[PATCH 1/2] drm/mxsfb: Fix runtime PM for unpowering lcdif block

From: Leonard Crestez
Date: Tue Jun 05 2018 - 13:11:32 EST

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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@xxxxxxx>
Signed-off-by: Leonard Crestez <leonard.crestez@xxxxxxx>

---
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

Next message: Leonard Crestez: "[RFC 2/2] ARM: dts: imx6sl: Convert gpc to new bindings"
Previous message: Greg Kroah-Hartman: "[PATCH 4.9 22/61] arm64: Add hypervisor safe helper for checking constant capabilities"
Next in thread: Leonard Crestez: "[RFC 2/2] ARM: dts: imx6sl: Convert gpc to new bindings"
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