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Message-ID: <CAPY8ntAwCamnfFDZssuRRJ45Xe8shK+YxiO=Lcr-w34c4L-_2A@mail.gmail.com>
Date: Tue, 2 Nov 2021 17:12:29 +0000
From: Dave Stevenson <dave.stevenson@...pberrypi.com>
To: Maxime Ripard <maxime@...no.tech>
Cc: DRI Development <dri-devel@...ts.freedesktop.org>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Thomas Zimmermann <tzimmermann@...e.de>,
Daniel Vetter <daniel.vetter@...el.com>,
David Airlie <airlied@...ux.ie>,
linux-rpi-kernel@...ts.infradead.org,
LKML <linux-kernel@...r.kernel.org>,
Maxime Ripard <mripard@...nel.org>,
Nicolas Saenz Julienne <nsaenz@...nel.org>,
bcm-kernel-feedback-list@...adcom.com,
Emma Anholt <emma@...olt.net>,
Phil Elwell <phil@...pberrypi.com>,
Tim Gover <tim.gover@...pberrypi.com>,
Dom Cobley <dom@...pberrypi.com>
Subject: Re: [PATCH v8 10/10] drm/vc4: Increase the core clock based on HVS load
On Mon, 25 Oct 2021 at 16:29, Maxime Ripard <maxime@...no.tech> wrote:
>
> Depending on a given HVS output (HVS to PixelValves) and input (planes
> attached to a channel) load, the HVS needs for the core clock to be
> raised above its boot time default.
>
> Failing to do so will result in a vblank timeout and a stalled display
> pipeline.
>
> Signed-off-by: Maxime Ripard <maxime@...no.tech>
I will make the comment that this does a load of computation of hvs
load when running on hvs4 (BCM2835/6/7), even though it's redundant on
those chips.
The overhead is relatively minimal, but could be bypassed if viewed necessary.
Otherwise
Reviewed-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
> ---
> drivers/gpu/drm/vc4/vc4_crtc.c | 15 +++++
> drivers/gpu/drm/vc4/vc4_drv.h | 2 +
> drivers/gpu/drm/vc4/vc4_kms.c | 110 ++++++++++++++++++++++++++++++---
> 3 files changed, 118 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
> index 6decaa12a078..287dbc89ad64 100644
> --- a/drivers/gpu/drm/vc4/vc4_crtc.c
> +++ b/drivers/gpu/drm/vc4/vc4_crtc.c
> @@ -659,12 +659,27 @@ static int vc4_crtc_atomic_check(struct drm_crtc *crtc,
> struct vc4_crtc_state *vc4_state = to_vc4_crtc_state(crtc_state);
> struct drm_connector *conn;
> struct drm_connector_state *conn_state;
> + struct drm_encoder *encoder;
> int ret, i;
>
> ret = vc4_hvs_atomic_check(crtc, state);
> if (ret)
> return ret;
>
> + encoder = vc4_get_crtc_encoder(crtc, crtc_state);
> + if (encoder) {
> + const struct drm_display_mode *mode = &crtc_state->adjusted_mode;
> + struct vc4_encoder *vc4_encoder = to_vc4_encoder(encoder);
> +
> + mode = &crtc_state->adjusted_mode;
> + if (vc4_encoder->type == VC4_ENCODER_TYPE_HDMI0) {
> + vc4_state->hvs_load = max(mode->clock * mode->hdisplay / mode->htotal + 1000,
> + mode->clock * 9 / 10) * 1000;
> + } else {
> + vc4_state->hvs_load = mode->clock * 1000;
> + }
> + }
> +
> for_each_new_connector_in_state(state, conn, conn_state,
> i) {
> if (conn_state->crtc != crtc)
> diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> index 813c5d0ea98e..4329e09d357c 100644
> --- a/drivers/gpu/drm/vc4/vc4_drv.h
> +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> @@ -558,6 +558,8 @@ struct vc4_crtc_state {
> unsigned int bottom;
> } margins;
>
> + unsigned long hvs_load;
> +
> /* Transitional state below, only valid during atomic commits */
> bool update_muxing;
> };
> diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
> index 41cb4869da50..79d4d9dd1394 100644
> --- a/drivers/gpu/drm/vc4/vc4_kms.c
> +++ b/drivers/gpu/drm/vc4/vc4_kms.c
> @@ -39,9 +39,11 @@ static struct vc4_ctm_state *to_vc4_ctm_state(struct drm_private_state *priv)
>
> struct vc4_hvs_state {
> struct drm_private_state base;
> + unsigned long core_clock_rate;
>
> struct {
> unsigned in_use: 1;
> + unsigned long fifo_load;
> struct drm_crtc_commit *pending_commit;
> } fifo_state[HVS_NUM_CHANNELS];
> };
> @@ -340,10 +342,19 @@ static void vc4_atomic_commit_tail(struct drm_atomic_state *state)
> struct vc4_hvs *hvs = vc4->hvs;
> struct drm_crtc_state *old_crtc_state;
> struct drm_crtc_state *new_crtc_state;
> + struct vc4_hvs_state *new_hvs_state;
> struct drm_crtc *crtc;
> struct vc4_hvs_state *old_hvs_state;
> int i;
>
> + old_hvs_state = vc4_hvs_get_old_global_state(state);
> + if (WARN_ON(!old_hvs_state))
> + return;
> +
> + new_hvs_state = vc4_hvs_get_new_global_state(state);
> + if (WARN_ON(!new_hvs_state))
> + return;
> +
> for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
> struct vc4_crtc_state *vc4_crtc_state;
>
> @@ -354,12 +365,13 @@ static void vc4_atomic_commit_tail(struct drm_atomic_state *state)
> vc4_hvs_mask_underrun(dev, vc4_crtc_state->assigned_channel);
> }
>
> - if (vc4->hvs->hvs5)
> - clk_set_min_rate(hvs->core_clk, 500000000);
> + if (vc4->hvs->hvs5) {
> + unsigned long core_rate = max_t(unsigned long,
> + 500000000,
> + new_hvs_state->core_clock_rate);
>
> - old_hvs_state = vc4_hvs_get_old_global_state(state);
> - if (!old_hvs_state)
> - return;
> + clk_set_min_rate(hvs->core_clk, core_rate);
> + }
>
> for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) {
> struct vc4_crtc_state *vc4_crtc_state =
> @@ -399,8 +411,12 @@ static void vc4_atomic_commit_tail(struct drm_atomic_state *state)
>
> drm_atomic_helper_cleanup_planes(dev, state);
>
> - if (vc4->hvs->hvs5)
> - clk_set_min_rate(hvs->core_clk, 0);
> + if (vc4->hvs->hvs5) {
> + drm_dbg(dev, "Running the core clock at %lu Hz\n",
> + new_hvs_state->core_clock_rate);
> +
> + clk_set_min_rate(hvs->core_clk, new_hvs_state->core_clock_rate);
> + }
> }
>
> static int vc4_atomic_commit_setup(struct drm_atomic_state *state)
> @@ -657,9 +673,9 @@ vc4_hvs_channels_duplicate_state(struct drm_private_obj *obj)
>
> __drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);
>
> -
> for (i = 0; i < HVS_NUM_CHANNELS; i++) {
> state->fifo_state[i].in_use = old_state->fifo_state[i].in_use;
> + state->fifo_state[i].fifo_load = old_state->fifo_state[i].fifo_load;
>
> if (!old_state->fifo_state[i].pending_commit)
> continue;
> @@ -668,6 +684,8 @@ vc4_hvs_channels_duplicate_state(struct drm_private_obj *obj)
> drm_crtc_commit_get(old_state->fifo_state[i].pending_commit);
> }
>
> + state->core_clock_rate = old_state->core_clock_rate;
> +
> return &state->base;
> }
>
> @@ -822,6 +840,76 @@ static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
> return 0;
> }
>
> +static int
> +vc4_core_clock_atomic_check(struct drm_atomic_state *state)
> +{
> + struct vc4_dev *vc4 = to_vc4_dev(state->dev);
> + struct drm_private_state *priv_state;
> + struct vc4_hvs_state *hvs_new_state;
> + struct vc4_load_tracker_state *load_state;
> + struct drm_crtc_state *old_crtc_state, *new_crtc_state;
> + struct drm_crtc *crtc;
> + unsigned int num_outputs;
> + unsigned long pixel_rate;
> + unsigned long cob_rate;
> + unsigned int i;
> +
> + priv_state = drm_atomic_get_private_obj_state(state,
> + &vc4->load_tracker);
> + if (IS_ERR(priv_state))
> + return PTR_ERR(priv_state);
> +
> + load_state = to_vc4_load_tracker_state(priv_state);
> +
> + hvs_new_state = vc4_hvs_get_global_state(state);
> + if (!hvs_new_state)
> + return -EINVAL;
> +
> + for_each_oldnew_crtc_in_state(state, crtc,
> + old_crtc_state,
> + new_crtc_state,
> + i) {
> + if (old_crtc_state->active) {
> + struct vc4_crtc_state *old_vc4_state =
> + to_vc4_crtc_state(old_crtc_state);
> + unsigned int channel = old_vc4_state->assigned_channel;
> +
> + hvs_new_state->fifo_state[channel].fifo_load = 0;
> + }
> +
> + if (new_crtc_state->active) {
> + struct vc4_crtc_state *new_vc4_state =
> + to_vc4_crtc_state(new_crtc_state);
> + unsigned int channel = new_vc4_state->assigned_channel;
> +
> + hvs_new_state->fifo_state[channel].fifo_load =
> + new_vc4_state->hvs_load;
> + }
> + }
> +
> + cob_rate = 0;
> + num_outputs = 0;
> + for (i = 0; i < HVS_NUM_CHANNELS; i++) {
> + if (!hvs_new_state->fifo_state[i].in_use)
> + continue;
> +
> + num_outputs++;
> + cob_rate += hvs_new_state->fifo_state[i].fifo_load;
> + }
> +
> + pixel_rate = load_state->hvs_load;
> + if (num_outputs > 1) {
> + pixel_rate = (pixel_rate * 40) / 100;
> + } else {
> + pixel_rate = (pixel_rate * 60) / 100;
> + }
> +
> + hvs_new_state->core_clock_rate = max(cob_rate, pixel_rate);
> +
> + return 0;
> +}
> +
> +
> static int
> vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
> {
> @@ -839,7 +927,11 @@ vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
> if (ret)
> return ret;
>
> - return vc4_load_tracker_atomic_check(state);
> + ret = vc4_load_tracker_atomic_check(state);
> + if (ret)
> + return ret;
> +
> + return vc4_core_clock_atomic_check(state);
> }
>
> static struct drm_mode_config_helper_funcs vc4_mode_config_helpers = {
> --
> 2.31.1
>
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