[PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[Matthias Schiffer]

The PIXCLK needs to be enabled in SCFG before accessing the DCU on LS1021A,
or the access will hang.

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
---
 drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
 drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 25 +++++++++++++++++++++++
 drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
 3 files changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig b/drivers/gpu/drm/fsl-dcu/Kconfig
index d7dd8ba90e3a..9e5a35e7c00c 100644
--- a/drivers/gpu/drm/fsl-dcu/Kconfig
+++ b/drivers/gpu/drm/fsl-dcu/Kconfig
@@ -8,6 +8,7 @@ config DRM_FSL_DCU
 	select DRM_PANEL
 	select REGMAP_MMIO
 	select VIDEOMODE_HELPERS
+	select MFD_SYSCON if SOC_LS1021A
 	help
 	  Choose this option if you have an Freescale DCU chipset.
 	  If M is selected the module will be called fsl-dcu-drm.
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
index abbc1ddbf27f..8a7556655581 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
@@ -51,6 +51,23 @@ static const struct regmap_config fsl_dcu_regmap_config = {
 	.volatile_reg = fsl_dcu_drm_is_volatile_reg,
 };
 
+static int fsl_dcu_scfg_config_ls1021a(struct device_node *np)
+{
+	struct regmap *scfg;
+
+	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
+	if (IS_ERR(scfg))
+		return PTR_ERR(scfg);
+
+	/*
+	 * For simplicity, enable the PIXCLK unconditionally. It might
+	 * be possible to disable the clock in PM or on unload as a future
+	 * improvement.
+	 */
+	return regmap_update_bits(scfg, SCFG_PIXCLKCR, SCFG_PIXCLKCR_PXCEN,
+				  SCFG_PIXCLKCR_PXCEN);
+}
+
 static void fsl_dcu_irq_uninstall(struct drm_device *dev)
 {
 	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
@@ -70,6 +87,14 @@ static int fsl_dcu_load(struct drm_device *dev, unsigned long flags)
 		return ret;
 	}
 
+	if (of_device_is_compatible(fsl_dev->np, "fsl,ls1021a-dcu")) {
+		ret = fsl_dcu_scfg_config_ls1021a(fsl_dev->np);
+		if (ret < 0) {
+			dev_err(dev->dev, "failed to enable pixclk\n");
+			goto done;
+		}
+	}
+
 	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
 	if (ret < 0) {
 		dev_err(dev->dev, "failed to initialize vblank\n");
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
index e2049a0e8a92..566396013c04 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
@@ -160,6 +160,9 @@
 #define FSL_DCU_ARGB4444		12
 #define FSL_DCU_YUV422			14
 
+#define SCFG_PIXCLKCR			0x28
+#define SCFG_PIXCLKCR_PXCEN		BIT(31)
+
 #define VF610_LAYER_REG_NUM		9
 #define LS1021A_LAYER_REG_NUM		10
 
-- 
2.17.1

[PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[Matthias Schiffer]

The PIXCLK needs to be enabled in SCFG before accessing the DCU on LS1021A,
or the access will hang.

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
---
 drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
 drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 25 +++++++++++++++++++++++
 drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
 3 files changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig b/drivers/gpu/drm/fsl-dcu/Kconfig
index d7dd8ba90e3a..9e5a35e7c00c 100644
--- a/drivers/gpu/drm/fsl-dcu/Kconfig
+++ b/drivers/gpu/drm/fsl-dcu/Kconfig
@@ -8,6 +8,7 @@ config DRM_FSL_DCU
 	select DRM_PANEL
 	select REGMAP_MMIO
 	select VIDEOMODE_HELPERS
+	select MFD_SYSCON if SOC_LS1021A
 	help
 	  Choose this option if you have an Freescale DCU chipset.
 	  If M is selected the module will be called fsl-dcu-drm.
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
index abbc1ddbf27f..8a7556655581 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
@@ -51,6 +51,23 @@ static const struct regmap_config fsl_dcu_regmap_config = {
 	.volatile_reg = fsl_dcu_drm_is_volatile_reg,
 };
 
+static int fsl_dcu_scfg_config_ls1021a(struct device_node *np)
+{
+	struct regmap *scfg;
+
+	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
+	if (IS_ERR(scfg))
+		return PTR_ERR(scfg);
+
+	/*
+	 * For simplicity, enable the PIXCLK unconditionally. It might
+	 * be possible to disable the clock in PM or on unload as a future
+	 * improvement.
+	 */
+	return regmap_update_bits(scfg, SCFG_PIXCLKCR, SCFG_PIXCLKCR_PXCEN,
+				  SCFG_PIXCLKCR_PXCEN);
+}
+
 static void fsl_dcu_irq_uninstall(struct drm_device *dev)
 {
 	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
@@ -70,6 +87,14 @@ static int fsl_dcu_load(struct drm_device *dev, unsigned long flags)
 		return ret;
 	}
 
+	if (of_device_is_compatible(fsl_dev->np, "fsl,ls1021a-dcu")) {
+		ret = fsl_dcu_scfg_config_ls1021a(fsl_dev->np);
+		if (ret < 0) {
+			dev_err(dev->dev, "failed to enable pixclk\n");
+			goto done;
+		}
+	}
+
 	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
 	if (ret < 0) {
 		dev_err(dev->dev, "failed to initialize vblank\n");
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
index e2049a0e8a92..566396013c04 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
@@ -160,6 +160,9 @@
 #define FSL_DCU_ARGB4444		12
 #define FSL_DCU_YUV422			14
 
+#define SCFG_PIXCLKCR			0x28
+#define SCFG_PIXCLKCR_PXCEN		BIT(31)
+
 #define VF610_LAYER_REG_NUM		9
 #define LS1021A_LAYER_REG_NUM		10
 
-- 
2.17.1

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Re: [PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[Stefan Agner]

Hi Matthias,

On 2020-08-20 12:58, Matthias Schiffer wrote:
> The PIXCLK needs to be enabled in SCFG before accessing the DCU on LS1021A,
> or the access will hang.

Hm, this seems a rather ad-hoc access to SCFG from the DCU. We do
support a pixel clock in the device tree bindings of fsl-dcu, so ideally
we should enable the pixel clock through the clock framework.

On the other hand, I guess that would mean adding a clock driver to flip
a single bit, which seems a bit excessive too.

I'd like a second opinion on that. Adding clk framework maintainers.

--
Stefan

> 
> Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> ---
>  drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
>  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 25 +++++++++++++++++++++++
>  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
>  3 files changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig b/drivers/gpu/drm/fsl-dcu/Kconfig
> index d7dd8ba90e3a..9e5a35e7c00c 100644
> --- a/drivers/gpu/drm/fsl-dcu/Kconfig
> +++ b/drivers/gpu/drm/fsl-dcu/Kconfig
> @@ -8,6 +8,7 @@ config DRM_FSL_DCU
>  	select DRM_PANEL
>  	select REGMAP_MMIO
>  	select VIDEOMODE_HELPERS
> +	select MFD_SYSCON if SOC_LS1021A
>  	help
>  	  Choose this option if you have an Freescale DCU chipset.
>  	  If M is selected the module will be called fsl-dcu-drm.
> diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> index abbc1ddbf27f..8a7556655581 100644
> --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> @@ -51,6 +51,23 @@ static const struct regmap_config fsl_dcu_regmap_config = {
>  	.volatile_reg = fsl_dcu_drm_is_volatile_reg,
>  };
>  
> +static int fsl_dcu_scfg_config_ls1021a(struct device_node *np)
> +{
> +	struct regmap *scfg;
> +
> +	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
> +	if (IS_ERR(scfg))
> +		return PTR_ERR(scfg);
> +
> +	/*
> +	 * For simplicity, enable the PIXCLK unconditionally. It might
> +	 * be possible to disable the clock in PM or on unload as a future
> +	 * improvement.
> +	 */
> +	return regmap_update_bits(scfg, SCFG_PIXCLKCR, SCFG_PIXCLKCR_PXCEN,
> +				  SCFG_PIXCLKCR_PXCEN);
> +}
> +
>  static void fsl_dcu_irq_uninstall(struct drm_device *dev)
>  {
>  	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
> @@ -70,6 +87,14 @@ static int fsl_dcu_load(struct drm_device *dev,
> unsigned long flags)
>  		return ret;
>  	}
>  
> +	if (of_device_is_compatible(fsl_dev->np, "fsl,ls1021a-dcu")) {
> +		ret = fsl_dcu_scfg_config_ls1021a(fsl_dev->np);
> +		if (ret < 0) {
> +			dev_err(dev->dev, "failed to enable pixclk\n");
> +			goto done;
> +		}
> +	}
> +
>  	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
>  	if (ret < 0) {
>  		dev_err(dev->dev, "failed to initialize vblank\n");
> diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> index e2049a0e8a92..566396013c04 100644
> --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> @@ -160,6 +160,9 @@
>  #define FSL_DCU_ARGB4444		12
>  #define FSL_DCU_YUV422			14
>  
> +#define SCFG_PIXCLKCR			0x28
> +#define SCFG_PIXCLKCR_PXCEN		BIT(31)
> +
>  #define VF610_LAYER_REG_NUM		9
>  #define LS1021A_LAYER_REG_NUM		10

Re: [PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[Stefan Agner]

Hi Matthias,

On 2020-08-20 12:58, Matthias Schiffer wrote:
> The PIXCLK needs to be enabled in SCFG before accessing the DCU on LS1021A,
> or the access will hang.

Hm, this seems a rather ad-hoc access to SCFG from the DCU. We do
support a pixel clock in the device tree bindings of fsl-dcu, so ideally
we should enable the pixel clock through the clock framework.

On the other hand, I guess that would mean adding a clock driver to flip
a single bit, which seems a bit excessive too.

I'd like a second opinion on that. Adding clk framework maintainers.

--
Stefan

> 
> Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> ---
>  drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
>  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 25 +++++++++++++++++++++++
>  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
>  3 files changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig b/drivers/gpu/drm/fsl-dcu/Kconfig
> index d7dd8ba90e3a..9e5a35e7c00c 100644
> --- a/drivers/gpu/drm/fsl-dcu/Kconfig
> +++ b/drivers/gpu/drm/fsl-dcu/Kconfig
> @@ -8,6 +8,7 @@ config DRM_FSL_DCU
>  	select DRM_PANEL
>  	select REGMAP_MMIO
>  	select VIDEOMODE_HELPERS
> +	select MFD_SYSCON if SOC_LS1021A
>  	help
>  	  Choose this option if you have an Freescale DCU chipset.
>  	  If M is selected the module will be called fsl-dcu-drm.
> diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> index abbc1ddbf27f..8a7556655581 100644
> --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> @@ -51,6 +51,23 @@ static const struct regmap_config fsl_dcu_regmap_config = {
>  	.volatile_reg = fsl_dcu_drm_is_volatile_reg,
>  };
>  
> +static int fsl_dcu_scfg_config_ls1021a(struct device_node *np)
> +{
> +	struct regmap *scfg;
> +
> +	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
> +	if (IS_ERR(scfg))
> +		return PTR_ERR(scfg);
> +
> +	/*
> +	 * For simplicity, enable the PIXCLK unconditionally. It might
> +	 * be possible to disable the clock in PM or on unload as a future
> +	 * improvement.
> +	 */
> +	return regmap_update_bits(scfg, SCFG_PIXCLKCR, SCFG_PIXCLKCR_PXCEN,
> +				  SCFG_PIXCLKCR_PXCEN);
> +}
> +
>  static void fsl_dcu_irq_uninstall(struct drm_device *dev)
>  {
>  	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
> @@ -70,6 +87,14 @@ static int fsl_dcu_load(struct drm_device *dev,
> unsigned long flags)
>  		return ret;
>  	}
>  
> +	if (of_device_is_compatible(fsl_dev->np, "fsl,ls1021a-dcu")) {
> +		ret = fsl_dcu_scfg_config_ls1021a(fsl_dev->np);
> +		if (ret < 0) {
> +			dev_err(dev->dev, "failed to enable pixclk\n");
> +			goto done;
> +		}
> +	}
> +
>  	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
>  	if (ret < 0) {
>  		dev_err(dev->dev, "failed to initialize vblank\n");
> diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> index e2049a0e8a92..566396013c04 100644
> --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> @@ -160,6 +160,9 @@
>  #define FSL_DCU_ARGB4444		12
>  #define FSL_DCU_YUV422			14
>  
> +#define SCFG_PIXCLKCR			0x28
> +#define SCFG_PIXCLKCR_PXCEN		BIT(31)
> +
>  #define VF610_LAYER_REG_NUM		9
>  #define LS1021A_LAYER_REG_NUM		10
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Re: [PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[Matthias Schiffer]

On Fri, 2020-08-21 at 15:41 +0200, Stefan Agner wrote:
> Hi Matthias,
> 
> On 2020-08-20 12:58, Matthias Schiffer wrote:
> > The PIXCLK needs to be enabled in SCFG before accessing the DCU on LS1021A,
> > or the access will hang.
> 
> Hm, this seems a rather ad-hoc access to SCFG from the DCU. We do
> support a pixel clock in the device tree bindings of fsl-dcu, so ideally
> we should enable the pixel clock through the clock framework.
> 
> On the other hand, I guess that would mean adding a clock driver to flip
> a single bit, which seems a bit excessive too.
> 
> I'd like a second opinion on that. Adding clk framework maintainers.
> 
> --
> Stefan

How do we proceed with this patch?

Kind regards,
Matthias



> 
> > 
> > Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> > ---
> >  drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
> >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 25 +++++++++++++++++++++++
> >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
> >  3 files changed, 29 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig b/drivers/gpu/drm/fsl-dcu/Kconfig
> > index d7dd8ba90e3a..9e5a35e7c00c 100644
> > --- a/drivers/gpu/drm/fsl-dcu/Kconfig
> > +++ b/drivers/gpu/drm/fsl-dcu/Kconfig
> > @@ -8,6 +8,7 @@ config DRM_FSL_DCU
> >  	select DRM_PANEL
> >  	select REGMAP_MMIO
> >  	select VIDEOMODE_HELPERS
> > +	select MFD_SYSCON if SOC_LS1021A
> >  	help
> >  	  Choose this option if you have an Freescale DCU chipset.
> >  	  If M is selected the module will be called fsl-dcu-drm.
> > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > index abbc1ddbf27f..8a7556655581 100644
> > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > @@ -51,6 +51,23 @@ static const struct regmap_config fsl_dcu_regmap_config = {
> >  	.volatile_reg = fsl_dcu_drm_is_volatile_reg,
> >  };
> >  
> > +static int fsl_dcu_scfg_config_ls1021a(struct device_node *np)
> > +{
> > +	struct regmap *scfg;
> > +
> > +	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
> > +	if (IS_ERR(scfg))
> > +		return PTR_ERR(scfg);
> > +
> > +	/*
> > +	 * For simplicity, enable the PIXCLK unconditionally. It might
> > +	 * be possible to disable the clock in PM or on unload as a future
> > +	 * improvement.
> > +	 */
> > +	return regmap_update_bits(scfg, SCFG_PIXCLKCR, SCFG_PIXCLKCR_PXCEN,
> > +				  SCFG_PIXCLKCR_PXCEN);
> > +}
> > +
> >  static void fsl_dcu_irq_uninstall(struct drm_device *dev)
> >  {
> >  	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
> > @@ -70,6 +87,14 @@ static int fsl_dcu_load(struct drm_device *dev,
> > unsigned long flags)
> >  		return ret;
> >  	}
> >  
> > +	if (of_device_is_compatible(fsl_dev->np, "fsl,ls1021a-dcu")) {
> > +		ret = fsl_dcu_scfg_config_ls1021a(fsl_dev->np);
> > +		if (ret < 0) {
> > +			dev_err(dev->dev, "failed to enable pixclk\n");
> > +			goto done;
> > +		}
> > +	}
> > +
> >  	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
> >  	if (ret < 0) {
> >  		dev_err(dev->dev, "failed to initialize vblank\n");
> > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > index e2049a0e8a92..566396013c04 100644
> > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > @@ -160,6 +160,9 @@
> >  #define FSL_DCU_ARGB4444		12
> >  #define FSL_DCU_YUV422			14
> >  
> > +#define SCFG_PIXCLKCR			0x28
> > +#define SCFG_PIXCLKCR_PXCEN		BIT(31)
> > +
> >  #define VF610_LAYER_REG_NUM		9
> >  #define LS1021A_LAYER_REG_NUM		10

Re: [PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[Matthias Schiffer]

On Fri, 2020-08-21 at 15:41 +0200, Stefan Agner wrote:
> Hi Matthias,
> 
> On 2020-08-20 12:58, Matthias Schiffer wrote:
> > The PIXCLK needs to be enabled in SCFG before accessing the DCU on LS1021A,
> > or the access will hang.
> 
> Hm, this seems a rather ad-hoc access to SCFG from the DCU. We do
> support a pixel clock in the device tree bindings of fsl-dcu, so ideally
> we should enable the pixel clock through the clock framework.
> 
> On the other hand, I guess that would mean adding a clock driver to flip
> a single bit, which seems a bit excessive too.
> 
> I'd like a second opinion on that. Adding clk framework maintainers.
> 
> --
> Stefan

How do we proceed with this patch?

Kind regards,
Matthias



> 
> > 
> > Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> > ---
> >  drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
> >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 25 +++++++++++++++++++++++
> >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
> >  3 files changed, 29 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig b/drivers/gpu/drm/fsl-dcu/Kconfig
> > index d7dd8ba90e3a..9e5a35e7c00c 100644
> > --- a/drivers/gpu/drm/fsl-dcu/Kconfig
> > +++ b/drivers/gpu/drm/fsl-dcu/Kconfig
> > @@ -8,6 +8,7 @@ config DRM_FSL_DCU
> >  	select DRM_PANEL
> >  	select REGMAP_MMIO
> >  	select VIDEOMODE_HELPERS
> > +	select MFD_SYSCON if SOC_LS1021A
> >  	help
> >  	  Choose this option if you have an Freescale DCU chipset.
> >  	  If M is selected the module will be called fsl-dcu-drm.
> > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > index abbc1ddbf27f..8a7556655581 100644
> > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > @@ -51,6 +51,23 @@ static const struct regmap_config fsl_dcu_regmap_config = {
> >  	.volatile_reg = fsl_dcu_drm_is_volatile_reg,
> >  };
> >  
> > +static int fsl_dcu_scfg_config_ls1021a(struct device_node *np)
> > +{
> > +	struct regmap *scfg;
> > +
> > +	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
> > +	if (IS_ERR(scfg))
> > +		return PTR_ERR(scfg);
> > +
> > +	/*
> > +	 * For simplicity, enable the PIXCLK unconditionally. It might
> > +	 * be possible to disable the clock in PM or on unload as a future
> > +	 * improvement.
> > +	 */
> > +	return regmap_update_bits(scfg, SCFG_PIXCLKCR, SCFG_PIXCLKCR_PXCEN,
> > +				  SCFG_PIXCLKCR_PXCEN);
> > +}
> > +
> >  static void fsl_dcu_irq_uninstall(struct drm_device *dev)
> >  {
> >  	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
> > @@ -70,6 +87,14 @@ static int fsl_dcu_load(struct drm_device *dev,
> > unsigned long flags)
> >  		return ret;
> >  	}
> >  
> > +	if (of_device_is_compatible(fsl_dev->np, "fsl,ls1021a-dcu")) {
> > +		ret = fsl_dcu_scfg_config_ls1021a(fsl_dev->np);
> > +		if (ret < 0) {
> > +			dev_err(dev->dev, "failed to enable pixclk\n");
> > +			goto done;
> > +		}
> > +	}
> > +
> >  	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
> >  	if (ret < 0) {
> >  		dev_err(dev->dev, "failed to initialize vblank\n");
> > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > index e2049a0e8a92..566396013c04 100644
> > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > @@ -160,6 +160,9 @@
> >  #define FSL_DCU_ARGB4444		12
> >  #define FSL_DCU_YUV422			14
> >  
> > +#define SCFG_PIXCLKCR			0x28
> > +#define SCFG_PIXCLKCR_PXCEN		BIT(31)
> > +
> >  #define VF610_LAYER_REG_NUM		9
> >  #define LS1021A_LAYER_REG_NUM		10

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Re: [PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[Matthias Schiffer]

On Fri, 2020-08-21 at 15:41 +0200, Stefan Agner wrote:
> Hi Matthias,
> 
> On 2020-08-20 12:58, Matthias Schiffer wrote:
> > The PIXCLK needs to be enabled in SCFG before accessing the DCU on LS1021A,
> > or the access will hang.
> 
> Hm, this seems a rather ad-hoc access to SCFG from the DCU. We do
> support a pixel clock in the device tree bindings of fsl-dcu, so ideally
> we should enable the pixel clock through the clock framework.
> 
> On the other hand, I guess that would mean adding a clock driver to flip
> a single bit, which seems a bit excessive too.
> 
> I'd like a second opinion on that. Adding clk framework maintainers.

It's been a while, and nobody else has given their opinion. How should
we proceed with this patch?

Matthias


> 
> --
> Stefan
> 
> > 
> > Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> > ---
> >  drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
> >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 25 +++++++++++++++++++++++
> >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
> >  3 files changed, 29 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig b/drivers/gpu/drm/fsl-dcu/Kconfig
> > index d7dd8ba90e3a..9e5a35e7c00c 100644
> > --- a/drivers/gpu/drm/fsl-dcu/Kconfig
> > +++ b/drivers/gpu/drm/fsl-dcu/Kconfig
> > @@ -8,6 +8,7 @@ config DRM_FSL_DCU
> >  	select DRM_PANEL
> >  	select REGMAP_MMIO
> >  	select VIDEOMODE_HELPERS
> > +	select MFD_SYSCON if SOC_LS1021A
> >  	help
> >  	  Choose this option if you have an Freescale DCU chipset.
> >  	  If M is selected the module will be called fsl-dcu-drm.
> > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > index abbc1ddbf27f..8a7556655581 100644
> > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > @@ -51,6 +51,23 @@ static const struct regmap_config fsl_dcu_regmap_config = {
> >  	.volatile_reg = fsl_dcu_drm_is_volatile_reg,
> >  };
> >  
> > +static int fsl_dcu_scfg_config_ls1021a(struct device_node *np)
> > +{
> > +	struct regmap *scfg;
> > +
> > +	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
> > +	if (IS_ERR(scfg))
> > +		return PTR_ERR(scfg);
> > +
> > +	/*
> > +	 * For simplicity, enable the PIXCLK unconditionally. It might
> > +	 * be possible to disable the clock in PM or on unload as a future
> > +	 * improvement.
> > +	 */
> > +	return regmap_update_bits(scfg, SCFG_PIXCLKCR, SCFG_PIXCLKCR_PXCEN,
> > +				  SCFG_PIXCLKCR_PXCEN);
> > +}
> > +
> >  static void fsl_dcu_irq_uninstall(struct drm_device *dev)
> >  {
> >  	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
> > @@ -70,6 +87,14 @@ static int fsl_dcu_load(struct drm_device *dev,
> > unsigned long flags)
> >  		return ret;
> >  	}
> >  
> > +	if (of_device_is_compatible(fsl_dev->np, "fsl,ls1021a-dcu")) {
> > +		ret = fsl_dcu_scfg_config_ls1021a(fsl_dev->np);
> > +		if (ret < 0) {
> > +			dev_err(dev->dev, "failed to enable pixclk\n");
> > +			goto done;
> > +		}
> > +	}
> > +
> >  	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
> >  	if (ret < 0) {
> >  		dev_err(dev->dev, "failed to initialize vblank\n");
> > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > index e2049a0e8a92..566396013c04 100644
> > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > @@ -160,6 +160,9 @@
> >  #define FSL_DCU_ARGB4444		12
> >  #define FSL_DCU_YUV422			14
> >  
> > +#define SCFG_PIXCLKCR			0x28
> > +#define SCFG_PIXCLKCR_PXCEN		BIT(31)
> > +
> >  #define VF610_LAYER_REG_NUM		9
> >  #define LS1021A_LAYER_REG_NUM		10

Re: [PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[Matthias Schiffer]

On Fri, 2020-08-21 at 15:41 +0200, Stefan Agner wrote:
> Hi Matthias,
> 
> On 2020-08-20 12:58, Matthias Schiffer wrote:
> > The PIXCLK needs to be enabled in SCFG before accessing the DCU on LS1021A,
> > or the access will hang.
> 
> Hm, this seems a rather ad-hoc access to SCFG from the DCU. We do
> support a pixel clock in the device tree bindings of fsl-dcu, so ideally
> we should enable the pixel clock through the clock framework.
> 
> On the other hand, I guess that would mean adding a clock driver to flip
> a single bit, which seems a bit excessive too.
> 
> I'd like a second opinion on that. Adding clk framework maintainers.

It's been a while, and nobody else has given their opinion. How should
we proceed with this patch?

Matthias


> 
> --
> Stefan
> 
> > 
> > Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> > ---
> >  drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
> >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 25 +++++++++++++++++++++++
> >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
> >  3 files changed, 29 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig b/drivers/gpu/drm/fsl-dcu/Kconfig
> > index d7dd8ba90e3a..9e5a35e7c00c 100644
> > --- a/drivers/gpu/drm/fsl-dcu/Kconfig
> > +++ b/drivers/gpu/drm/fsl-dcu/Kconfig
> > @@ -8,6 +8,7 @@ config DRM_FSL_DCU
> >  	select DRM_PANEL
> >  	select REGMAP_MMIO
> >  	select VIDEOMODE_HELPERS
> > +	select MFD_SYSCON if SOC_LS1021A
> >  	help
> >  	  Choose this option if you have an Freescale DCU chipset.
> >  	  If M is selected the module will be called fsl-dcu-drm.
> > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > index abbc1ddbf27f..8a7556655581 100644
> > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > @@ -51,6 +51,23 @@ static const struct regmap_config fsl_dcu_regmap_config = {
> >  	.volatile_reg = fsl_dcu_drm_is_volatile_reg,
> >  };
> >  
> > +static int fsl_dcu_scfg_config_ls1021a(struct device_node *np)
> > +{
> > +	struct regmap *scfg;
> > +
> > +	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
> > +	if (IS_ERR(scfg))
> > +		return PTR_ERR(scfg);
> > +
> > +	/*
> > +	 * For simplicity, enable the PIXCLK unconditionally. It might
> > +	 * be possible to disable the clock in PM or on unload as a future
> > +	 * improvement.
> > +	 */
> > +	return regmap_update_bits(scfg, SCFG_PIXCLKCR, SCFG_PIXCLKCR_PXCEN,
> > +				  SCFG_PIXCLKCR_PXCEN);
> > +}
> > +
> >  static void fsl_dcu_irq_uninstall(struct drm_device *dev)
> >  {
> >  	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
> > @@ -70,6 +87,14 @@ static int fsl_dcu_load(struct drm_device *dev,
> > unsigned long flags)
> >  		return ret;
> >  	}
> >  
> > +	if (of_device_is_compatible(fsl_dev->np, "fsl,ls1021a-dcu")) {
> > +		ret = fsl_dcu_scfg_config_ls1021a(fsl_dev->np);
> > +		if (ret < 0) {
> > +			dev_err(dev->dev, "failed to enable pixclk\n");
> > +			goto done;
> > +		}
> > +	}
> > +
> >  	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
> >  	if (ret < 0) {
> >  		dev_err(dev->dev, "failed to initialize vblank\n");
> > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > index e2049a0e8a92..566396013c04 100644
> > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > @@ -160,6 +160,9 @@
> >  #define FSL_DCU_ARGB4444		12
> >  #define FSL_DCU_YUV422			14
> >  
> > +#define SCFG_PIXCLKCR			0x28
> > +#define SCFG_PIXCLKCR_PXCEN		BIT(31)
> > +
> >  #define VF610_LAYER_REG_NUM		9
> >  #define LS1021A_LAYER_REG_NUM		10

Re: [PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[Matthias Schiffer]

On Thu, 2021-09-16 at 14:50 +0200, Matthias Schiffer wrote:
> On Fri, 2020-08-21 at 15:41 +0200, Stefan Agner wrote:
> > Hi Matthias,
> > 
> > On 2020-08-20 12:58, Matthias Schiffer wrote:
> > > The PIXCLK needs to be enabled in SCFG before accessing the DCU on LS1021A,
> > > or the access will hang.
> > 
> > Hm, this seems a rather ad-hoc access to SCFG from the DCU. We do
> > support a pixel clock in the device tree bindings of fsl-dcu, so ideally
> > we should enable the pixel clock through the clock framework.
> > 
> > On the other hand, I guess that would mean adding a clock driver to flip
> > a single bit, which seems a bit excessive too.
> > 
> > I'd like a second opinion on that. Adding clk framework maintainers.
> 
> It's been a while, and nobody else has given their opinion. How should
> we proceed with this patch?
> 
> Matthias

This patch is still blocked on a maintainer decision. Should I send a
rebased version of the current solution, or do we want to have a proper
clk driver to flip this bit?


> 
> 
> > 
> > --
> > Stefan
> > 
> > > 
> > > Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> > > ---
> > >  drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
> > >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 25 +++++++++++++++++++++++
> > >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
> > >  3 files changed, 29 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig b/drivers/gpu/drm/fsl-dcu/Kconfig
> > > index d7dd8ba90e3a..9e5a35e7c00c 100644
> > > --- a/drivers/gpu/drm/fsl-dcu/Kconfig
> > > +++ b/drivers/gpu/drm/fsl-dcu/Kconfig
> > > @@ -8,6 +8,7 @@ config DRM_FSL_DCU
> > >  	select DRM_PANEL
> > >  	select REGMAP_MMIO
> > >  	select VIDEOMODE_HELPERS
> > > +	select MFD_SYSCON if SOC_LS1021A
> > >  	help
> > >  	  Choose this option if you have an Freescale DCU chipset.
> > >  	  If M is selected the module will be called fsl-dcu-drm.
> > > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > > index abbc1ddbf27f..8a7556655581 100644
> > > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > > @@ -51,6 +51,23 @@ static const struct regmap_config fsl_dcu_regmap_config = {
> > >  	.volatile_reg = fsl_dcu_drm_is_volatile_reg,
> > >  };
> > >  
> > > +static int fsl_dcu_scfg_config_ls1021a(struct device_node *np)
> > > +{
> > > +	struct regmap *scfg;
> > > +
> > > +	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
> > > +	if (IS_ERR(scfg))
> > > +		return PTR_ERR(scfg);
> > > +
> > > +	/*
> > > +	 * For simplicity, enable the PIXCLK unconditionally. It might
> > > +	 * be possible to disable the clock in PM or on unload as a future
> > > +	 * improvement.
> > > +	 */
> > > +	return regmap_update_bits(scfg, SCFG_PIXCLKCR, SCFG_PIXCLKCR_PXCEN,
> > > +				  SCFG_PIXCLKCR_PXCEN);
> > > +}
> > > +
> > >  static void fsl_dcu_irq_uninstall(struct drm_device *dev)
> > >  {
> > >  	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
> > > @@ -70,6 +87,14 @@ static int fsl_dcu_load(struct drm_device *dev,
> > > unsigned long flags)
> > >  		return ret;
> > >  	}
> > >  
> > > +	if (of_device_is_compatible(fsl_dev->np, "fsl,ls1021a-dcu")) {
> > > +		ret = fsl_dcu_scfg_config_ls1021a(fsl_dev->np);
> > > +		if (ret < 0) {
> > > +			dev_err(dev->dev, "failed to enable pixclk\n");
> > > +			goto done;
> > > +		}
> > > +	}
> > > +
> > >  	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
> > >  	if (ret < 0) {
> > >  		dev_err(dev->dev, "failed to initialize vblank\n");
> > > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > > index e2049a0e8a92..566396013c04 100644
> > > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> > > @@ -160,6 +160,9 @@
> > >  #define FSL_DCU_ARGB4444		12
> > >  #define FSL_DCU_YUV422			14
> > >  
> > > +#define SCFG_PIXCLKCR			0x28
> > > +#define SCFG_PIXCLKCR_PXCEN		BIT(31)
> > > +
> > >  #define VF610_LAYER_REG_NUM		9
> > >  #define LS1021A_LAYER_REG_NUM		10

Re: [PATCH] drm: fsl-dcu: enable PIXCLK on LS1021A

[Stefan Agner]

On 2021-10-05 14:35, Matthias Schiffer wrote:
> On Thu, 2021-09-16 at 14:50 +0200, Matthias Schiffer wrote:
>> On Fri, 2020-08-21 at 15:41 +0200, Stefan Agner wrote:
>> > Hi Matthias,
>> >
>> > On 2020-08-20 12:58, Matthias Schiffer wrote:
>> > > The PIXCLK needs to be enabled in SCFG before accessing the DCU on LS1021A,
>> > > or the access will hang.
>> >
>> > Hm, this seems a rather ad-hoc access to SCFG from the DCU. We do
>> > support a pixel clock in the device tree bindings of fsl-dcu, so ideally
>> > we should enable the pixel clock through the clock framework.
>> >
>> > On the other hand, I guess that would mean adding a clock driver to flip
>> > a single bit, which seems a bit excessive too.
>> >
>> > I'd like a second opinion on that. Adding clk framework maintainers.
>>
>> It's been a while, and nobody else has given their opinion. How should
>> we proceed with this patch?
>>
>> Matthias
> 
> This patch is still blocked on a maintainer decision. Should I send a
> rebased version of the current solution, or do we want to have a proper
> clk driver to flip this bit?
> 

The clock maintainers haven't stated an opinion. I've seen similar hacks
for reset and other bits in other places, so I guess it's fine.

Can you also drop the np argument from fsl_dcu_scfg_config_ls1021a(), it
seems unnecessary.

--
Stefan

> 
>>
>>
>> >
>> > --
>> > Stefan
>> >
>> > >
>> > > Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
>> > > ---
>> > >  drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
>> > >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 25 +++++++++++++++++++++++
>> > >  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
>> > >  3 files changed, 29 insertions(+)
>> > >
>> > > diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig b/drivers/gpu/drm/fsl-dcu/Kconfig
>> > > index d7dd8ba90e3a..9e5a35e7c00c 100644
>> > > --- a/drivers/gpu/drm/fsl-dcu/Kconfig
>> > > +++ b/drivers/gpu/drm/fsl-dcu/Kconfig
>> > > @@ -8,6 +8,7 @@ config DRM_FSL_DCU
>> > >  	select DRM_PANEL
>> > >  	select REGMAP_MMIO
>> > >  	select VIDEOMODE_HELPERS
>> > > +	select MFD_SYSCON if SOC_LS1021A
>> > >  	help
>> > >  	  Choose this option if you have an Freescale DCU chipset.
>> > >  	  If M is selected the module will be called fsl-dcu-drm.
>> > > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
>> > > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
>> > > index abbc1ddbf27f..8a7556655581 100644
>> > > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
>> > > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
>> > > @@ -51,6 +51,23 @@ static const struct regmap_config fsl_dcu_regmap_config = {
>> > >  	.volatile_reg = fsl_dcu_drm_is_volatile_reg,
>> > >  };
>> > >
>> > > +static int fsl_dcu_scfg_config_ls1021a(struct device_node *np)
>> > > +{
>> > > +	struct regmap *scfg;
>> > > +
>> > > +	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
>> > > +	if (IS_ERR(scfg))
>> > > +		return PTR_ERR(scfg);
>> > > +
>> > > +	/*
>> > > +	 * For simplicity, enable the PIXCLK unconditionally. It might
>> > > +	 * be possible to disable the clock in PM or on unload as a future
>> > > +	 * improvement.
>> > > +	 */
>> > > +	return regmap_update_bits(scfg, SCFG_PIXCLKCR, SCFG_PIXCLKCR_PXCEN,
>> > > +				  SCFG_PIXCLKCR_PXCEN);
>> > > +}
>> > > +
>> > >  static void fsl_dcu_irq_uninstall(struct drm_device *dev)
>> > >  {
>> > >  	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
>> > > @@ -70,6 +87,14 @@ static int fsl_dcu_load(struct drm_device *dev,
>> > > unsigned long flags)
>> > >  		return ret;
>> > >  	}
>> > >
>> > > +	if (of_device_is_compatible(fsl_dev->np, "fsl,ls1021a-dcu")) {
>> > > +		ret = fsl_dcu_scfg_config_ls1021a(fsl_dev->np);
>> > > +		if (ret < 0) {
>> > > +			dev_err(dev->dev, "failed to enable pixclk\n");
>> > > +			goto done;
>> > > +		}
>> > > +	}
>> > > +
>> > >  	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
>> > >  	if (ret < 0) {
>> > >  		dev_err(dev->dev, "failed to initialize vblank\n");
>> > > diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
>> > > b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
>> > > index e2049a0e8a92..566396013c04 100644
>> > > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
>> > > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
>> > > @@ -160,6 +160,9 @@
>> > >  #define FSL_DCU_ARGB4444		12
>> > >  #define FSL_DCU_YUV422			14
>> > >
>> > > +#define SCFG_PIXCLKCR			0x28
>> > > +#define SCFG_PIXCLKCR_PXCEN		BIT(31)
>> > > +
>> > >  #define VF610_LAYER_REG_NUM		9
>> > >  #define LS1021A_LAYER_REG_NUM		10