if (intel_format_info_is_yuv_semiplanar(fb->format, fb->modifier) &&
> --
> 2.23.0
--
Ville Syrjälä
Intel
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