Message-ID: <8207827.UIER1Ri0ED@avalon>
Date:   Thu, 26 Apr 2018 23:30:52 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
Cc:     linux-renesas-soc@...r.kernel.org, David Airlie <airlied@...ux.ie>,
        "open list:DRM DRIVERS FOR RENESAS" <dri-devel@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 05/17] drm: rcar-du: Split CRTC handling to support hardware indexing

Hi Kieran,

Thank you for the patch.

On Thursday, 26 April 2018 19:53:34 EEST Kieran Bingham wrote:
> The DU CRTC driver does not support distinguishing between a hardware
> index, and a software (CRTC) index in the event that a DU channel might
> not be populated by the hardware.
> 
> Support this by adapting the rcar_du_device_info structure to store a
> bitmask of available channels rather than a count of CRTCs. The count
> can then be obtained by determining the hamming weight of the bitmask.
> 
> This allows the rcar_du_crtc_create() function to distinguish between
> both index types, and non-populated DU channels will be skipped without
> leaving a gap in the software CRTC indexes.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 26 ++++++++++++++------------
>  drivers/gpu/drm/rcar-du/rcar_du_crtc.h |  3 ++-
>  drivers/gpu/drm/rcar-du/rcar_du_drv.c  | 20 ++++++++++----------
>  drivers/gpu/drm/rcar-du/rcar_du_drv.h  |  4 ++--
>  drivers/gpu/drm/rcar-du/rcar_du_kms.c  | 17 ++++++++++++-----
>  5 files changed, 40 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c index 5a15dfd66343..36ce194c13b5
> 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> @@ -902,7 +902,8 @@ static irqreturn_t rcar_du_crtc_irq(int irq, void *arg)
>   * Initialization
>   */
> 
> -int rcar_du_crtc_create(struct rcar_du_group *rgrp, unsigned int index)
> +int rcar_du_crtc_create(struct rcar_du_group *rgrp, unsigned int swindex,
> +			unsigned int hwindex)
>  {
>  	static const unsigned int mmio_offsets[] = {
>  		DU0_REG_OFFSET, DU1_REG_OFFSET, DU2_REG_OFFSET, DU3_REG_OFFSET
> @@ -910,7 +911,7 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp,
> unsigned int index)
> 
>  	struct rcar_du_device *rcdu = rgrp->dev;
>  	struct platform_device *pdev = to_platform_device(rcdu->dev);
> -	struct rcar_du_crtc *rcrtc = &rcdu->crtcs[index];
> +	struct rcar_du_crtc *rcrtc = &rcdu->crtcs[swindex];
>  	struct drm_crtc *crtc = &rcrtc->crtc;
>  	struct drm_plane *primary;
>  	unsigned int irqflags;
> @@ -922,7 +923,7 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp,
> unsigned int index)
> 
>  	/* Get the CRTC clock and the optional external clock. */
>  	if (rcar_du_has(rcdu, RCAR_DU_FEATURE_CRTC_IRQ_CLOCK)) {
> -		sprintf(clk_name, "du.%u", index);
> +		sprintf(clk_name, "du.%u", hwindex);
>  		name = clk_name;
>  	} else {
>  		name = NULL;
> @@ -930,16 +931,16 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp,
> unsigned int index)
> 
>  	rcrtc->clock = devm_clk_get(rcdu->dev, name);
>  	if (IS_ERR(rcrtc->clock)) {
> -		dev_err(rcdu->dev, "no clock for CRTC %u\n", index);
> +		dev_err(rcdu->dev, "no clock for CRTC %u\n", swindex);

How about

		dev_err(rcdu->dev, "no clock for DU channel %u\n", hwindex);

I think that would be clearer, because at this stage we're dealing with 
hardware resources, so matching the datasheet numbers seems better to me.

>  		return PTR_ERR(rcrtc->clock);
>  	}
> 
> -	sprintf(clk_name, "dclkin.%u", index);
> +	sprintf(clk_name, "dclkin.%u", hwindex);
>  	clk = devm_clk_get(rcdu->dev, clk_name);
>  	if (!IS_ERR(clk)) {
>  		rcrtc->extclock = clk;
>  	} else if (PTR_ERR(rcrtc->clock) == -EPROBE_DEFER) {
> -		dev_info(rcdu->dev, "can't get external clock %u\n", index);
> +		dev_info(rcdu->dev, "can't get external clock %u\n", hwindex);
>  		return -EPROBE_DEFER;
>  	}
> 
> @@ -948,13 +949,13 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp,
> unsigned int index) spin_lock_init(&rcrtc->vblank_lock);
> 
>  	rcrtc->group = rgrp;
> -	rcrtc->mmio_offset = mmio_offsets[index];
> -	rcrtc->index = index;
> +	rcrtc->mmio_offset = mmio_offsets[hwindex];
> +	rcrtc->index = hwindex;
> 
>  	if (rcar_du_has(rcdu, RCAR_DU_FEATURE_VSP1_SOURCE))
>  		primary = &rcrtc->vsp->planes[rcrtc->vsp_pipe].plane;
>  	else
> -		primary = &rgrp->planes[index % 2].plane;
> +		primary = &rgrp->planes[hwindex % 2].plane;

This shouldn't make a difference because when RCAR_DU_FEATURE_VSP1_SOURCE 
isn't set we're running on Gen2, and don't need to deal with indices, but from 
a conceptual point of view, wouldn't the software index be better here ? 
Missing hardware channels won't be visible from userspace, so taking the first 
plane of the group as the primary plane would seem better to me.

>  	ret = drm_crtc_init_with_planes(rcdu->ddev, crtc, primary, NULL,
>  					rcdu->info->gen <= 2 ?
> @@ -970,7 +971,8 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp,
> unsigned int index)
> 
>  	/* Register the interrupt handler. */
>  	if (rcar_du_has(rcdu, RCAR_DU_FEATURE_CRTC_IRQ_CLOCK)) {
> -		irq = platform_get_irq(pdev, index);
> +		/* The IRQ's are associated with the CRTC (sw)index */

s/index/index./

> +		irq = platform_get_irq(pdev, swindex);
>  		irqflags = 0;
>  	} else {
>  		irq = platform_get_irq(pdev, 0);
> @@ -978,7 +980,7 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp,
> unsigned int index) }
> 
>  	if (irq < 0) {
> -		dev_err(rcdu->dev, "no IRQ for CRTC %u\n", index);
> +		dev_err(rcdu->dev, "no IRQ for CRTC %u\n", swindex);
>  		return irq;
>  	}
> 
> @@ -986,7 +988,7 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp,
> unsigned int index) dev_name(rcdu->dev), rcrtc);
>  	if (ret < 0) {
>  		dev_err(rcdu->dev,
> -			"failed to register IRQ for CRTC %u\n", index);
> +			"failed to register IRQ for CRTC %u\n", swindex);
>  		return ret;
>  	}
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h index 518ee2c60eb8..5f003a16abc5
> 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> @@ -99,7 +99,8 @@ enum rcar_du_output {
>  	RCAR_DU_OUTPUT_MAX,
>  };
> 
> -int rcar_du_crtc_create(struct rcar_du_group *rgrp, unsigned int index);
> +int rcar_du_crtc_create(struct rcar_du_group *rgrp, unsigned int swindex,
> +			unsigned int hwindex);
>  void rcar_du_crtc_suspend(struct rcar_du_crtc *rcrtc);
>  void rcar_du_crtc_resume(struct rcar_du_crtc *rcrtc);
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> b/drivers/gpu/drm/rcar-du/rcar_du_drv.c index 05745e86d73e..d6ebc628fc22
> 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> @@ -40,7 +40,7 @@ static const struct rcar_du_device_info
> rzg1_du_r8a7743_info = { .gen = 2,
>  	.features = RCAR_DU_FEATURE_CRTC_IRQ_CLOCK
>  		  | RCAR_DU_FEATURE_EXT_CTRL_REGS,
> -	.num_crtcs = 2,
> +	.channel_mask = BIT(0) | BIT(1),

I'd write it BIT(1) | BIT(0) to match the usual little-endian order. Same 
comment for the other info structure instances.

>  	.routes = {
>  		/*
>  		 * R8A7743 has one RGB output and one LVDS output
> @@ -61,7 +61,7 @@ static const struct rcar_du_device_info
> rzg1_du_r8a7745_info = { .gen = 2,
>  	.features = RCAR_DU_FEATURE_CRTC_IRQ_CLOCK
>  		  | RCAR_DU_FEATURE_EXT_CTRL_REGS,
> -	.num_crtcs = 2,
> +	.channel_mask = BIT(0) | BIT(1),
>  	.routes = {
>  		/*
>  		 * R8A7745 has two RGB outputs
> @@ -80,7 +80,7 @@ static const struct rcar_du_device_info
> rzg1_du_r8a7745_info = { static const struct rcar_du_device_info
> rcar_du_r8a7779_info = {
>  	.gen = 2,
>  	.features = 0,
> -	.num_crtcs = 2,
> +	.channel_mask = BIT(0) | BIT(1),
>  	.routes = {
>  		/*
>  		 * R8A7779 has two RGB outputs and one (currently unsupported)
> @@ -102,7 +102,7 @@ static const struct rcar_du_device_info
> rcar_du_r8a7790_info = { .features = RCAR_DU_FEATURE_CRTC_IRQ_CLOCK
>  		  | RCAR_DU_FEATURE_EXT_CTRL_REGS,
>  	.quirks = RCAR_DU_QUIRK_ALIGN_128B,
> -	.num_crtcs = 3,
> +	.channel_mask = BIT(0) | BIT(1) | BIT(2),
>  	.routes = {
>  		/*
>  		 * R8A7790 has one RGB output, two LVDS outputs and one
> @@ -129,7 +129,7 @@ static const struct rcar_du_device_info
> rcar_du_r8a7791_info = { .gen = 2,
>  	.features = RCAR_DU_FEATURE_CRTC_IRQ_CLOCK
>  		  | RCAR_DU_FEATURE_EXT_CTRL_REGS,
> -	.num_crtcs = 2,
> +	.channel_mask = BIT(0) | BIT(1),
>  	.routes = {
>  		/*
>  		 * R8A779[13] has one RGB output, one LVDS output and one
> @@ -151,7 +151,7 @@ static const struct rcar_du_device_info
> rcar_du_r8a7792_info = { .gen = 2,
>  	.features = RCAR_DU_FEATURE_CRTC_IRQ_CLOCK
>  		  | RCAR_DU_FEATURE_EXT_CTRL_REGS,
> -	.num_crtcs = 2,
> +	.channel_mask = BIT(0) | BIT(1),
>  	.routes = {
>  		/* R8A7792 has two RGB outputs. */
>  		[RCAR_DU_OUTPUT_DPAD0] = {
> @@ -169,7 +169,7 @@ static const struct rcar_du_device_info
> rcar_du_r8a7794_info = { .gen = 2,
>  	.features = RCAR_DU_FEATURE_CRTC_IRQ_CLOCK
>  		  | RCAR_DU_FEATURE_EXT_CTRL_REGS,
> -	.num_crtcs = 2,
> +	.channel_mask = BIT(0) | BIT(1),
>  	.routes = {
>  		/*
>  		 * R8A7794 has two RGB outputs and one (currently unsupported)
> @@ -191,7 +191,7 @@ static const struct rcar_du_device_info
> rcar_du_r8a7795_info = { .features = RCAR_DU_FEATURE_CRTC_IRQ_CLOCK
>  		  | RCAR_DU_FEATURE_EXT_CTRL_REGS
>  		  | RCAR_DU_FEATURE_VSP1_SOURCE,
> -	.num_crtcs = 4,
> +	.channel_mask = BIT(0) | BIT(1) | BIT(2) | BIT(3),
>  	.routes = {
>  		/*
>  		 * R8A7795 has one RGB output, two HDMI outputs and one
> @@ -223,7 +223,7 @@ static const struct rcar_du_device_info
> rcar_du_r8a7796_info = { .features = RCAR_DU_FEATURE_CRTC_IRQ_CLOCK
>  		  | RCAR_DU_FEATURE_EXT_CTRL_REGS
>  		  | RCAR_DU_FEATURE_VSP1_SOURCE,
> -	.num_crtcs = 3,
> +	.channel_mask = BIT(0) | BIT(1) | BIT(2),
>  	.routes = {
>  		/*
>  		 * R8A7796 has one RGB output, one LVDS output and one HDMI
> @@ -251,7 +251,7 @@ static const struct rcar_du_device_info
> rcar_du_r8a77970_info = { .features = RCAR_DU_FEATURE_CRTC_IRQ_CLOCK
>  		  | RCAR_DU_FEATURE_EXT_CTRL_REGS
>  		  | RCAR_DU_FEATURE_VSP1_SOURCE,
> -	.num_crtcs = 1,
> +	.channel_mask = BIT(0),
>  	.routes = {
>  		/* R8A77970 has one RGB output and one LVDS output. */
>  		[RCAR_DU_OUTPUT_DPAD0] = {
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> b/drivers/gpu/drm/rcar-du/rcar_du_drv.h index 5c7ec15818c7..7a5de66deec2
> 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> @@ -52,7 +52,7 @@ struct rcar_du_output_routing {
>   * @gen: device generation (2 or 3)
>   * @features: device features (RCAR_DU_FEATURE_*)
>   * @quirks: device quirks (RCAR_DU_QUIRK_*)
> - * @num_crtcs: total number of CRTCs
> + * @channel_mask: bit mask of supported DU channels

Nitpicking, how about channels_mask ?

>   * @routes: array of CRTC to output routes, indexed by output
> (RCAR_DU_OUTPUT_*) * @num_lvds: number of internal LVDS encoders
>   */
> @@ -60,7 +60,7 @@ struct rcar_du_device_info {
>  	unsigned int gen;
>  	unsigned int features;
>  	unsigned int quirks;
> -	unsigned int num_crtcs;
> +	unsigned int channel_mask;
>  	struct rcar_du_output_routing routes[RCAR_DU_OUTPUT_MAX];
>  	unsigned int num_lvds;
>  	unsigned int dpll_ch;
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> b/drivers/gpu/drm/rcar-du/rcar_du_kms.c index cf5b422fc753..19a445fbc879
> 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> @@ -559,6 +559,7 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
>  	struct drm_fbdev_cma *fbdev;
>  	unsigned int num_encoders;
>  	unsigned int num_groups;
> +	unsigned int swi, hwi;

One variable per line please. I would also call them swindex and hwindex, that 
would be clearer in my opinion.

>  	unsigned int i;
>  	int ret;
> 
> @@ -571,7 +572,7 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
>  	dev->mode_config.funcs = &rcar_du_mode_config_funcs;
>  	dev->mode_config.helper_private = &rcar_du_mode_config_helper;
> 
> -	rcdu->num_crtcs = rcdu->info->num_crtcs;
> +	rcdu->num_crtcs = hweight8(rcdu->info->channel_mask);
> 
>  	ret = rcar_du_properties_init(rcdu);
>  	if (ret < 0)
> @@ -581,7 +582,7 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
>  	 * Initialize vertical blanking interrupts handling. Start with vblank
>  	 * disabled for all CRTCs.
>  	 */
> -	ret = drm_vblank_init(dev, (1 << rcdu->info->num_crtcs) - 1);
> +	ret = drm_vblank_init(dev, (1 << rcdu->num_crtcs) - 1);
>  	if (ret < 0)
>  		return ret;
> 
> @@ -623,10 +624,16 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
>  	}
> 
>  	/* Create the CRTCs. */
> -	for (i = 0; i < rcdu->num_crtcs; ++i) {
> -		struct rcar_du_group *rgrp = &rcdu->groups[i / 2];
> +	for (swi = 0, hwi = 0; swi < rcdu->num_crtcs; ++hwi) {
> +		struct rcar_du_group *rgrp;
> +
> +		/* Skip unpopulated DU channels */

s/channels/channels./

> +		if (!(rcdu->info->channel_mask & BIT(hwi)))
> +			continue;
> +
> +		rgrp = &rcdu->groups[hwi / 2];
> 
> -		ret = rcar_du_crtc_create(rgrp, i);
> +		ret = rcar_du_crtc_create(rgrp, swi++, hwi);
>  		if (ret < 0)
>  			return ret;
>  	}

This is going to turn into an infinite loop if we ever get the num_crtcs 
calculation wrong, but I don't see why that should be the case, so I'm OK with 
the implementation.

With all those small issues fixed,

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

-- 
Regards,

Laurent Pinchart

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