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

[Stefan Agner <stefan@agner.ch>]

On 05.06.2018 19:11, Leonard Crestez wrote:
> 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>

That patch seems to go in the right direction.

One comment below.

> 
> ---
>  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;

Is this state keeping really necessary?

--
Stefan

>  }
>  
>  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);