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@xxxxxxxxxxxxxxx>
> > ---
> > 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
