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From:   Leonard Crestez <leonard.crestez@nxp.com>
To:     Lucas Stach <l.stach@pengutronix.de>,
        Shawn Guo <shawnguo@kernel.org>, Marek Vasut <marex@denx.de>,
        Fabio Estevam <fabio.estevam@nxp.com>,
        David Airlie <airlied@linux.ie>
Cc:     Robert Chiras <robert.chiras@nxp.com>,
        dri-devel@lists.freedesktop.org,
        Marco Franchi <marco.franchi@nxp.com>,
        Stefan Agner <stefan@agner.ch>,
        Mirela Rabulea <mirela.rabulea@nxp.com>,
        Laurentiu Palcu <laurentiu.palcu@nxp.com>,
        Dong Aisheng <aisheng.dong@nxp.com>, linux-imx@nxp.com,
        kernel@pengutronix.de, linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] drm/mxsfb: Fix runtime PM for unpowering lcdif block
Date:   Tue,  5 Jun 2018 20:11:05 +0300
Message-Id: <cd4ddc544a27915cab58a218223723eb18525c21.1528218001.git.leonard.crestez@nxp.com>
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Adding imx6sl/sx lcdif nodes in a power domain currently does work, it
results in black/corrupted screens or hangs. While the driver does
enable runtime pm it does not deal correctly with the block being
unpowered.

Fix by adding pm_runtime_get/put_sync to mxsfb_pipe_enable/disable.

The mxsfb_plane_atomic_update function can get called before
mxsfb_pipe_enable while the block is not powered. When this happens the
write to LCDIF_NEXT_BUF is lost causing random corrupted pixels on
unblank.

Fix this by splitting the writing of gem->paddr to nextbuf into a
mxsfb_update_hw_next_buf functiona and also calling it from
mxsfb_crtc_mode_set_nofb.

Also add fields to mxsfb_drv to keep track of enabled/suspended states.

Signed-off-by: Robert Chiras <robert.chiras@nxp.com>
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>

---
 drivers/gpu/drm/mxsfb/mxsfb_crtc.c | 38 +++++++++++-----
 drivers/gpu/drm/mxsfb/mxsfb_drv.c  | 72 +++++++++++++++++++++++++++++-
 drivers/gpu/drm/mxsfb/mxsfb_drv.h  |  3 ++
 3 files changed, 100 insertions(+), 13 deletions(-)

This was initially written by Robert for imx8m but I tested it also
works on imx6sx/imx6sl to DISPMIX power domain.

Tested on imx6sl-evk and imx6sx-sdb with SEIKO 43WVF1G panel by
blanking and unblanking via sysfs and suspend/resume

Testing requires a modified config (to enable MXFSB_DRM):
CONFIG_DRM_MXSFB=y
CONFIG_DRM_PANEL_SEIKO_43WVF1G=y
CONFIG_FB_MXS=n

It also requires dts changes to enable the DISPMIX power domain.  The
dts changes might break drivers so this patch attempts to fix the lcdif
driver first.

Patch 2 is a RFC of imx6sl changes, imx6sx is a bit more complicated
and it also interacts with PCI.

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
index 0abe77675b76..cce2ec1c80ae 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
@@ -194,10 +194,25 @@ static int mxsfb_reset_block(void __iomem *reset_addr)
 		return ret;
 
 	return clear_poll_bit(reset_addr, MODULE_CLKGATE);
 }
 
+static void mxsfb_update_hw_next_buf(struct mxsfb_drm_private *mxsfb)
+{
+	struct drm_framebuffer *fb = mxsfb->pipe.plane.state->fb;
+	struct drm_gem_cma_object *gem;
+
+	if (!fb)
+		return;
+
+	gem = drm_fb_cma_get_gem_obj(fb, 0);
+	if (!gem)
+		return;
+
+	writel(gem->paddr, mxsfb->base + mxsfb->devdata->next_buf);
+}
+
 static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb)
 {
 	struct drm_display_mode *m = &mxsfb->pipe.crtc.state->adjusted_mode;
 	const u32 bus_flags = mxsfb->connector.display_info.bus_flags;
 	u32 vdctrl0, vsync_pulse_len, hsync_pulse_len;
@@ -268,35 +283,41 @@ static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb)
 	       mxsfb->base + LCDC_VDCTRL3);
 
 	writel(SET_DOTCLK_H_VALID_DATA_CNT(m->hdisplay),
 	       mxsfb->base + LCDC_VDCTRL4);
 
+	mxsfb_update_hw_next_buf(mxsfb);
 	mxsfb_disable_axi_clk(mxsfb);
 }
 
 void mxsfb_crtc_enable(struct mxsfb_drm_private *mxsfb)
 {
+	if (mxsfb->enabled)
+		return;
+
 	mxsfb_crtc_mode_set_nofb(mxsfb);
 	mxsfb_enable_controller(mxsfb);
+
+	mxsfb->enabled = true;
 }
 
 void mxsfb_crtc_disable(struct mxsfb_drm_private *mxsfb)
 {
+	if (!mxsfb->enabled)
+		return;
+
 	mxsfb_disable_controller(mxsfb);
+
+	mxsfb->enabled = false;
 }
 
 void mxsfb_plane_atomic_update(struct mxsfb_drm_private *mxsfb,
 			       struct drm_plane_state *state)
 {
 	struct drm_simple_display_pipe *pipe = &mxsfb->pipe;
 	struct drm_crtc *crtc = &pipe->crtc;
-	struct drm_framebuffer *fb = pipe->plane.state->fb;
 	struct drm_pending_vblank_event *event;
-	struct drm_gem_cma_object *gem;
-
-	if (!crtc)
-		return;
 
 	spin_lock_irq(&crtc->dev->event_lock);
 	event = crtc->state->event;
 	if (event) {
 		crtc->state->event = NULL;
@@ -307,14 +328,9 @@ void mxsfb_plane_atomic_update(struct mxsfb_drm_private *mxsfb,
 			drm_crtc_send_vblank_event(crtc, event);
 		}
 	}
 	spin_unlock_irq(&crtc->dev->event_lock);
 
-	if (!fb)
-		return;
-
-	gem = drm_fb_cma_get_gem_obj(fb, 0);
-
 	mxsfb_enable_axi_clk(mxsfb);
-	writel(gem->paddr, mxsfb->base + mxsfb->devdata->next_buf);
+	mxsfb_update_hw_next_buf(mxsfb);
 	mxsfb_disable_axi_clk(mxsfb);
 }
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
index 5cae8db9dcd4..c889cac2e275 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
@@ -100,23 +100,27 @@ static const struct drm_mode_config_funcs mxsfb_mode_config_funcs = {
 
 static void mxsfb_pipe_enable(struct drm_simple_display_pipe *pipe,
 			      struct drm_crtc_state *crtc_state)
 {
 	struct mxsfb_drm_private *mxsfb = drm_pipe_to_mxsfb_drm_private(pipe);
+	struct drm_device *drm = pipe->plane.dev;
 
+	pm_runtime_get_sync(drm->dev);
 	drm_panel_prepare(mxsfb->panel);
 	mxsfb_crtc_enable(mxsfb);
 	drm_panel_enable(mxsfb->panel);
 }
 
 static void mxsfb_pipe_disable(struct drm_simple_display_pipe *pipe)
 {
 	struct mxsfb_drm_private *mxsfb = drm_pipe_to_mxsfb_drm_private(pipe);
+	struct drm_device *drm = pipe->plane.dev;
 
 	drm_panel_disable(mxsfb->panel);
 	mxsfb_crtc_disable(mxsfb);
 	drm_panel_unprepare(mxsfb->panel);
+	pm_runtime_put_sync(drm->dev);
 }
 
 static void mxsfb_pipe_update(struct drm_simple_display_pipe *pipe,
 			      struct drm_plane_state *plane_state)
 {
@@ -175,10 +179,11 @@ static int mxsfb_load(struct drm_device *drm, unsigned long flags)
 	if (!mxsfb)
 		return -ENOMEM;
 
 	drm->dev_private = mxsfb;
 	mxsfb->devdata = &mxsfb_devdata[pdev->id_entry->driver_data];
+	platform_set_drvdata(pdev, drm);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	mxsfb->base = devm_ioremap_resource(drm->dev, res);
 	if (IS_ERR(mxsfb->base))
 		return PTR_ERR(mxsfb->base);
@@ -256,12 +261,10 @@ static int mxsfb_load(struct drm_device *drm, unsigned long flags)
 		mxsfb->fbdev = NULL;
 		dev_err(drm->dev, "Failed to init FB CMA area\n");
 		goto err_cma;
 	}
 
-	platform_set_drvdata(pdev, drm);
-
 	drm_helper_hpd_irq_event(drm);
 
 	return 0;
 
 err_cma:
@@ -417,17 +420,82 @@ static int mxsfb_remove(struct platform_device *pdev)
 	drm_dev_unref(drm);
 
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int mxsfb_runtime_suspend(struct device *dev)
+{
+	struct drm_device *drm = dev_get_drvdata(dev);
+	struct mxsfb_drm_private *mxsfb = drm->dev_private;
+
+	if (!drm->registered)
+		return 0;
+
+	if (mxsfb->enabled) {
+		mxsfb_crtc_disable(mxsfb);
+		mxsfb->suspended = true;
+	}
+
+	return 0;
+}
+
+static int mxsfb_runtime_resume(struct device *dev)
+{
+	struct drm_device *drm = dev_get_drvdata(dev);
+	struct mxsfb_drm_private *mxsfb = drm->dev_private;
+
+	if (!drm->registered || !mxsfb->suspended)
+		return 0;
+
+	mxsfb_crtc_enable(mxsfb);
+	mxsfb->suspended = false;
+
+	return 0;
+}
+
+static int mxsfb_suspend(struct device *dev)
+{
+	struct drm_device *drm = dev_get_drvdata(dev);
+	struct mxsfb_drm_private *mxsfb = drm->dev_private;
+
+	if (mxsfb->enabled) {
+		mxsfb_crtc_disable(mxsfb);
+		mxsfb->suspended = true;
+	}
+
+	return 0;
+}
+
+static int mxsfb_resume(struct device *dev)
+{
+	struct drm_device *drm = dev_get_drvdata(dev);
+	struct mxsfb_drm_private *mxsfb = drm->dev_private;
+
+	if (!mxsfb->suspended)
+		return 0;
+
+	mxsfb_crtc_enable(mxsfb);
+	mxsfb->suspended = false;
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops mxsfb_pm_ops = {
+	SET_RUNTIME_PM_OPS(mxsfb_runtime_suspend, mxsfb_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(mxsfb_suspend, mxsfb_resume)
+};
+
 static struct platform_driver mxsfb_platform_driver = {
 	.probe		= mxsfb_probe,
 	.remove		= mxsfb_remove,
 	.id_table	= mxsfb_devtype,
 	.driver	= {
 		.name		= "mxsfb",
 		.of_match_table	= mxsfb_dt_ids,
+		.pm = &mxsfb_pm_ops,
 	},
 };
 
 module_platform_driver(mxsfb_platform_driver);
 
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.h b/drivers/gpu/drm/mxsfb/mxsfb_drv.h
index 5d0883fc805b..d8ef4a053f0e 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.h
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.h
@@ -36,10 +36,13 @@ struct mxsfb_drm_private {
 
 	struct drm_simple_display_pipe	pipe;
 	struct drm_connector		connector;
 	struct drm_panel		*panel;
 	struct drm_fbdev_cma		*fbdev;
+
+	bool                            enabled;
+	bool                            suspended;
 };
 
 int mxsfb_setup_crtc(struct drm_device *dev);
 int mxsfb_create_output(struct drm_device *dev);
 
-- 
2.17.0