[6/6] drm: mali-dp: Add writeback connector

Message ID 1480092544-1725-7-git-send-email-brian.starkey@arm.com (mailing list archive)
State Not Applicable, archived
Headers

Commit Message

Brian Starkey Nov. 25, 2016, 4:49 p.m. UTC
  Mali-DP has a memory writeback engine which can be used to write the
composition result to a memory buffer. Expose this functionality as a
DRM writeback connector on supported hardware.

Changes since v1:
 Daniel Vetter:
 - Don't require a modeset when writeback routing changes
 - Make writeback connector always disconnected

Changes since v2:
 - Rebase onto new drm_writeback_connector
 - Add reset callback, allocating subclassed state
 Daniel Vetter:
 - Squash out-fence support into this commit
 Gustavo Padovan:
 - Don't signal fence directly from driver (and drop malidp_mw_job)

Signed-off-by: Brian Starkey <brian.starkey@arm.com>
---
 drivers/gpu/drm/arm/Makefile      |    1 +
 drivers/gpu/drm/arm/malidp_crtc.c |   21 +++
 drivers/gpu/drm/arm/malidp_drv.c  |   25 +++-
 drivers/gpu/drm/arm/malidp_drv.h  |    3 +
 drivers/gpu/drm/arm/malidp_hw.c   |    7 +-
 drivers/gpu/drm/arm/malidp_mw.c   |  278 +++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/arm/malidp_mw.h   |   18 +++
 7 files changed, 348 insertions(+), 5 deletions(-)
 create mode 100644 drivers/gpu/drm/arm/malidp_mw.c
 create mode 100644 drivers/gpu/drm/arm/malidp_mw.h
  

Comments

Boris BREZILLON April 14, 2017, 9:47 a.m. UTC | #1
On Fri, 25 Nov 2016 16:49:04 +0000
Brian Starkey <brian.starkey@arm.com> wrote:

> +static int
> +malidp_mw_encoder_atomic_check(struct drm_encoder *encoder,
> +			       struct drm_crtc_state *crtc_state,
> +			       struct drm_connector_state *conn_state)
> +{
> +	struct malidp_mw_connector_state *mw_state = to_mw_state(conn_state);
> +	struct malidp_drm *malidp = encoder->dev->dev_private;
> +	struct drm_framebuffer *fb;
> +	int i, n_planes;
> +
> +	if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
> +		return 0;
> +
> +	fb = conn_state->writeback_job->fb;
> +	if ((fb->width != crtc_state->mode.hdisplay) ||
> +	    (fb->height != crtc_state->mode.vdisplay)) {
> +		DRM_DEBUG_KMS("Invalid framebuffer size %ux%u\n",
> +				fb->width, fb->height);
> +		return -EINVAL;
> +	}

These checks look pretty generic to me. Shouldn't we have a default
helper doing that?

> +
> +	mw_state->format =
> +		malidp_hw_get_format_id(&malidp->dev->map, SE_MEMWRITE,
> +					fb->pixel_format);
> +	if (mw_state->format == MALIDP_INVALID_FORMAT_ID) {

Same goes here. By adding a format_types table similar to what is
exposed in drm_plane [1], we could do this check in the core. The only
thing left to the driver is the 4CC -> driver-specific-id conversion.

> +		struct drm_format_name_buf format_name;
> +
> +		DRM_DEBUG_KMS("Invalid pixel format %s\n",
> +			      drm_get_format_name(fb->pixel_format, &format_name));
> +		return -EINVAL;
> +	}
> +
> +	n_planes = drm_format_num_planes(fb->pixel_format);
> +	for (i = 0; i < n_planes; i++) {
> +		struct drm_gem_cma_object *obj = drm_fb_cma_get_gem_obj(fb, i);
> +		if (!malidp_hw_pitch_valid(malidp->dev, fb->pitches[i])) {
> +			DRM_DEBUG_KMS("Invalid pitch %u for plane %d\n",
> +				      fb->pitches[i], i);
> +			return -EINVAL;
> +		}
> +		mw_state->pitches[i] = fb->pitches[i];
> +		mw_state->addrs[i] = obj->paddr + fb->offsets[i];
> +	}
> +	mw_state->n_planes = n_planes;
> +
> +	return 0;
> +}


[1]http://lxr.free-electrons.com/source/include/drm/drm_plane.h#L482
  
Brian Starkey April 18, 2017, 5:35 p.m. UTC | #2
On Fri, Apr 14, 2017 at 11:47:00AM +0200, Boris Brezillon wrote:
>On Fri, 25 Nov 2016 16:49:04 +0000
>Brian Starkey <brian.starkey@arm.com> wrote:
>
>> +static int
>> +malidp_mw_encoder_atomic_check(struct drm_encoder *encoder,
>> +			       struct drm_crtc_state *crtc_state,
>> +			       struct drm_connector_state *conn_state)
>> +{
>> +	struct malidp_mw_connector_state *mw_state = to_mw_state(conn_state);
>> +	struct malidp_drm *malidp = encoder->dev->dev_private;
>> +	struct drm_framebuffer *fb;
>> +	int i, n_planes;
>> +
>> +	if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
>> +		return 0;
>> +
>> +	fb = conn_state->writeback_job->fb;
>> +	if ((fb->width != crtc_state->mode.hdisplay) ||
>> +	    (fb->height != crtc_state->mode.vdisplay)) {
>> +		DRM_DEBUG_KMS("Invalid framebuffer size %ux%u\n",
>> +				fb->width, fb->height);
>> +		return -EINVAL;
>> +	}
>
>These checks look pretty generic to me. Shouldn't we have a default
>helper doing that?
>

Yeah makes sense. These should be common to everyone until
cropping/scaling support is added.

>> +
>> +	mw_state->format =
>> +		malidp_hw_get_format_id(&malidp->dev->map, SE_MEMWRITE,
>> +					fb->pixel_format);
>> +	if (mw_state->format == MALIDP_INVALID_FORMAT_ID) {
>
>Same goes here. By adding a format_types table similar to what is
>exposed in drm_plane [1], we could do this check in the core. The only
>thing left to the driver is the 4CC -> driver-specific-id conversion.
>

Yeah could do, but given our driver requires us to run through the
whole table to get the HW ID anyway it seemed like totally wasted
effort to do the same thing in the core.

It's probably a negligible overhead, but it's also unnecessary for
100% of the current writeback implementations ;-)

If a different driver is implemented such that the HW ID lookup isn't
an exhaustive list search then we could add a helper for them to use
which checks the blob.

Cheers,
-Brian

>> +		struct drm_format_name_buf format_name;
>> +
>> +		DRM_DEBUG_KMS("Invalid pixel format %s\n",
>> +			      drm_get_format_name(fb->pixel_format, &format_name));
>> +		return -EINVAL;
>> +	}
>> +
>> +	n_planes = drm_format_num_planes(fb->pixel_format);
>> +	for (i = 0; i < n_planes; i++) {
>> +		struct drm_gem_cma_object *obj = drm_fb_cma_get_gem_obj(fb, i);
>> +		if (!malidp_hw_pitch_valid(malidp->dev, fb->pitches[i])) {
>> +			DRM_DEBUG_KMS("Invalid pitch %u for plane %d\n",
>> +				      fb->pitches[i], i);
>> +			return -EINVAL;
>> +		}
>> +		mw_state->pitches[i] = fb->pitches[i];
>> +		mw_state->addrs[i] = obj->paddr + fb->offsets[i];
>> +	}
>> +	mw_state->n_planes = n_planes;
>> +
>> +	return 0;
>> +}
>
>
>[1]http://lxr.free-electrons.com/source/include/drm/drm_plane.h#L482
  

Patch

diff --git a/drivers/gpu/drm/arm/Makefile b/drivers/gpu/drm/arm/Makefile
index bb8b158..3bf31d1 100644
--- a/drivers/gpu/drm/arm/Makefile
+++ b/drivers/gpu/drm/arm/Makefile
@@ -1,4 +1,5 @@ 
 hdlcd-y := hdlcd_drv.o hdlcd_crtc.o
 obj-$(CONFIG_DRM_HDLCD)	+= hdlcd.o
 mali-dp-y := malidp_drv.o malidp_hw.o malidp_planes.o malidp_crtc.o
+mali-dp-y += malidp_mw.o
 obj-$(CONFIG_DRM_MALI_DISPLAY)	+= mali-dp.o
diff --git a/drivers/gpu/drm/arm/malidp_crtc.c b/drivers/gpu/drm/arm/malidp_crtc.c
index 08e6a71..5413a5a 100644
--- a/drivers/gpu/drm/arm/malidp_crtc.c
+++ b/drivers/gpu/drm/arm/malidp_crtc.c
@@ -68,6 +68,18 @@  static void malidp_crtc_enable(struct drm_crtc *crtc)
 	clk_set_rate(hwdev->pxlclk, crtc->state->adjusted_mode.crtc_clock * 1000);
 
 	hwdev->modeset(hwdev, &vm);
+	/*
+	 * We should always disable the memory write when leaving config mode,
+	 * otherwise the hardware will start writing right away - possibly with
+	 * a stale config, and definitely before we've had a chance to configure
+	 * the planes.
+	 * If the memory write needs to be enabled, that will get taken care
+	 * of later during the atomic commit
+	 */
+	if (hwdev->disable_memwrite) {
+		DRM_DEV_DEBUG_DRIVER(crtc->dev->dev, "Disable memwrite\n");
+		hwdev->disable_memwrite(hwdev);
+	}
 	hwdev->leave_config_mode(hwdev);
 	drm_crtc_vblank_on(crtc);
 }
@@ -157,6 +169,15 @@  static int malidp_crtc_atomic_check(struct drm_crtc *crtc,
 		}
 	}
 
+	/* If only the writeback routing has changed, we don't need a modeset */
+	if (state->connectors_changed) {
+		u32 old_mask = crtc->state->connector_mask;
+		u32 new_mask = state->connector_mask;
+		if ((old_mask ^ new_mask) ==
+		    (1 << drm_connector_index(&malidp->mw_connector.base)))
+			state->connectors_changed = false;
+	}
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/arm/malidp_drv.c b/drivers/gpu/drm/arm/malidp_drv.c
index 32f746e..2d0465b 100644
--- a/drivers/gpu/drm/arm/malidp_drv.c
+++ b/drivers/gpu/drm/arm/malidp_drv.c
@@ -28,6 +28,7 @@ 
 #include <drm/drm_of.h>
 
 #include "malidp_drv.h"
+#include "malidp_mw.h"
 #include "malidp_regs.h"
 #include "malidp_hw.h"
 
@@ -92,6 +93,14 @@  static void malidp_atomic_commit_tail(struct drm_atomic_state *state)
 
 	drm_atomic_helper_commit_modeset_disables(drm, state);
 	drm_atomic_helper_commit_modeset_enables(drm, state);
+
+	/*
+	 * The order here is important. We must configure memory-write after
+	 * the CRTC is already enabled, so that its configuration update is
+	 * gated on the next CVAL.
+	 */
+	malidp_mw_atomic_commit(drm, state);
+
 	drm_atomic_helper_commit_planes(drm, state, 0);
 
 	malidp_atomic_commit_hw_done(state);
@@ -147,12 +156,20 @@  static int malidp_init(struct drm_device *drm)
 	drm->mode_config.helper_private = &malidp_mode_config_helpers;
 
 	ret = malidp_crtc_init(drm);
-	if (ret) {
-		drm_mode_config_cleanup(drm);
-		return ret;
-	}
+	if (ret)
+		goto crtc_fail;
+
+	ret = malidp_mw_connector_init(drm);
+	if (ret)
+		goto mw_fail;
 
 	return 0;
+
+mw_fail:
+	malidp_de_planes_destroy(drm);
+crtc_fail:
+	drm_mode_config_cleanup(drm);
+	return ret;
 }
 
 static void malidp_fini(struct drm_device *drm)
diff --git a/drivers/gpu/drm/arm/malidp_drv.h b/drivers/gpu/drm/arm/malidp_drv.h
index 9fc8a2e..8abfa8a 100644
--- a/drivers/gpu/drm/arm/malidp_drv.h
+++ b/drivers/gpu/drm/arm/malidp_drv.h
@@ -13,6 +13,7 @@ 
 #ifndef __MALIDP_DRV_H__
 #define __MALIDP_DRV_H__
 
+#include <drm/drm_writeback.h>
 #include <linux/mutex.h>
 #include <linux/wait.h>
 #include "malidp_hw.h"
@@ -22,6 +23,8 @@  struct malidp_drm {
 	struct drm_fbdev_cma *fbdev;
 	struct list_head event_list;
 	struct drm_crtc crtc;
+	struct drm_encoder mw_encoder;
+	struct drm_writeback_connector mw_connector;
 	wait_queue_head_t wq;
 	atomic_t config_valid;
 };
diff --git a/drivers/gpu/drm/arm/malidp_hw.c b/drivers/gpu/drm/arm/malidp_hw.c
index be17631..1fee5ee 100644
--- a/drivers/gpu/drm/arm/malidp_hw.c
+++ b/drivers/gpu/drm/arm/malidp_hw.c
@@ -20,6 +20,7 @@ 
 
 #include "malidp_drv.h"
 #include "malidp_hw.h"
+#include "malidp_mw.h"
 
 static const struct malidp_format_id malidp500_de_formats[] = {
 	/*    fourcc,   layers supporting the format,     internal id  */
@@ -543,6 +544,7 @@  static int malidp650_query_hw(struct malidp_hw_device *hwdev)
 			.se_irq_map = {
 				.irq_mask = MALIDP550_SE_IRQ_EOW |
 					    MALIDP550_SE_IRQ_AXI_ERR,
+				.vsync_irq = MALIDP550_SE_IRQ_EOW,
 			},
 			.dc_irq_map = {
 				.irq_mask = MALIDP550_DC_IRQ_CONF_VALID |
@@ -684,6 +686,7 @@  static irqreturn_t malidp_se_irq(int irq, void *arg)
 	struct drm_device *drm = arg;
 	struct malidp_drm *malidp = drm->dev_private;
 	struct malidp_hw_device *hwdev = malidp->dev;
+	const struct malidp_irq_map *se = &hwdev->map.se_irq_map;
 	u32 status, mask;
 
 	status = malidp_hw_read(hwdev, hwdev->map.se_base + MALIDP_REG_STATUS);
@@ -693,7 +696,9 @@  static irqreturn_t malidp_se_irq(int irq, void *arg)
 	mask = malidp_hw_read(hwdev, hwdev->map.se_base + MALIDP_REG_MASKIRQ);
 	status = malidp_hw_read(hwdev, hwdev->map.se_base + MALIDP_REG_STATUS);
 	status &= mask;
-	/* ToDo: status decoding and firing up of VSYNC and page flip events */
+
+	if (status & se->vsync_irq)
+		drm_writeback_signal_completion(&malidp->mw_connector, 0);
 
 	malidp_hw_clear_irq(hwdev, MALIDP_SE_BLOCK, status);
 
diff --git a/drivers/gpu/drm/arm/malidp_mw.c b/drivers/gpu/drm/arm/malidp_mw.c
new file mode 100644
index 0000000..40f1137
--- /dev/null
+++ b/drivers/gpu/drm/arm/malidp_mw.c
@@ -0,0 +1,278 @@ 
+/*
+ * (C) COPYRIGHT 2016 ARM Limited. All rights reserved.
+ * Author: Brian Starkey <brian.starkey@arm.com>
+ *
+ * This program is free software and is provided to you under the terms of the
+ * GNU General Public License version 2 as published by the Free Software
+ * Foundation, and any use by you of this program is subject to the terms
+ * of such GNU licence.
+ *
+ * ARM Mali DP Writeback connector implementation
+ */
+#include <drm/drm_atomic.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/drmP.h>
+#include <drm/drm_writeback.h>
+
+#include "malidp_drv.h"
+#include "malidp_hw.h"
+#include "malidp_mw.h"
+
+#define to_mw_state(_state) (struct malidp_mw_connector_state *)(_state)
+
+struct malidp_mw_connector_state {
+	struct drm_connector_state base;
+	dma_addr_t addrs[2];
+	s32 pitches[2];
+	u8 format;
+	u8 n_planes;
+};
+
+static int malidp_mw_connector_get_modes(struct drm_connector *connector)
+{
+	struct drm_device *dev = connector->dev;
+
+	return drm_add_modes_noedid(connector, dev->mode_config.max_width,
+				    dev->mode_config.max_height);
+}
+
+static enum drm_mode_status
+malidp_mw_connector_mode_valid(struct drm_connector *connector,
+			       struct drm_display_mode *mode)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_mode_config *mode_config = &dev->mode_config;
+	int w = mode->hdisplay, h = mode->vdisplay;
+
+	if ((w < mode_config->min_width) || (w > mode_config->max_width))
+		return MODE_BAD_HVALUE;
+
+	if ((h < mode_config->min_height) || (h > mode_config->max_height))
+		return MODE_BAD_VVALUE;
+
+	return MODE_OK;
+}
+
+const struct drm_connector_helper_funcs malidp_mw_connector_helper_funcs = {
+	.get_modes = malidp_mw_connector_get_modes,
+	.mode_valid = malidp_mw_connector_mode_valid,
+};
+
+static void malidp_mw_connector_reset(struct drm_connector *connector)
+{
+	struct malidp_mw_connector_state *mw_state =
+		kzalloc(sizeof(*mw_state), GFP_KERNEL);
+
+	if (connector->state)
+		__drm_atomic_helper_connector_destroy_state(connector->state);
+
+	kfree(connector->state);
+	__drm_atomic_helper_connector_reset(connector, &mw_state->base);
+}
+
+static enum drm_connector_status
+malidp_mw_connector_detect(struct drm_connector *connector, bool force)
+{
+	return connector_status_disconnected;
+}
+
+static void malidp_mw_connector_destroy(struct drm_connector *connector)
+{
+	drm_connector_cleanup(connector);
+}
+
+static struct drm_connector_state *
+malidp_mw_connector_duplicate_state(struct drm_connector *connector)
+{
+	struct malidp_mw_connector_state *mw_state;
+
+	if (WARN_ON(!connector->state))
+		return NULL;
+
+	mw_state = kzalloc(sizeof(*mw_state), GFP_KERNEL);
+	if (!mw_state)
+		return NULL;
+
+	/* No need to preserve any of our driver-local data */
+	__drm_atomic_helper_connector_duplicate_state(connector, &mw_state->base);
+
+	return &mw_state->base;
+}
+
+static const struct drm_connector_funcs malidp_mw_connector_funcs = {
+	.dpms = drm_atomic_helper_connector_dpms,
+	.reset = malidp_mw_connector_reset,
+	.detect = malidp_mw_connector_detect,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = malidp_mw_connector_destroy,
+	.atomic_duplicate_state = malidp_mw_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static int
+malidp_mw_encoder_atomic_check(struct drm_encoder *encoder,
+			       struct drm_crtc_state *crtc_state,
+			       struct drm_connector_state *conn_state)
+{
+	struct malidp_mw_connector_state *mw_state = to_mw_state(conn_state);
+	struct malidp_drm *malidp = encoder->dev->dev_private;
+	struct drm_framebuffer *fb;
+	int i, n_planes;
+
+	if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
+		return 0;
+
+	fb = conn_state->writeback_job->fb;
+	if ((fb->width != crtc_state->mode.hdisplay) ||
+	    (fb->height != crtc_state->mode.vdisplay)) {
+		DRM_DEBUG_KMS("Invalid framebuffer size %ux%u\n",
+				fb->width, fb->height);
+		return -EINVAL;
+	}
+
+	mw_state->format =
+		malidp_hw_get_format_id(&malidp->dev->map, SE_MEMWRITE,
+					fb->pixel_format);
+	if (mw_state->format == MALIDP_INVALID_FORMAT_ID) {
+		struct drm_format_name_buf format_name;
+
+		DRM_DEBUG_KMS("Invalid pixel format %s\n",
+			      drm_get_format_name(fb->pixel_format, &format_name));
+		return -EINVAL;
+	}
+
+	n_planes = drm_format_num_planes(fb->pixel_format);
+	for (i = 0; i < n_planes; i++) {
+		struct drm_gem_cma_object *obj = drm_fb_cma_get_gem_obj(fb, i);
+		if (!malidp_hw_pitch_valid(malidp->dev, fb->pitches[i])) {
+			DRM_DEBUG_KMS("Invalid pitch %u for plane %d\n",
+				      fb->pitches[i], i);
+			return -EINVAL;
+		}
+		mw_state->pitches[i] = fb->pitches[i];
+		mw_state->addrs[i] = obj->paddr + fb->offsets[i];
+	}
+	mw_state->n_planes = n_planes;
+
+	return 0;
+}
+
+static const struct drm_encoder_helper_funcs malidp_mw_encoder_helper_funcs = {
+	.atomic_check = malidp_mw_encoder_atomic_check,
+};
+
+static void malidp_mw_encoder_destroy(struct drm_encoder *encoder)
+{
+	drm_encoder_cleanup(encoder);
+}
+
+static const struct drm_encoder_funcs malidp_mw_encoder_funcs = {
+	.destroy = malidp_mw_encoder_destroy,
+};
+
+static u32 *get_writeback_formats(struct malidp_drm *malidp, int *n_formats)
+{
+	const struct malidp_hw_regmap *map = &malidp->dev->map;
+	u32 *formats;
+	int n, i;
+
+	formats = kcalloc(map->n_pixel_formats, sizeof(*formats),
+			  GFP_KERNEL);
+	if (!formats)
+		return NULL;
+
+	for (n = 0, i = 0;  i < map->n_pixel_formats; i++) {
+		if (map->pixel_formats[i].layer & SE_MEMWRITE)
+			formats[n++] = map->pixel_formats[i].format;
+	}
+
+	*n_formats = n;
+	return formats;
+}
+
+int malidp_mw_connector_init(struct drm_device *drm)
+{
+	struct malidp_drm *malidp = drm->dev_private;
+	u32 *formats;
+	int ret, n_formats;
+
+	if (!malidp->dev->enable_memwrite)
+		return 0;
+
+	drm_encoder_helper_add(&malidp->mw_encoder, &malidp_mw_encoder_helper_funcs);
+	malidp->mw_encoder.possible_crtcs = 1 << drm_crtc_index(&malidp->crtc);
+	ret = drm_encoder_init(drm, &malidp->mw_encoder, &malidp_mw_encoder_funcs,
+			       DRM_MODE_ENCODER_VIRTUAL, NULL);
+	if (ret)
+		return ret;
+
+	drm_connector_helper_add(&malidp->mw_connector.base,
+				 &malidp_mw_connector_helper_funcs);
+	malidp->mw_connector.base.interlace_allowed = 0;
+
+	formats = get_writeback_formats(malidp, &n_formats);
+	if (!formats) {
+		ret = -ENOMEM;
+		goto err_encoder;
+	}
+
+	ret = drm_writeback_connector_init(drm, &malidp->mw_connector,
+					   &malidp_mw_connector_funcs,
+					   formats, n_formats);
+	kfree(formats);
+	if (ret)
+		goto err_encoder;
+
+	ret = drm_mode_connector_attach_encoder(&malidp->mw_connector.base,
+						&malidp->mw_encoder);
+	if (ret)
+		goto err_connector;
+
+	return 0;
+
+err_connector:
+	drm_connector_cleanup(&malidp->mw_connector.base);
+err_encoder:
+	drm_encoder_cleanup(&malidp->mw_encoder);
+	return ret;
+}
+
+void malidp_mw_atomic_commit(struct drm_device *drm,
+			     struct drm_atomic_state *old_state)
+{
+	struct malidp_drm *malidp = drm->dev_private;
+	struct drm_writeback_connector *mw_conn = &malidp->mw_connector;
+	struct drm_connector_state *conn_state = mw_conn->base.state;
+	struct malidp_hw_device *hwdev = malidp->dev;
+	struct malidp_mw_connector_state *mw_state;
+
+	if (!conn_state)
+		return;
+
+	mw_state = to_mw_state(conn_state);
+
+	if (conn_state->writeback_job && conn_state->writeback_job->fb) {
+		struct drm_framebuffer *fb = conn_state->writeback_job->fb;
+
+		DRM_DEV_DEBUG_DRIVER(drm->dev,
+				     "Enable memwrite %ux%u:%d %pad fmt: %u\n",
+				     fb->width, fb->height,
+				     mw_state->pitches[0],
+				     &mw_state->addrs[0],
+				     mw_state->format);
+
+		drm_writeback_queue_job(mw_conn, conn_state->writeback_job);
+		conn_state->writeback_job = NULL;
+
+		hwdev->enable_memwrite(hwdev, mw_state->addrs,
+				       mw_state->pitches, mw_state->n_planes,
+				       fb->width, fb->height, mw_state->format);
+	} else {
+		DRM_DEV_DEBUG_DRIVER(drm->dev, "Disable memwrite\n");
+		hwdev->disable_memwrite(hwdev);
+	}
+}
diff --git a/drivers/gpu/drm/arm/malidp_mw.h b/drivers/gpu/drm/arm/malidp_mw.h
new file mode 100644
index 0000000..93477ea
--- /dev/null
+++ b/drivers/gpu/drm/arm/malidp_mw.h
@@ -0,0 +1,18 @@ 
+/*
+ * (C) COPYRIGHT 2016 ARM Limited. All rights reserved.
+ * Author: Brian Starkey <brian.starkey@arm.com>
+ *
+ * This program is free software and is provided to you under the terms of the
+ * GNU General Public License version 2 as published by the Free Software
+ * Foundation, and any use by you of this program is subject to the terms
+ * of such GNU licence.
+ *
+ */
+
+#ifndef __MALIDP_MW_H__
+#define __MALIDP_MW_H__
+
+int malidp_mw_connector_init(struct drm_device *drm);
+void malidp_mw_atomic_commit(struct drm_device *drm,
+			     struct drm_atomic_state *old_state);
+#endif