Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
drm/i915/dp: Limit max link bpp properly to a fractional value on SST
The maximum link bpp - determined by the link BW for instance - can be
fractional, handle this properly during computing the link bpp on SST.
This keeps the pipe joiner specific maximum link bpp as a rounded-down
integer value still, changing that to a fractional value is left for
later.
v2: Align the min/max bpp value to the bpp step.
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250509180340.554867-8-imre.deak@intel.com
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drivers/gpu/drm/i915/display/intel_dp.c
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drivers/gpu/drm/i915/display/intel_dp.c
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#include <linux/export.h>
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#include <linux/i2c.h>
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+
#include <linux/log2.h>
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#include <linux/math.h>
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#include <linux/notifier.h>
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#include <linux/seq_buf.h>
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#include <linux/slab.h>
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return ultrajoiner_ram_bits() / mode_hdisplay;
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}
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+
/* TODO: return a bpp_x16 value */
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static
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u32 get_max_compressed_bpp_with_joiner(struct intel_display *display,
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u32 mode_clock, u32 mode_hdisplay,
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const struct intel_connector *connector = to_intel_connector(conn_state->connector);
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const struct drm_display_mode *adjusted_mode = &pipe_config->hw.adjusted_mode;
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int output_bpp;
2159
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int dsc_min_bpp;
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int dsc_max_bpp;
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int min_bpp_x16, max_bpp_x16, bpp_step_x16;
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int dsc_joiner_max_bpp;
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int num_joined_pipes = intel_crtc_num_joined_pipes(pipe_config);
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int bpp_x16;
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int ret;
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-
dsc_min_bpp = fxp_q4_to_int_roundup(limits->link.min_bpp_x16);
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dsc_joiner_max_bpp = get_max_compressed_bpp_with_joiner(display, adjusted_mode->clock,
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adjusted_mode->hdisplay,
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num_joined_pipes);
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dsc_max_bpp = min(dsc_joiner_max_bpp, fxp_q4_to_int(limits->link.max_bpp_x16));
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/* FIXME: remove the round trip via integers */
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min_bpp_x16 = fxp_q4_from_int(dsc_min_bpp);
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max_bpp_x16 = fxp_q4_from_int(dsc_max_bpp);
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max_bpp_x16 = min(fxp_q4_from_int(dsc_joiner_max_bpp), limits->link.max_bpp_x16);
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bpp_step_x16 = intel_dp_dsc_bpp_step_x16(connector);
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/* Compressed BPP should be less than the Input DSC bpp */
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output_bpp = intel_dp_output_bpp(pipe_config->output_format, pipe_bpp);
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max_bpp_x16 = min(max_bpp_x16, fxp_q4_from_int(output_bpp) - bpp_step_x16);
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drm_WARN_ON(display->drm, !is_power_of_2(bpp_step_x16));
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min_bpp_x16 = round_up(limits->link.min_bpp_x16, bpp_step_x16);
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max_bpp_x16 = round_down(max_bpp_x16, bpp_step_x16);
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for (bpp_x16 = max_bpp_x16; bpp_x16 >= min_bpp_x16; bpp_x16 -= bpp_step_x16) {
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if (!intel_dp_dsc_valid_compressed_bpp(intel_dp, bpp_x16))