Re: [PATCH 2/2] drm: fsl-dcu: enable PIXCLK on LS1021A

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Hi,

any feedback on this?

Best regards
Alexander

Am Dienstag, 17. Januar 2023, 12:08:01 CET schrieb Alexander Stein:
> From: Matthias Schiffer <matthias.schiffer@tq-group.com>
> 
> The PIXCLK needs to be enabled in SCFG before accessing certain DCU
> registers, or the access will hang.
> 
> Signed-off-by: Matthias Schiffer <matthias.schiffer@tq-group.com>
> Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> ---
>  drivers/gpu/drm/fsl-dcu/Kconfig           |  1 +
>  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 14 ++++++++++++++
>  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h |  3 +++
>  3 files changed, 18 insertions(+)
> 
> diff --git a/drivers/gpu/drm/fsl-dcu/Kconfig
> b/drivers/gpu/drm/fsl-dcu/Kconfig index 5ca71ef87325..c9ee98693b48 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
> 418887654bac..314cb8af89ee 100644
> --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> @@ -100,12 +100,26 @@ static void fsl_dcu_irq_uninstall(struct drm_device
> *dev) static int fsl_dcu_load(struct drm_device *dev, unsigned long flags)
> {
>  	struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;
> +	struct regmap *scfg;
>  	int ret;
> 
>  	ret = fsl_dcu_drm_modeset_init(fsl_dev);
>  	if (ret < 0)
>  		return dev_err_probe(dev->dev, ret, "failed to initialize 
mode
> setting\n");
> 
> +	scfg = syscon_regmap_lookup_by_compatible("fsl,ls1021a-scfg");
> +	if (PTR_ERR(scfg) != -ENODEV) {
> +		/*
> +		 * For simplicity, enable the PIXCLK unconditionally. 
Disabling
> +		 * the clock in PM or on unload could be implemented as a 
future
> +		 * improvement.
> +		 */
> +		ret = regmap_update_bits(scfg, SCFG_PIXCLKCR, 
SCFG_PIXCLKCR_PXCEN,
> +					SCFG_PIXCLKCR_PXCEN);
> +		if (ret < 0)
> +			return dev_err_probe(dev->dev, ret, "failed to 
enable pixclk\n");
> +	}
> +
>  	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