linux/drivers/gpu/drm/i915/display/intel_link_bw.c

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2023 Intel Corporation
 */

#include <drm/drm_fixed.h>

#include "i915_drv.h"

#include "intel_atomic.h"
#include "intel_crtc.h"
#include "intel_display_types.h"
#include "intel_dp_mst.h"
#include "intel_dp_tunnel.h"
#include "intel_fdi.h"
#include "intel_link_bw.h"

/**
 * intel_link_bw_init_limits - initialize BW limits
 * @state: Atomic state
 * @limits: link BW limits
 *
 * Initialize @limits.
 */
void intel_link_bw_init_limits(struct intel_atomic_state *state,
			       struct intel_link_bw_limits *limits)
{ … }

/**
 * intel_link_bw_reduce_bpp - reduce maximum link bpp for a selected pipe
 * @state: atomic state
 * @limits: link BW limits
 * @pipe_mask: mask of pipes to select from
 * @reason: explanation of why bpp reduction is needed
 *
 * Select the pipe from @pipe_mask with the biggest link bpp value and set the
 * maximum of link bpp in @limits below this value. Modeset the selected pipe,
 * so that its state will get recomputed.
 *
 * This function can be called to resolve a link's BW overallocation by reducing
 * the link bpp of one pipe on the link and hence reducing the total link BW.
 *
 * Returns
 *   - 0 in case of success
 *   - %-ENOSPC if no pipe can further reduce its link bpp
 *   - Other negative error, if modesetting the selected pipe failed
 */
int intel_link_bw_reduce_bpp(struct intel_atomic_state *state,
			     struct intel_link_bw_limits *limits,
			     u8 pipe_mask,
			     const char *reason)
{ … }

/**
 * intel_link_bw_set_bpp_limit_for_pipe - set link bpp limit for a pipe to its minimum
 * @state: atomic state
 * @old_limits: link BW limits
 * @new_limits: link BW limits
 * @pipe: pipe
 *
 * Set the link bpp limit for @pipe in @new_limits to its value in
 * @old_limits and mark this limit as the minimum. This function must be
 * called after a pipe's compute config function failed, @old_limits
 * containing the bpp limit with which compute config previously passed.
 *
 * The function will fail if setting a minimum is not possible, either
 * because the old and new limits match (and so would lead to a pipe compute
 * config failure) or the limit is already at the minimum.
 *
 * Returns %true in case of success.
 */
bool
intel_link_bw_set_bpp_limit_for_pipe(struct intel_atomic_state *state,
				     const struct intel_link_bw_limits *old_limits,
				     struct intel_link_bw_limits *new_limits,
				     enum pipe pipe)
{ … }

static int check_all_link_config(struct intel_atomic_state *state,
				 struct intel_link_bw_limits *limits)
{ … }

static bool
assert_link_limit_change_valid(struct intel_display *display,
			       const struct intel_link_bw_limits *old_limits,
			       const struct intel_link_bw_limits *new_limits)
{ … }

/**
 * intel_link_bw_atomic_check - check display link states and set a fallback config if needed
 * @state: atomic state
 * @new_limits: link BW limits
 *
 * Check the configuration of all shared display links in @state and set new BW
 * limits in @new_limits if there is a BW limitation.
 *
 * Returns:
 *   - 0 if the confugration is valid
 *   - %-EAGAIN, if the configuration is invalid and @new_limits got updated
 *     with fallback values with which the configuration of all CRTCs
 *     in @state must be recomputed
 *   - Other negative error, if the configuration is invalid without a
 *     fallback possibility, or the check failed for another reason
 */
int intel_link_bw_atomic_check(struct intel_atomic_state *state,
			       struct intel_link_bw_limits *new_limits)
{ … }