drm/vc4: crtc: Increase setup cost in core clock calculation to handle extreme reduce...

commit 247a631f9c0ffb37ed0786a94cb4c5f2b6fc7ab1 upstream.

The formula that determines the core clock requirement based on pixel
clock and blanking has been determined experimentally to minimise the
clock while supporting all modes we've seen.

A new reduced blanking mode (4kp60 at 533MHz rather than the standard
594MHz) has been seen that doesn't produce a high enough clock and
results in "flip_done timed out" error.

Increase the setup cost in the formula to make this work. The result is
a reduced blanking mode increases by up to 7MHz while leaving the
standard timing
mode untouched

Link: https://github.com/raspberrypi/linux/issues/4446
Fixes: 16e101051f32 ("drm/vc4: Increase the core clock based on HVS load")
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20230127145558.446123-1-maxime@cerno.tech
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
index 0108613..7258975 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_crtc.c
+++ b/drivers/gpu/drm/vc4/vc4_crtc.c
@@ -711,7 +711,7 @@ static int vc4_crtc_atomic_check(struct drm_crtc *crtc,
                struct vc4_encoder *vc4_encoder = to_vc4_encoder(encoder);
 
                if (vc4_encoder->type == VC4_ENCODER_TYPE_HDMI0) {
-                       vc4_state->hvs_load = max(mode->clock * mode->hdisplay / mode->htotal + 1000,
+                       vc4_state->hvs_load = max(mode->clock * mode->hdisplay / mode->htotal + 8000,
                                                  mode->clock * 9 / 10) * 1000;
                } else {
                        vc4_state->hvs_load = mode->clock * 1000;