Re: [RFC 1/2] drm/i915/display: add improved crtc iterators

[Jani Nikula <jani.nikula@intel.com>]

On Thu, 19 Sep 2024, Jani Nikula <jani.nikula@intel.com> wrote:
> The macros for iterating crtcs have become unweildy. Add a more generic
> solution.
>
> This is extensible via new initialization functions, more pipe_masks,
> and dedicated .get_next() functions.
>
> Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/Makefile                 |  1 +
>  .../gpu/drm/i915/display/intel_crtc_iter.c    | 94 +++++++++++++++++++
>  .../gpu/drm/i915/display/intel_crtc_iter.h    | 87 +++++++++++++++++
>  drivers/gpu/drm/xe/Makefile                   |  1 +
>  4 files changed, 183 insertions(+)
>  create mode 100644 drivers/gpu/drm/i915/display/intel_crtc_iter.c
>  create mode 100644 drivers/gpu/drm/i915/display/intel_crtc_iter.h
>
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index bb67bad839ea..7a370cc91dcb 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -232,6 +232,7 @@ i915-y += \
>  	display/intel_combo_phy.o \
>  	display/intel_connector.o \
>  	display/intel_crtc.o \
> +	display/intel_crtc_iter.o \
>  	display/intel_crtc_state_dump.o \
>  	display/intel_cursor.o \
>  	display/intel_display.o \
> diff --git a/drivers/gpu/drm/i915/display/intel_crtc_iter.c b/drivers/gpu/drm/i915/display/intel_crtc_iter.c
> new file mode 100644
> index 000000000000..27f16b565a67
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/display/intel_crtc_iter.c
> @@ -0,0 +1,94 @@
> +// SPDX-License-Identifier: MIT
> +/* Copyright © 2024 Intel Corporation */
> +
> +#include <linux/list.h>
> +#include <linux/kernel.h>
> +
> +#include "intel_crtc_iter.h"
> +#include "intel_display.h"
> +#include "intel_display_core.h"
> +#include "intel_display_types.h"
> +
> +static void reset_pos(struct intel_crtc_iter *iter)
> +{
> +	if (iter->reverse)
> +		iter->pos = list_last_entry(iter->crtc_list, typeof(*iter->pos), base.head);
> +	else
> +		iter->pos = list_first_entry(iter->crtc_list, typeof(*iter->pos), base.head);
> +}
> +
> +static struct intel_crtc *get_next(struct intel_crtc_iter *iter)
> +{
> +	if (iter->reverse) {
> +		list_for_each_entry_from(iter->pos, iter->crtc_list, base.head) {
> +			if (iter->pipe_mask[iter->pipe_mask_index] & BIT(iter->pos->pipe))
> +				return iter->pos;
> +		}
> +	} else {
> +		list_for_each_entry_from_reverse(iter->pos, iter->crtc_list, base.head) {
> +			if (iter->pipe_mask[iter->pipe_mask_index] & BIT(iter->pos->pipe))
> +				return iter->pos;
> +		}
> +	}

It's getting late, the blocks for the above are the wrong way around.

> +
> +	/* List exhausted, start over with the next pipe mask, if any. */
> +	iter->pipe_mask_index++;
> +	if (iter->pipe_mask_index < ARRAY_SIZE(iter->pipe_mask) &&
> +	    iter->pipe_mask[iter->pipe_mask_index]) {
> +		reset_pos(iter);
> +		return get_next(iter);
> +	}
> +
> +	return NULL;
> +}
> +
> +/*
> + * Iterate all CRTCs in forward or reverse CRTC initialization order, depending
> + * on reverse parameter, first matching pipes in pipe_mask0, then the pipes in
> + * pipe_mask1.
> + */
> +void __intel_crtc_iter_begin(struct intel_display *display,
> +			     struct intel_crtc_iter *iter,
> +			     unsigned long pipe_mask0,
> +			     unsigned long pipe_mask1,
> +			     bool reverse)
> +{
> +	iter->crtc_list = &display->drm->mode_config.crtc_list;
> +	iter->reverse = reverse;
> +	reset_pos(iter);
> +	iter->get_next = get_next;
> +	iter->pipe_mask_index = 0;
> +	iter->pipe_mask[0] = pipe_mask0;
> +	iter->pipe_mask[1] = pipe_mask1;
> +
> +	/* It's an error to match the same pipe twice. */
> +	drm_WARN_ON(display->drm, pipe_mask0 & pipe_mask1);
> +}
> +
> +
> +void intel_crtc_iter_end(struct intel_crtc_iter *iter)
> +{
> +	memset(iter, 0, sizeof(*iter));
> +}
> +
> +void intel_crtc_iter_begin_modeset_enable(struct intel_display *display,
> +					  struct intel_crtc_iter *iter,
> +					  const struct intel_crtc_state *crtc_state)
> +{
> +	/* Enable secondary pipes first, then the primary pipes. */
> +	__intel_crtc_iter_begin(display, iter,
> +				_intel_modeset_secondary_pipes(crtc_state),
> +				_intel_modeset_primary_pipes(crtc_state),
> +				false);
> +}
> +
> +void intel_crtc_iter_begin_modeset_disable(struct intel_display *display,
> +					   struct intel_crtc_iter *iter,
> +					   const struct intel_crtc_state *crtc_state)
> +{
> +	/* Disable primary pipes first, then the secondary pipes. */
> +	__intel_crtc_iter_begin(display, iter,
> +				_intel_modeset_primary_pipes(crtc_state),
> +				_intel_modeset_secondary_pipes(crtc_state),
> +				true);
> +}
> diff --git a/drivers/gpu/drm/i915/display/intel_crtc_iter.h b/drivers/gpu/drm/i915/display/intel_crtc_iter.h
> new file mode 100644
> index 000000000000..ec8d7ea3d595
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/display/intel_crtc_iter.h
> @@ -0,0 +1,87 @@
> +/* SPDX-License-Identifier: MIT */
> +/* Copyright © 2024 Intel Corporation */
> +
> +/*
> + * struct intel_crtc iterators for various needs.
> + *
> + * Usage:
> + *
> + *	struct intel_crtc *crtc;
> + *	struct intel_crtc_iter iter;
> + *
> + *	intel_crtc_iter_begin(display, &iter);
> + *	intel_crtc_iter_for_each(crtc, &iter) {
> + *		...
> + *	}
> + *	intel_crtc_iter_end(&iter);
> + *
> + * There are various alternatives to intel_crtc_iter_begin() that change the
> + * iteration behaviour, but the rest remains the same in all cases.
> + */
> +
> +#ifndef __INTEL_CRTC_ITER_H__
> +#define __INTEL_CRTC_ITER_H__
> +
> +#include <linux/types.h>
> +
> +struct intel_crtc;
> +struct intel_crtc_state;
> +struct intel_display;
> +struct list_head;
> +
> +/* This is private. Do not look insde. */
> +struct intel_crtc_iter {
> +	struct list_head *crtc_list;
> +	struct intel_crtc *pos;
> +	struct intel_crtc *(*get_next)(struct intel_crtc_iter *iter);
> +	int pipe_mask_index;
> +	u32 pipe_mask[2];
> +	bool reverse;
> +};
> +
> +void __intel_crtc_iter_begin(struct intel_display *display,
> +			     struct intel_crtc_iter *iter,
> +			     unsigned long pipe_mask0,
> +			     unsigned long pipe_mask1,
> +			     bool reverse);
> +
> +static inline void intel_crtc_iter_begin(struct intel_display *display,
> +					 struct intel_crtc_iter *iter)
> +{
> +	__intel_crtc_iter_begin(display, iter, ~0UL, 0, false);
> +}
> +
> +static inline void intel_crtc_iter_begin_reverse(struct intel_display *display,
> +						 struct intel_crtc_iter *iter)
> +{
> +	__intel_crtc_iter_begin(display, iter, ~0UL, 0, true);
> +}
> +
> +static inline void intel_crtc_iter_begin_pipe_mask(struct intel_display *display,
> +						   struct intel_crtc_iter *iter,
> +						   unsigned long pipe_mask)
> +{
> +	__intel_crtc_iter_begin(display, iter, pipe_mask, 0, false);
> +}
> +
> +static inline void intel_crtc_iter_begin_pipe_mask_reverse(struct intel_display *display,
> +							   struct intel_crtc_iter *iter,
> +							   unsigned long pipe_mask)
> +{
> +	__intel_crtc_iter_begin(display, iter, pipe_mask, 0, true);
> +}
> +
> +void intel_crtc_iter_begin_modeset_enable(struct intel_display *display,
> +					  struct intel_crtc_iter *iter,
> +					  const struct intel_crtc_state *crtc_state);
> +
> +void intel_crtc_iter_begin_modeset_disable(struct intel_display *display,
> +					   struct intel_crtc_iter *iter,
> +					   const struct intel_crtc_state *crtc_state);
> +
> +#define intel_crtc_iter_for_each(crtc, iter) \
> +	while (((crtc) = (iter)->get_next(iter)))
> +
> +void intel_crtc_iter_end(struct intel_crtc_iter *iter);
> +
> +#endif /* __INTEL_CRTC_ITER_H__ */
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index ae245fbd91ee..e1c8111b2528 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -198,6 +198,7 @@ xe-$(CONFIG_DRM_XE_DISPLAY) += \
>  	i915-display/intel_combo_phy.o \
>  	i915-display/intel_connector.o \
>  	i915-display/intel_crtc.o \
> +	i915-display/intel_crtc_iter.o \
>  	i915-display/intel_crtc_state_dump.o \
>  	i915-display/intel_cursor.o \
>  	i915-display/intel_cx0_phy.o \

-- 
Jani Nikula, Intel