Message-ID: <1755644.VLH7GnMWUR@steina-w>
Date:   Tue, 14 Feb 2023 15:12:55 +0100
From:   Alexander Stein <alexander.stein@...tq-group.com>
To:     dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Liu Ying <victor.liu@....com>
Cc:     marex@...x.de, stefan@...er.ch, airlied@...il.com, daniel@...ll.ch,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
        festevam@...il.com, linux-imx@....com,
        krzysztof.kozlowski@...aro.org, LW@...o-electronics.de
Subject: Re: [PATCH v3 3/6] drm: lcdif: Determine bus format and flags in ->atomic_check()

Hi Liu,

thanks for the update.

Am Montag, 13. Februar 2023, 09:56:09 CET schrieb Liu Ying:
> Instead of determining LCDIF output bus format and bus flags in
> ->atomic_enable(), do that in ->atomic_check().  This is a
> preparation for the upcoming patch to check consistent bus format
> and bus flags across all first downstream bridges in ->atomic_check().
> New lcdif_crtc_state structure is introduced to cache bus format
> and bus flags states in ->atomic_check() so that they can be read
> in ->atomic_enable().
> 
> Signed-off-by: Liu Ying <victor.liu@....com>
> ---
> v2->v3:
> * No change.
> 
> v1->v2:
> * Split from patch 2/2 in v1. (Marek, Alexander)
> * Add comment on the 'base' member of lcdif_crtc_state structure to
>   note it should always be the first member. (Lothar)
> 
>  drivers/gpu/drm/mxsfb/lcdif_kms.c | 138 ++++++++++++++++++++++--------
>  1 file changed, 100 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> b/drivers/gpu/drm/mxsfb/lcdif_kms.c index e54200a9fcb9..294cecdf5439 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> @@ -30,6 +30,18 @@
>  #include "lcdif_drv.h"
>  #include "lcdif_regs.h"
> 
> +struct lcdif_crtc_state {
> +	struct drm_crtc_state	base;	/* always be the first 
member */

Is it strictly necessary that base is the first member? to_lcdif_crtc_state() 
should be able to handle any position within the struct. I mean it's sensible 
to put it in first place. But the comment somehow bugs me.

> +	u32			bus_format;
> +	u32			bus_flags;
> +};
> +
> +static inline struct lcdif_crtc_state *
> +to_lcdif_crtc_state(struct drm_crtc_state *s)
> +{
> +	return container_of(s, struct lcdif_crtc_state, base);
> +}
> +
>  /*
> ---------------------------------------------------------------------------
> -- * CRTC
>   */
> @@ -385,48 +397,72 @@ static void lcdif_reset_block(struct lcdif_drm_private
> *lcdif) readl(lcdif->base + LCDC_V8_CTRL);
>  }
> 
> -static void lcdif_crtc_mode_set_nofb(struct lcdif_drm_private *lcdif,
> -				     struct drm_plane_state 
*plane_state,
> -				     struct drm_bridge_state 
*bridge_state,
> -				     const u32 bus_format)
> +static void lcdif_crtc_mode_set_nofb(struct drm_crtc_state *crtc_state,
> +				     struct drm_plane_state 
*plane_state)
>  {
> -	struct drm_device *drm = lcdif->crtc.dev;
> -	struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
> -	u32 bus_flags = 0;
> -
> -	if (lcdif->bridge->timings)
> -		bus_flags = lcdif->bridge->timings->input_bus_flags;
> -	else if (bridge_state)
> -		bus_flags = bridge_state->input_bus_cfg.flags;
> +	struct lcdif_crtc_state *lcdif_crtc_state =
> to_lcdif_crtc_state(crtc_state); +	struct drm_device *drm =
> crtc_state->crtc->dev;
> +	struct lcdif_drm_private *lcdif = to_lcdif_drm_private(drm);
> +	struct drm_display_mode *m = &crtc_state->adjusted_mode;
> 
>  	DRM_DEV_DEBUG_DRIVER(drm->dev, "Pixel clock: %dkHz (actual: %dkHz)
\n",
>  			     m->crtc_clock,
>  			     (int)(clk_get_rate(lcdif->clk) / 1000));
>  	DRM_DEV_DEBUG_DRIVER(drm->dev, "Bridge bus_flags: 0x%08X\n",
> -			     bus_flags);
> +			     lcdif_crtc_state->bus_flags);
>  	DRM_DEV_DEBUG_DRIVER(drm->dev, "Mode flags: 0x%08X\n", m->flags);
> 
>  	/* Mandatory eLCDIF reset as per the Reference Manual */
>  	lcdif_reset_block(lcdif);
> 
> -	lcdif_set_formats(lcdif, plane_state, bus_format);
> +	lcdif_set_formats(lcdif, plane_state, lcdif_crtc_state->bus_format);
> 
> -	lcdif_set_mode(lcdif, bus_flags);
> +	lcdif_set_mode(lcdif, lcdif_crtc_state->bus_flags);
>  }
> 
>  static int lcdif_crtc_atomic_check(struct drm_crtc *crtc,
>  				   struct drm_atomic_state *state)
>  {
> +	struct drm_device *drm = crtc->dev;
> +	struct lcdif_drm_private *lcdif = to_lcdif_drm_private(drm);
>  	struct drm_crtc_state *crtc_state = 
drm_atomic_get_new_crtc_state(state,
>  								
	  crtc);
> +	struct lcdif_crtc_state *lcdif_crtc_state =
> to_lcdif_crtc_state(crtc_state); bool has_primary = crtc_state->plane_mask
> &
>  			   drm_plane_mask(crtc->primary);
> +	struct drm_bridge_state *bridge_state;
> +	struct drm_bridge *bridge = lcdif->bridge;
> +	int ret;
> 
>  	/* The primary plane has to be enabled when the CRTC is active. */
>  	if (crtc_state->active && !has_primary)
>  		return -EINVAL;
> 
> -	return drm_atomic_add_affected_planes(state, crtc);
> +	ret = drm_atomic_add_affected_planes(state, crtc);
> +	if (ret)
> +		return ret;
> +
> +	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
> +	if (!bridge_state)
> +		lcdif_crtc_state->bus_format = MEDIA_BUS_FMT_FIXED;
> +	else
> +		lcdif_crtc_state->bus_format = bridge_state-
>input_bus_cfg.format;
> +
> +	if (lcdif_crtc_state->bus_format == MEDIA_BUS_FMT_FIXED) {
> +		dev_warn_once(drm->dev,
> +			      "Bridge does not provide bus format, 
assuming
> MEDIA_BUS_FMT_RGB888_1X24.\n" +			      "Please fix 
bridge driver by
> handling atomic_get_input_bus_fmts.\n"); +		lcdif_crtc_state-
>bus_format =
> MEDIA_BUS_FMT_RGB888_1X24;
> +	}
> +
> +	if (bridge->timings)
> +		lcdif_crtc_state->bus_flags = bridge->timings-
>input_bus_flags;
> +	else if (bridge_state)
> +		lcdif_crtc_state->bus_flags = bridge_state-
>input_bus_cfg.flags;
> +	else
> +		lcdif_crtc_state->bus_flags = 0;
> +
> +	return 0;
>  }
> 
>  static void lcdif_crtc_atomic_flush(struct drm_crtc *crtc,
> @@ -458,35 +494,21 @@ static void lcdif_crtc_atomic_enable(struct drm_crtc
> *crtc, struct drm_atomic_state *state)
>  {
>  	struct lcdif_drm_private *lcdif = to_lcdif_drm_private(crtc->dev);
> -	struct drm_plane_state *new_pstate = 
drm_atomic_get_new_plane_state(state,
> -								
	    crtc->primary);
> +	struct drm_crtc_state *new_crtc_state =
> drm_atomic_get_new_crtc_state(state, crtc); +	struct drm_plane_state
> *new_plane_state = drm_atomic_get_new_plane_state(state, +			
							
> crtc->primary);

While the rename to 'new_plane_state' makes sense, this is an unrelated 
change.

>  	struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
> -	struct drm_bridge_state *bridge_state = NULL;
>  	struct drm_device *drm = lcdif->drm;
> -	u32 bus_format;
>  	dma_addr_t paddr;
> 
> -	bridge_state = drm_atomic_get_new_bridge_state(state, lcdif-
>bridge);
> -	if (!bridge_state)
> -		bus_format = MEDIA_BUS_FMT_FIXED;
> -	else
> -		bus_format = bridge_state->input_bus_cfg.format;
> -
> -	if (bus_format == MEDIA_BUS_FMT_FIXED) {
> -		dev_warn_once(drm->dev,
> -			      "Bridge does not provide bus format, 
assuming
> MEDIA_BUS_FMT_RGB888_1X24.\n" -			      "Please fix 
bridge driver by
> handling atomic_get_input_bus_fmts.\n"); -		bus_format =
> MEDIA_BUS_FMT_RGB888_1X24;
> -	}
> -
>  	clk_set_rate(lcdif->clk, m->crtc_clock * 1000);
> 
>  	pm_runtime_get_sync(drm->dev);
> 
> -	lcdif_crtc_mode_set_nofb(lcdif, new_pstate, bridge_state, 
bus_format);
> +	lcdif_crtc_mode_set_nofb(new_crtc_state, new_plane_state);
> 
>  	/* Write cur_buf as well to avoid an initial corrupt frame */
> -	paddr = drm_fb_dma_get_gem_addr(new_pstate->fb, new_pstate, 0);
> +	paddr = drm_fb_dma_get_gem_addr(new_plane_state->fb, 
new_plane_state, 0);
>  	if (paddr) {
>  		writel(lower_32_bits(paddr),
>  		       lcdif->base + LCDC_V8_CTRLDESCL_LOW0_4);
> @@ -520,6 +542,46 @@ static void lcdif_crtc_atomic_disable(struct drm_crtc
> *crtc, pm_runtime_put_sync(drm->dev);
>  }
> 
> +static void lcdif_crtc_reset(struct drm_crtc *crtc)
> +{
> +	struct lcdif_crtc_state *state;
> +
> +	if (crtc->state)
> +		__drm_atomic_helper_crtc_destroy_state(crtc->state);
> +
> +	kfree(to_lcdif_crtc_state(crtc->state));

Shouldn't this be just
if (crtc->state)
	crtc->funcs->atomic_destroy_state(crtc, crtc->state);

similar to what drm_atomic_helper_crtc_reset is doing? This will eventually 
call lcdif_crtc_atomic_destroy_state().

> +	crtc->state = NULL;
> +
> +	state = kzalloc(sizeof(*state), GFP_KERNEL);
> +	if (state)
> +		__drm_atomic_helper_crtc_reset(crtc, &state->base);

Is there a specific reason to not call this helper when 'state==NULL'? 
drm_atomic_helper_crtc_reset() does call this even when passing NULL for 
crtc_state.

> +}
> +
> +static struct drm_crtc_state *
> +lcdif_crtc_atomic_duplicate_state(struct drm_crtc *crtc)
> +{
> +	struct lcdif_crtc_state *old = to_lcdif_crtc_state(crtc->state);
> +	struct lcdif_crtc_state *new;
> +

drm_atomic_helper_crtc_duplicate_state() has a check for
if (WARN_ON(!crtc->state))
	return NULL;

Maybe it should be added here as well. But then the call to 
to_lcdif_crtc_state() has to be moved down.

Best regards,
Alexander

> +	new = kzalloc(sizeof(*new), GFP_KERNEL);
> +	if (!new)
> +		return NULL;
> +
> +	__drm_atomic_helper_crtc_duplicate_state(crtc, &new->base);
> +
> +	new->bus_format = old->bus_format;
> +	new->bus_flags = old->bus_flags;
> +
> +	return &new->base;
> +}
> +
> +static void lcdif_crtc_atomic_destroy_state(struct drm_crtc *crtc,
> +					    struct drm_crtc_state 
*state)
> +{
> +	__drm_atomic_helper_crtc_destroy_state(state);
> +	kfree(to_lcdif_crtc_state(state));
> +}
> +
>  static int lcdif_crtc_enable_vblank(struct drm_crtc *crtc)
>  {
>  	struct lcdif_drm_private *lcdif = to_lcdif_drm_private(crtc->dev);
> @@ -548,12 +610,12 @@ static const struct drm_crtc_helper_funcs
> lcdif_crtc_helper_funcs = { };
> 
>  static const struct drm_crtc_funcs lcdif_crtc_funcs = {
> -	.reset = drm_atomic_helper_crtc_reset,
> +	.reset = lcdif_crtc_reset,
>  	.destroy = drm_crtc_cleanup,
>  	.set_config = drm_atomic_helper_set_config,
>  	.page_flip = drm_atomic_helper_page_flip,
> -	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
> -	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
> +	.atomic_duplicate_state = lcdif_crtc_atomic_duplicate_state,
> +	.atomic_destroy_state = lcdif_crtc_atomic_destroy_state,
>  	.enable_vblank = lcdif_crtc_enable_vblank,
>  	.disable_vblank = lcdif_crtc_disable_vblank,
>  };


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