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SubjectRe: [PATCH v4 73/78] drm/vc4: hdmi: Switch to blank pixels when disabled
Hi Maxime

On Wed, 8 Jul 2020 at 18:44, Maxime Ripard <maxime@cerno.tech> wrote:
>
> In order to avoid pixels getting stuck in an unflushable FIFO, we need when
> we disable the HDMI controller to switch away from getting our pixels from
> the pixelvalve and instead use blank pixels, and switch back to the
> pixelvalve when we enable the HDMI controller.
>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

> ---
> drivers/gpu/drm/vc4/vc4_hdmi.c | 9 +++++++++
> drivers/gpu/drm/vc4/vc4_regs.h | 3 +++
> 2 files changed, 12 insertions(+)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index f56a718a3643..37463b016b47 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -325,6 +325,12 @@ static void vc4_hdmi_encoder_post_crtc_disable(struct drm_encoder *encoder)
> struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
>
> HDMI_WRITE(HDMI_RAM_PACKET_CONFIG, 0);
> +
> + HDMI_WRITE(HDMI_VID_CTL, HDMI_READ(HDMI_VID_CTL) |
> + VC4_HD_VID_CTL_CLRRGB | VC4_HD_VID_CTL_CLRSYNC);
> +
> + HDMI_WRITE(HDMI_VID_CTL,
> + HDMI_READ(HDMI_VID_CTL) | VC4_HD_VID_CTL_BLANKPIX);
> }
>
> static void vc4_hdmi_encoder_post_crtc_powerdown(struct drm_encoder *encoder)
> @@ -563,6 +569,9 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder)
> (vsync_pos ? 0 : VC4_HD_VID_CTL_VSYNC_LOW) |
> (hsync_pos ? 0 : VC4_HD_VID_CTL_HSYNC_LOW));
>
> + HDMI_WRITE(HDMI_VID_CTL,
> + HDMI_READ(HDMI_VID_CTL) & ~VC4_HD_VID_CTL_BLANKPIX);
> +
> if (vc4_encoder->hdmi_monitor) {
> HDMI_WRITE(HDMI_SCHEDULER_CONTROL,
> HDMI_READ(HDMI_SCHEDULER_CONTROL) |
> diff --git a/drivers/gpu/drm/vc4/vc4_regs.h b/drivers/gpu/drm/vc4/vc4_regs.h
> index d1e8961edaa0..30af52b406f1 100644
> --- a/drivers/gpu/drm/vc4/vc4_regs.h
> +++ b/drivers/gpu/drm/vc4/vc4_regs.h
> @@ -723,6 +723,9 @@
> # define VC4_HD_VID_CTL_FRAME_COUNTER_RESET BIT(29)
> # define VC4_HD_VID_CTL_VSYNC_LOW BIT(28)
> # define VC4_HD_VID_CTL_HSYNC_LOW BIT(27)
> +# define VC4_HD_VID_CTL_CLRSYNC BIT(24)
> +# define VC4_HD_VID_CTL_CLRRGB BIT(23)
> +# define VC4_HD_VID_CTL_BLANKPIX BIT(18)
>
> # define VC4_HD_CSC_CTL_ORDER_MASK VC4_MASK(7, 5)
> # define VC4_HD_CSC_CTL_ORDER_SHIFT 5
> --
> git-series 0.9.1

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