Message-ID: <522ab8cb2939f0017917c5e9b4065089@aosc.io>
Date:   Fri, 05 May 2017 00:50:51 +0800
From:   icenowy@...c.io
To:     Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:     Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH v6 08/13] drm/sun4i: add support for Allwinner DE2 mixers

在 2017-05-04 21:05，Maxime Ripard 写道：
> On Thu, May 04, 2017 at 07:48:53PM +0800, Icenowy Zheng wrote:
>> Allwinner have a new "Display Engine 2.0" in their new SoCs, which 
>> comes
>> with mixers to do graphic processing and feed data to TCON, like the 
>> old
>> backends and frontends.
>> 
>> Add support for the mixer on Allwinner V3s SoC; it's the simplest one.
>> 
>> Currently a lot of functions are still missing -- more investigations
>> are needed to gain enough information for them.
>> 
>> Signed-off-by: Icenowy Zheng <icenowy@...c.io>
>> ---
>> Changes in v6:
>> - Rebased on wens's multi-pipeline patchset.
>> Changes in v5:
>> - Changed some code alignment.
>> - Request real 32-bit DMA (prepare for 64-bit SoCs).
>> Changes in v4:
>> - Killed some dead code according to Jernej.
>> 
>>  drivers/gpu/drm/sun4i/Kconfig       |  10 +
>>  drivers/gpu/drm/sun4i/Makefile      |   3 +
>>  drivers/gpu/drm/sun4i/sun8i_layer.c | 140 +++++++++++++
>>  drivers/gpu/drm/sun4i/sun8i_layer.h |  36 ++++
>>  drivers/gpu/drm/sun4i/sun8i_mixer.c | 394 
>> ++++++++++++++++++++++++++++++++++++
>>  drivers/gpu/drm/sun4i/sun8i_mixer.h | 137 +++++++++++++
>>  6 files changed, 720 insertions(+)
>>  create mode 100644 drivers/gpu/drm/sun4i/sun8i_layer.c
>>  create mode 100644 drivers/gpu/drm/sun4i/sun8i_layer.h
>>  create mode 100644 drivers/gpu/drm/sun4i/sun8i_mixer.c
>>  create mode 100644 drivers/gpu/drm/sun4i/sun8i_mixer.h
>> 
>> diff --git a/drivers/gpu/drm/sun4i/Kconfig 
>> b/drivers/gpu/drm/sun4i/Kconfig
>> index 5a8227f37cc4..15557484520d 100644
>> --- a/drivers/gpu/drm/sun4i/Kconfig
>> +++ b/drivers/gpu/drm/sun4i/Kconfig
>> @@ -22,3 +22,13 @@ config DRM_SUN4I_BACKEND
>>  	  original Allwinner Display Engine, which has a backend to
>>  	  do some alpha blending and feed graphics to TCON. If M is
>>  	  selected the module will be called sun4i-backend.
>> +
>> +config DRM_SUN4I_SUN8I_MIXER
> 
> DRM_SUN8I_MIXER?
> 
>> +	tristate "Support for Allwinner Display Engine 2.0 Mixer"
>> +	depends on DRM_SUN4I
>> +	default MACH_SUN8I
>> +	help
>> +	  Choose this option if you have an Allwinner SoC with the
>> +	  Allwinner Display Engine 2.0, which has a mixer to do some
>> +	  graphics mixture and feed graphics to TCON, If M is
>> +	  selected the module will be called sun8i-mixer.
>> diff --git a/drivers/gpu/drm/sun4i/Makefile 
>> b/drivers/gpu/drm/sun4i/Makefile
>> index a08df56759e3..a876c6b3027c 100644
>> --- a/drivers/gpu/drm/sun4i/Makefile
>> +++ b/drivers/gpu/drm/sun4i/Makefile
>> @@ -8,7 +8,10 @@ sun4i-tcon-y += sun4i_crtc.o
>> 
>>  sun4i-backend-y += sun4i_backend.o sun4i_layer.o
>> 
>> +sun8i-mixer-y += sun8i_mixer.o sun8i_layer.o
>> +
>>  obj-$(CONFIG_DRM_SUN4I)		+= sun4i-drm.o sun4i-tcon.o
>>  obj-$(CONFIG_DRM_SUN4I_BACKEND)		+= sun4i-backend.o
>> +obj-$(CONFIG_DRM_SUN4I_SUN8I_MIXER)	+= sun8i-mixer.o
>>  obj-$(CONFIG_DRM_SUN4I)		+= sun6i_drc.o
>>  obj-$(CONFIG_DRM_SUN4I)		+= sun4i_tv.o
>> diff --git a/drivers/gpu/drm/sun4i/sun8i_layer.c 
>> b/drivers/gpu/drm/sun4i/sun8i_layer.c
>> new file mode 100644
>> index 000000000000..48f33d8e013b
>> --- /dev/null
>> +++ b/drivers/gpu/drm/sun4i/sun8i_layer.c
>> @@ -0,0 +1,140 @@
>> +/*
>> + * Copyright (C) Icenowy Zheng <icenowy@...c.io>
>> + *
>> + * Based on sun4i_layer.h, which is:
>> + *   Copyright (C) 2015 Free Electrons
>> + *   Copyright (C) 2015 NextThing Co
>> + *
>> + *   Maxime Ripard <maxime.ripard@...e-electrons.com>
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License as
>> + * published by the Free Software Foundation; either version 2 of
>> + * the License, or (at your option) any later version.
>> + */
>> +
>> +#include <drm/drm_atomic_helper.h>
>> +#include <drm/drm_plane_helper.h>
>> +#include <drm/drmP.h>
>> +
>> +#include "sun8i_layer.h"
>> +#include "sun8i_mixer.h"
>> +
>> +struct sun8i_plane_desc {
>> +	       enum drm_plane_type     type;
>> +	       const uint32_t          *formats;
>> +	       uint32_t                nformats;
>> +};
>> +
>> +static int sun8i_mixer_layer_atomic_check(struct drm_plane *plane,
>> +					    struct drm_plane_state *state)
>> +{
>> +	return 0;
>> +}
> 
> This isn't needed.
> 
>> +static void sun8i_mixer_layer_atomic_disable(struct drm_plane *plane,
>> +					       struct drm_plane_state *old_state)
>> +{
>> +	struct sun8i_layer *layer = plane_to_sun8i_layer(plane);
>> +	struct sun8i_mixer *mixer = layer->mixer;
>> +
>> +	sun8i_mixer_layer_enable(mixer, layer->id, false);
>> +}
>> +
>> +static void sun8i_mixer_layer_atomic_update(struct drm_plane *plane,
>> +					      struct drm_plane_state *old_state)
>> +{
>> +	struct sun8i_layer *layer = plane_to_sun8i_layer(plane);
>> +	struct sun8i_mixer *mixer = layer->mixer;
>> +
>> +	sun8i_mixer_update_layer_coord(mixer, layer->id, plane);
>> +	sun8i_mixer_update_layer_formats(mixer, layer->id, plane);
>> +	sun8i_mixer_update_layer_buffer(mixer, layer->id, plane);
>> +	sun8i_mixer_layer_enable(mixer, layer->id, true);
>> +}
>> +
>> +static struct drm_plane_helper_funcs sun8i_mixer_layer_helper_funcs = 
>> {
>> +	.atomic_check	= sun8i_mixer_layer_atomic_check,
>> +	.atomic_disable	= sun8i_mixer_layer_atomic_disable,
>> +	.atomic_update	= sun8i_mixer_layer_atomic_update,
>> +};
>> +
>> +static const struct drm_plane_funcs sun8i_mixer_layer_funcs = {
>> +	.atomic_destroy_state	= drm_atomic_helper_plane_destroy_state,
>> +	.atomic_duplicate_state	= drm_atomic_helper_plane_duplicate_state,
>> +	.destroy		= drm_plane_cleanup,
>> +	.disable_plane		= drm_atomic_helper_disable_plane,
>> +	.reset			= drm_atomic_helper_plane_reset,
>> +	.update_plane		= drm_atomic_helper_update_plane,
>> +};
>> +
>> +static const uint32_t sun8i_mixer_layer_formats[] = {
>> +	DRM_FORMAT_RGB888,
>> +	DRM_FORMAT_XRGB8888,
>> +};
>> +
>> +static const struct sun8i_plane_desc sun8i_mixer_planes[] = {
>> +	{
>> +		.type = DRM_PLANE_TYPE_PRIMARY,
>> +		.formats = sun8i_mixer_layer_formats,
>> +		.nformats = ARRAY_SIZE(sun8i_mixer_layer_formats),
>> +	},
>> +};
>> +
>> +static struct sun8i_layer *sun8i_layer_init_one(struct drm_device 
>> *drm,
>> +						struct sun8i_mixer *mixer,
>> +						const struct sun8i_plane_desc *plane)
>> +{
>> +	struct sun8i_layer *layer;
>> +	int ret;
>> +
>> +	layer = devm_kzalloc(drm->dev, sizeof(*layer), GFP_KERNEL);
>> +	if (!layer)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	/* possible crtcs are set later */
>> +	ret = drm_universal_plane_init(drm, &layer->plane, 0,
>> +				       &sun8i_mixer_layer_funcs,
>> +				       plane->formats, plane->nformats,
>> +				       plane->type, NULL);
>> +	if (ret) {
>> +		dev_err(drm->dev, "Couldn't initialize layer\n");
>> +		return ERR_PTR(ret);
>> +	}
>> +
>> +	drm_plane_helper_add(&layer->plane,
>> +			     &sun8i_mixer_layer_helper_funcs);
>> +	layer->mixer = mixer;
>> +
>> +	return layer;
>> +}
>> +
>> +struct drm_plane **sun8i_layers_init(struct drm_device *drm,
>> +				     struct sunxi_engine *engine)
>> +{
>> +	struct drm_plane **planes;
>> +	struct sun8i_mixer *mixer = engine_to_sun8i_mixer(engine);
>> +	int i;
>> +
>> +	planes = devm_kcalloc(drm->dev, ARRAY_SIZE(sun8i_mixer_planes) + 1,
>> +			      sizeof(*planes), GFP_KERNEL);
>> +	if (!planes)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	for (i = 0; i < ARRAY_SIZE(sun8i_mixer_planes); i++) {
>> +		const struct sun8i_plane_desc *plane = &sun8i_mixer_planes[i];
>> +		struct sun8i_layer *layer;
>> +
>> +		layer = sun8i_layer_init_one(drm, mixer, plane);
>> +		if (IS_ERR(layer)) {
>> +			dev_err(drm->dev, "Couldn't initialize %s plane\n",
>> +				i ? "overlay" : "primary");
>> +			return ERR_CAST(layer);
>> +		};
>> +
>> +		layer->id = i;
>> +		planes[i] = &layer->plane;
>> +	};
>> +
>> +	return planes;
>> +}
>> diff --git a/drivers/gpu/drm/sun4i/sun8i_layer.h 
>> b/drivers/gpu/drm/sun4i/sun8i_layer.h
>> new file mode 100644
>> index 000000000000..e5eccd27cff0
>> --- /dev/null
>> +++ b/drivers/gpu/drm/sun4i/sun8i_layer.h
>> @@ -0,0 +1,36 @@
>> +/*
>> + * Copyright (C) Icenowy Zheng <icenowy@...c.io>
>> + *
>> + * Based on sun4i_layer.h, which is:
>> + *   Copyright (C) 2015 Free Electrons
>> + *   Copyright (C) 2015 NextThing Co
>> + *
>> + *   Maxime Ripard <maxime.ripard@...e-electrons.com>
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License as
>> + * published by the Free Software Foundation; either version 2 of
>> + * the License, or (at your option) any later version.
>> + */
>> +
>> +#ifndef _SUN8I_LAYER_H_
>> +#define _SUN8I_LAYER_H_
>> +
>> +struct sunxi_engine;
>> +
>> +struct sun8i_layer {
>> +	struct drm_plane	plane;
>> +	struct sun4i_drv	*drv;
>> +	struct sun8i_mixer	*mixer;
>> +	int			id;
>> +};
>> +
>> +static inline struct sun8i_layer *
>> +plane_to_sun8i_layer(struct drm_plane *plane)
>> +{
>> +	return container_of(plane, struct sun8i_layer, plane);
>> +}
>> +
>> +struct drm_plane **sun8i_layers_init(struct drm_device *drm,
>> +				     struct sunxi_engine *engine);
>> +#endif /* _SUN8I_LAYER_H_ */
>> diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.c 
>> b/drivers/gpu/drm/sun4i/sun8i_mixer.c
>> new file mode 100644
>> index 000000000000..e216b84d5bb2
>> --- /dev/null
>> +++ b/drivers/gpu/drm/sun4i/sun8i_mixer.c
>> @@ -0,0 +1,394 @@
>> +/*
>> + * Copyright (C) 2017 Icenowy Zheng <icenowy@...c.io>
>> + *
>> + * Based on sun4i_backend.c, which is:
>> + *   Copyright (C) 2015 Free Electrons
>> + *   Copyright (C) 2015 NextThing Co
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License as
>> + * published by the Free Software Foundation; either version 2 of
>> + * the License, or (at your option) any later version.
>> + */
>> +
>> +#include <drm/drmP.h>
>> +#include <drm/drm_atomic_helper.h>
>> +#include <drm/drm_crtc.h>
>> +#include <drm/drm_crtc_helper.h>
>> +#include <drm/drm_fb_cma_helper.h>
>> +#include <drm/drm_gem_cma_helper.h>
>> +#include <drm/drm_plane_helper.h>
>> +
>> +#include <linux/component.h>
>> +#include <linux/dma-mapping.h>
>> +#include <linux/reset.h>
>> +#include <linux/of_device.h>
>> +
>> +#include "sun4i_drv.h"
>> +#include "sun8i_mixer.h"
>> +#include "sun8i_layer.h"
>> +#include "sunxi_engine.h"
>> +
>> +void sun8i_mixer_commit(struct sunxi_engine *engine)
>> +{
>> +	DRM_DEBUG_DRIVER("Committing changes\n");
>> +
>> +	regmap_write(engine->regs, SUN8I_MIXER_GLOBAL_DBUFF,
>> +		     SUN8I_MIXER_GLOBAL_DBUFF_ENABLE);
>> +}
> 
> This function can be static
> 
>> +
>> +void sun8i_mixer_layer_enable(struct sun8i_mixer *mixer,
>> +				int layer, bool enable)
>> +{
>> +	u32 val;
>> +	/* Currently the first UI channel is used */
>> +	int chan = mixer->cfg->vi_num;
>> +
>> +	DRM_DEBUG_DRIVER("Enabling layer %d in channel %d\n", layer, chan);
>> +
>> +	if (enable)
>> +		val = SUN8I_MIXER_CHAN_UI_LAYER_ATTR_EN;
>> +	else
>> +		val = 0;
>> +
>> +	regmap_update_bits(mixer->engine.regs,
>> +			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR(chan, layer),
>> +			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR_EN, val);
>> +
>> +	/* Set the alpha configuration */
>> +	regmap_update_bits(mixer->engine.regs,
>> +			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR(chan, layer),
>> +			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MODE_MASK,
>> +			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MODE_DEF);
>> +	regmap_update_bits(mixer->engine.regs,
>> +			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR(chan, layer),
>> +			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MASK,
>> +			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_DEF);
>> +}
> 
> This one too.

It's called from sun8i_layer.c, so it cannot be static.

> 
>> +static int sun8i_mixer_drm_format_to_layer(struct drm_plane *plane,
>> +					     u32 format, u32 *mode)
>> +{
>> +	switch (format) {
>> +	case DRM_FORMAT_XRGB8888:
>> +		*mode = SUN8I_MIXER_CHAN_UI_LAYER_ATTR_FBFMT_XRGB8888;
>> +		break;
>> +
>> +	case DRM_FORMAT_RGB888:
>> +		*mode = SUN8I_MIXER_CHAN_UI_LAYER_ATTR_FBFMT_RGB888;
>> +		break;
>> +
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +int sun8i_mixer_update_layer_coord(struct sun8i_mixer *mixer,
>> +				     int layer, struct drm_plane *plane)
>> +{
>> +	struct drm_plane_state *state = plane->state;
>> +	struct drm_framebuffer *fb = state->fb;
>> +	/* Currently the first UI channel is used */
>> +	int chan = mixer->cfg->vi_num;
>> +
>> +	DRM_DEBUG_DRIVER("Updating layer %d\n", layer);
>> +
>> +	if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
>> +		DRM_DEBUG_DRIVER("Primary layer, updating global size W: %u H: 
>> %u\n",
>> +				 state->crtc_w, state->crtc_h);
>> +		regmap_write(mixer->engine.regs, SUN8I_MIXER_GLOBAL_SIZE,
>> +			     SUN8I_MIXER_SIZE(state->crtc_w,
>> +					      state->crtc_h));
>> +		DRM_DEBUG_DRIVER("Updating blender size\n");
>> +		regmap_write(mixer->engine.regs,
>> +			     SUN8I_MIXER_BLEND_ATTR_INSIZE(0),
>> +			     SUN8I_MIXER_SIZE(state->crtc_w,
>> +					      state->crtc_h));
>> +		regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_OUTSIZE,
>> +			     SUN8I_MIXER_SIZE(state->crtc_w,
>> +					      state->crtc_h));
>> +		DRM_DEBUG_DRIVER("Updating channel size\n");
>> +		regmap_write(mixer->engine.regs,
>> +			     SUN8I_MIXER_CHAN_UI_OVL_SIZE(chan),
>> +			     SUN8I_MIXER_SIZE(state->crtc_w,
>> +					      state->crtc_h));
>> +	}
>> +
>> +	/* Set the line width */
>> +	DRM_DEBUG_DRIVER("Layer line width: %d bytes\n", fb->pitches[0]);
>> +	regmap_write(mixer->engine.regs,
>> +		     SUN8I_MIXER_CHAN_UI_LAYER_PITCH(chan, layer),
>> +		     fb->pitches[0]);
>> +
>> +	/* Set height and width */
>> +	DRM_DEBUG_DRIVER("Layer size W: %u H: %u\n",
>> +			 state->crtc_w, state->crtc_h);
>> +	regmap_write(mixer->engine.regs,
>> +		     SUN8I_MIXER_CHAN_UI_LAYER_SIZE(chan, layer),
>> +		     SUN8I_MIXER_SIZE(state->crtc_w, state->crtc_h));
>> +
>> +	/* Set base coordinates */
>> +	DRM_DEBUG_DRIVER("Layer coordinates X: %d Y: %d\n",
>> +			 state->crtc_x, state->crtc_y);
>> +	regmap_write(mixer->engine.regs,
>> +		     SUN8I_MIXER_CHAN_UI_LAYER_COORD(chan, layer),
>> +		     SUN8I_MIXER_COORD(state->crtc_x, state->crtc_y));
> 
> X and Y are fixed point numbers. You want to keep only the higher 16
> bits there.

Do you mean "lower 16 bits"? Thus should I (x & 0xffff) or ((u16)x) ?

P.S. The negative coordinates are broken, how should I deal with it? or
is the coordinates promised to be not negative?

> 
>> +
>> +	return 0;
>> +}
>> +
>> +int sun8i_mixer_update_layer_formats(struct sun8i_mixer *mixer,
>> +				       int layer, struct drm_plane *plane)
>> +{
>> +	struct drm_plane_state *state = plane->state;
>> +	struct drm_framebuffer *fb = state->fb;
>> +	bool interlaced = false;
>> +	u32 val;
>> +	/* Currently the first UI channel is used */
>> +	int chan = mixer->cfg->vi_num;
>> +	int ret;
>> +
>> +	if (plane->state->crtc)
>> +		interlaced = plane->state->crtc->state->adjusted_mode.flags
>> +			& DRM_MODE_FLAG_INTERLACE;
>> +
>> +	regmap_update_bits(mixer->engine.regs, SUN8I_MIXER_BLEND_OUTCTL,
>> +			   SUN8I_MIXER_BLEND_OUTCTL_INTERLACED,
>> +			   interlaced ?
>> +			   SUN8I_MIXER_BLEND_OUTCTL_INTERLACED : 0);
>> +
>> +	DRM_DEBUG_DRIVER("Switching display mixer interlaced mode %s\n",
>> +			 interlaced ? "on" : "off");
>> +
>> +	ret = sun8i_mixer_drm_format_to_layer(plane, fb->format->format,
>> +						&val);
>> +	if (ret) {
>> +		DRM_DEBUG_DRIVER("Invalid format\n");
>> +		return ret;
>> +	}
>> +
>> +	regmap_update_bits(mixer->engine.regs,
>> +			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR(chan, layer),
>> +			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR_FBFMT_MASK, val);
>> +
>> +	return 0;
>> +}
>> +
>> +int sun8i_mixer_update_layer_buffer(struct sun8i_mixer *mixer,
>> +				      int layer, struct drm_plane *plane)
>> +{
>> +	struct drm_plane_state *state = plane->state;
>> +	struct drm_framebuffer *fb = state->fb;
>> +	struct drm_gem_cma_object *gem;
>> +	dma_addr_t paddr;
>> +	/* Currently the first UI channel is used */
>> +	int chan = mixer->cfg->vi_num;
>> +	int bpp;
>> +
>> +	/* Get the physical address of the buffer in memory */
>> +	gem = drm_fb_cma_get_gem_obj(fb, 0);
>> +
>> +	DRM_DEBUG_DRIVER("Using GEM @ %pad\n", &gem->paddr);
>> +
>> +	/* Compute the start of the displayed memory */
>> +	bpp = fb->format->cpp[0];
>> +	paddr = gem->paddr + fb->offsets[0];
>> +	paddr += (state->src_x >> 16) * bpp;
>> +	paddr += (state->src_y >> 16) * fb->pitches[0];
>> +
>> +	DRM_DEBUG_DRIVER("Setting buffer address to %pad\n", &paddr);
>> +
>> +	regmap_write(mixer->engine.regs,
>> +		     SUN8I_MIXER_CHAN_UI_LAYER_TOP_LADDR(chan, layer),
>> +		     lower_32_bits(paddr));
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct sunxi_engine_ops sun8i_engine_ops = {
>> +	.commit		= sun8i_mixer_commit,
>> +	.layers_init	= sun8i_layers_init,
>> +};
>> +
>> +static struct regmap_config sun8i_mixer_regmap_config = {
>> +	.reg_bits	= 32,
>> +	.val_bits	= 32,
>> +	.reg_stride	= 4,
>> +	.max_register	= 0xbfffc, /* guessed */
>> +};
>> +
>> +static int sun8i_mixer_bind(struct device *dev, struct device 
>> *master,
>> +			      void *data)
>> +{
>> +	struct platform_device *pdev = to_platform_device(dev);
>> +	struct drm_device *drm = data;
>> +	struct sun4i_drv *drv = drm->dev_private;
>> +	struct sun8i_mixer *mixer;
>> +	struct resource *res;
>> +	void __iomem *regs;
>> +	int i, ret;
>> +
>> +	/*
>> +	 * The mixer uses single 32-bit register to store memory
>> +	 * addresses, so that it cannot deal with 64-bit memory
>> +	 * addresses.
>> +	 * Restrict the DMA mask so that the mixer won't be
>> +	 * allocated some memory that is too high.
>> +	 */
>> +	ret = dma_set_mask(dev, DMA_BIT_MASK(32));
>> +	if (ret) {
>> +		dev_err(dev, "Cannot do 32-bit DMA.\n");
>> +		return ret;
>> +	}
>> +
>> +	mixer = devm_kzalloc(dev, sizeof(*mixer), GFP_KERNEL);
>> +	if (!mixer)
>> +		return -ENOMEM;
>> +	dev_set_drvdata(dev, mixer);
>> +	mixer->engine.ops = &sun8i_engine_ops;
>> +	mixer->engine.node = dev->of_node;
>> +
>> +	mixer->cfg = of_device_get_match_data(dev);
>> +	if (!mixer->cfg)
>> +		return -EINVAL;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	regs = devm_ioremap_resource(dev, res);
>> +	if (IS_ERR(regs))
>> +		return PTR_ERR(regs);
>> +
>> +	mixer->engine.regs = devm_regmap_init_mmio(dev, regs,
>> +						   &sun8i_mixer_regmap_config);
>> +	if (IS_ERR(mixer->engine.regs)) {
>> +		dev_err(dev, "Couldn't create the mixer regmap\n");
>> +		return PTR_ERR(mixer->engine.regs);
>> +	}
>> +
>> +	mixer->reset = devm_reset_control_get(dev, NULL);
>> +	if (IS_ERR(mixer->reset)) {
>> +		dev_err(dev, "Couldn't get our reset line\n");
>> +		return PTR_ERR(mixer->reset);
>> +	}
>> +
>> +	ret = reset_control_deassert(mixer->reset);
>> +	if (ret) {
>> +		dev_err(dev, "Couldn't deassert our reset line\n");
>> +		return ret;
>> +	}
>> +
>> +	mixer->bus_clk = devm_clk_get(dev, "bus");
>> +	if (IS_ERR(mixer->bus_clk)) {
>> +		dev_err(dev, "Couldn't get the mixer bus clock\n");
>> +		ret = PTR_ERR(mixer->bus_clk);
>> +		goto err_assert_reset;
>> +	}
>> +	clk_prepare_enable(mixer->bus_clk);
>> +
>> +	mixer->mod_clk = devm_clk_get(dev, "mod");
>> +	if (IS_ERR(mixer->mod_clk)) {
>> +		dev_err(dev, "Couldn't get the mixer module clock\n");
>> +		ret = PTR_ERR(mixer->mod_clk);
>> +		goto err_disable_bus_clk;
>> +	}
>> +	clk_prepare_enable(mixer->mod_clk);
>> +
>> +	list_add_tail(&mixer->engine.list, &drv->engine_list);
> 
> You didn't call INIT_LIST_HEAD on that list.
> 
>> +
>> +	/* Reset the registers */
>> +	for (i = 0x0; i < 0x20000; i += 4)
>> +		regmap_write(mixer->engine.regs, i, 0);
>> +
>> +	/* Enable the mixer */
>> +	regmap_write(mixer->engine.regs, SUN8I_MIXER_GLOBAL_CTL,
>> +		     SUN8I_MIXER_GLOBAL_CTL_RT_EN);
>> +
>> +	/* Initialize blender */
>> +	regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_FCOLOR_CTL,
>> +		     SUN8I_MIXER_BLEND_FCOLOR_CTL_DEF);
>> +	regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_PREMULTIPLY,
>> +		     SUN8I_MIXER_BLEND_PREMULTIPLY_DEF);
>> +	regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_BKCOLOR,
>> +		     SUN8I_MIXER_BLEND_BKCOLOR_DEF);
>> +	regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_MODE(0),
>> +		     SUN8I_MIXER_BLEND_MODE_DEF);
>> +	regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_CK_CTL,
>> +		     SUN8I_MIXER_BLEND_CK_CTL_DEF);
>> +
>> +	regmap_write(mixer->engine.regs,
>> +		     SUN8I_MIXER_BLEND_ATTR_FCOLOR(0),
>> +		     SUN8I_MIXER_BLEND_ATTR_FCOLOR_DEF);
>> +
>> +	/* Select the first UI channel */
>> +	DRM_DEBUG_DRIVER("Selecting channel %d (first UI channel)\n",
>> +			 mixer->cfg->vi_num);
>> +	regmap_write(mixer->engine.regs, SUN8I_MIXER_BLEND_ROUTE,
>> +		     mixer->cfg->vi_num);
>> +
>> +	return 0;
>> +
>> +	clk_disable_unprepare(mixer->mod_clk);
> 
> This line cannot be reached.
> 
> Maxime

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