[PATCH v2 4/5] drm/vc4: hdmi: Enable the scrambler
Dave Stevenson
dave.stevenson at raspberrypi.com
Thu Apr 1 11:30:45 UTC 2021
Hi Maxime
On Thu, 18 Mar 2021 at 09:29, Maxime Ripard <maxime at cerno.tech> wrote:
>
> The HDMI controller on the BCM2711 includes a scrambler in order to
> reach the modes that require it. Let's add the support for it.
Nit pick - it's as part of the HDMI2.0 spec.
> Signed-off-by: Maxime Ripard <maxime at cerno.tech>
> ---
> drivers/gpu/drm/vc4/vc4_hdmi.c | 56 +++++++++++++++++++++++++++++
> drivers/gpu/drm/vc4/vc4_hdmi_regs.h | 3 ++
> 2 files changed, 59 insertions(+)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 0924a1b9e186..530c83097b1a 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -35,6 +35,7 @@
> #include <drm/drm_edid.h>
> #include <drm/drm_probe_helper.h>
> #include <drm/drm_simple_kms_helper.h>
> +#include <drm/drm_scdc_helper.h>
> #include <linux/clk.h>
> #include <linux/component.h>
> #include <linux/i2c.h>
> @@ -76,6 +77,8 @@
> #define VC5_HDMI_VERTB_VSPO_SHIFT 16
> #define VC5_HDMI_VERTB_VSPO_MASK VC4_MASK(29, 16)
>
> +#define VC5_HDMI_SCRAMBLER_CTL_ENABLE BIT(0)
> +
> #define VC5_HDMI_DEEP_COLOR_CONFIG_1_INIT_PACK_PHASE_SHIFT 8
> #define VC5_HDMI_DEEP_COLOR_CONFIG_1_INIT_PACK_PHASE_MASK VC4_MASK(10, 8)
>
> @@ -457,6 +460,56 @@ static void vc4_hdmi_set_infoframes(struct drm_encoder *encoder)
> vc4_hdmi_set_audio_infoframe(encoder);
> }
>
> +static bool vc4_hdmi_supports_scrambling(struct drm_encoder *encoder,
> + struct drm_display_mode *mode)
> +{
> + struct vc4_hdmi_encoder *vc4_encoder = to_vc4_hdmi_encoder(encoder);
> + struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
> + struct drm_display_info *display = &vc4_hdmi->connector.display_info;
> +
> + if (!vc4_encoder->hdmi_monitor)
> + return false;
> +
> + if (!display->hdmi.scdc.supported ||
> + !display->hdmi.scdc.scrambling.supported)
> + return false;
> +
I think I made this comment last time, but possibly not very clearly.
Up to this point in the function is whether the display/hdmi interface
*supports* scrambling. The bit after is whether it is *required* to be
enabled by the mode.
At the moment, if the display/interface supports scrambling but the
mode doesn't need it, then the scrambling setup is never touched. That
makes a few assumptions about the default settings.
Boot with the firmware selecting 4k60 (ie scrambling on), but
video=HDMI-1:1920x1080 in the kernel command line and you'll have a
mess with scrambling enabled but not signalled.
I'd be happier if the display/interface says scrambling is supported
then we always call drm_scdc_set_high_tmds_clock_ratio,
drm_scdc_set_scrambling and set the VC5_HDMI_SCRAMBLER_CTL_ENABLE
register bit appropriately for the mode. Feel free to disagree with me
though.
Dave
> + if ((mode->clock * 1000) < HDMI_14_MAX_TMDS_CLK)
> + return false;
> +
> + return true;
> +}
> +
> +static void vc4_hdmi_enable_scrambling(struct drm_encoder *encoder)
> +{
> + struct drm_display_mode *mode = &encoder->crtc->state->adjusted_mode;
> + struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
> +
> + if (!vc4_hdmi_supports_scrambling(encoder, mode))
> + return;
> +
> + drm_scdc_set_high_tmds_clock_ratio(vc4_hdmi->ddc, true);
> + drm_scdc_set_scrambling(vc4_hdmi->ddc, true);
> +
> + HDMI_WRITE(HDMI_SCRAMBLER_CTL, HDMI_READ(HDMI_SCRAMBLER_CTL) |
> + VC5_HDMI_SCRAMBLER_CTL_ENABLE);
> +}
> +
> +static void vc4_hdmi_disable_scrambling(struct drm_encoder *encoder)
> +{
> + struct drm_display_mode *mode = &encoder->crtc->mode;
> + struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
> +
> + if (!vc4_hdmi_supports_scrambling(encoder, mode))
> + return;
> +
> + HDMI_WRITE(HDMI_SCRAMBLER_CTL, HDMI_READ(HDMI_SCRAMBLER_CTL) &
> + ~VC5_HDMI_SCRAMBLER_CTL_ENABLE);
> +
> + drm_scdc_set_scrambling(vc4_hdmi->ddc, false);
> + drm_scdc_set_high_tmds_clock_ratio(vc4_hdmi->ddc, false);
> +}
> +
> static void vc4_hdmi_encoder_post_crtc_disable(struct drm_encoder *encoder,
> struct drm_atomic_state *state)
> {
> @@ -469,6 +522,8 @@ static void vc4_hdmi_encoder_post_crtc_disable(struct drm_encoder *encoder,
>
> HDMI_WRITE(HDMI_VID_CTL,
> HDMI_READ(HDMI_VID_CTL) | VC4_HD_VID_CTL_BLANKPIX);
> +
> + vc4_hdmi_disable_scrambling(encoder);
> }
>
> static void vc4_hdmi_encoder_post_crtc_powerdown(struct drm_encoder *encoder,
> @@ -919,6 +974,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
> }
>
> vc4_hdmi_recenter_fifo(vc4_hdmi);
> + vc4_hdmi_enable_scrambling(encoder);
> }
>
> static void vc4_hdmi_encoder_enable(struct drm_encoder *encoder)
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi_regs.h b/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
> index e1b58eac766f..19d2fdc446bc 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
> @@ -100,6 +100,7 @@ enum vc4_hdmi_field {
> HDMI_RM_FORMAT,
> HDMI_RM_OFFSET,
> HDMI_SCHEDULER_CONTROL,
> + HDMI_SCRAMBLER_CTL,
> HDMI_SW_RESET_CONTROL,
> HDMI_TX_PHY_CHANNEL_SWAP,
> HDMI_TX_PHY_CLK_DIV,
> @@ -238,6 +239,7 @@ static const struct vc4_hdmi_register __maybe_unused vc5_hdmi_hdmi0_fields[] = {
> VC4_HDMI_REG(HDMI_GCP_CONFIG, 0x178),
> VC4_HDMI_REG(HDMI_GCP_WORD_1, 0x17c),
> VC4_HDMI_REG(HDMI_HOTPLUG, 0x1a8),
> + VC4_HDMI_REG(HDMI_SCRAMBLER_CTL, 0x1c4),
>
> VC5_DVP_REG(HDMI_CLOCK_STOP, 0x0bc),
> VC5_DVP_REG(HDMI_VEC_INTERFACE_XBAR, 0x0f0),
> @@ -317,6 +319,7 @@ static const struct vc4_hdmi_register __maybe_unused vc5_hdmi_hdmi1_fields[] = {
> VC4_HDMI_REG(HDMI_GCP_CONFIG, 0x178),
> VC4_HDMI_REG(HDMI_GCP_WORD_1, 0x17c),
> VC4_HDMI_REG(HDMI_HOTPLUG, 0x1a8),
> + VC4_HDMI_REG(HDMI_SCRAMBLER_CTL, 0x1c4),
>
> VC5_DVP_REG(HDMI_CLOCK_STOP, 0x0bc),
> VC5_DVP_REG(HDMI_VEC_INTERFACE_XBAR, 0x0f0),
> --
> 2.30.2
>
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