diff mbox series

[RFC,v2,5/6] drm/i915/scaler: Check if vblank is sufficient for scaler

Message ID 20241217180710.1048355-6-mitulkumar.ajitkumar.golani@intel.com (mailing list archive)
State New, archived
Headers show
Series Check if is vblank too short | expand

Commit Message

Golani, Mitulkumar Ajitkumar Dec. 17, 2024, 6:07 p.m. UTC
Check if vblank is too short for scaler prefill latency.

Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
---
 drivers/gpu/drm/i915/display/skl_watermark.c | 22 ++++++++++++++++++++
 1 file changed, 22 insertions(+)

Comments

Nautiyal, Ankit K Dec. 23, 2024, 9:59 a.m. UTC | #1
On 12/17/2024 11:37 PM, Mitul Golani wrote:
> Check if vblank is too short for scaler prefill latency.
>
> Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
> ---
>   drivers/gpu/drm/i915/display/skl_watermark.c | 22 ++++++++++++++++++++
>   1 file changed, 22 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
> index d3506e8ccd9b..a538e2b82c12 100644
> --- a/drivers/gpu/drm/i915/display/skl_watermark.c
> +++ b/drivers/gpu/drm/i915/display/skl_watermark.c
> @@ -2292,6 +2292,27 @@ static int icl_build_plane_wm(struct intel_crtc_state *crtc_state,
>   	return 0;
>   }
>   
> +static int
> +scaler_prefill_time(const struct intel_crtc_state *crtc_state)
> +{
> +	const struct intel_crtc_scaler_state *scaler_state =
> +					&crtc_state->scaler_state;
> +	int scaler_users = scaler_state->scaler_users;
> +	int count = 0;
> +	int hscale = scaler_state->scalers[0].hscale;
> +	int vscale = scaler_state->scalers[0].vscale;
> +
> +	while (scaler_users) {
> +		count += scaler_users & 1;
> +		scaler_users >>= 1;
> +	}
> +
> +	if (count > 1)
> +		return (4 * crtc_state->linetime * hscale * vscale);

This will not work. We need to take proper precision into account to do 
this calculation.

currently hscale,vscale are left shifted by 16.

Regards,

Ankit

> +	else
> +		return (4 * crtc_state->linetime);
> +}
> +
>   static bool
>   skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
>   			int wm0_lines, int latency)
> @@ -2302,6 +2323,7 @@ skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
>   	/* FIXME missing scaler and DSC pre-fill time */
>   	return crtc_state->framestart_delay +
>   		intel_usecs_to_scanlines(adjusted_mode, latency) +
> +		scaler_prefill_time(crtc_state) +
>   		wm0_lines >
>   		adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vblank_start;
>   }
Jani Nikula Dec. 30, 2024, 2:17 p.m. UTC | #2
On Tue, 17 Dec 2024, Mitul Golani <mitulkumar.ajitkumar.golani@intel.com> wrote:
> Check if vblank is too short for scaler prefill latency.
>
> Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
> ---
>  drivers/gpu/drm/i915/display/skl_watermark.c | 22 ++++++++++++++++++++
>  1 file changed, 22 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
> index d3506e8ccd9b..a538e2b82c12 100644
> --- a/drivers/gpu/drm/i915/display/skl_watermark.c
> +++ b/drivers/gpu/drm/i915/display/skl_watermark.c
> @@ -2292,6 +2292,27 @@ static int icl_build_plane_wm(struct intel_crtc_state *crtc_state,
>  	return 0;
>  }
>  
> +static int
> +scaler_prefill_time(const struct intel_crtc_state *crtc_state)
> +{
> +	const struct intel_crtc_scaler_state *scaler_state =
> +					&crtc_state->scaler_state;
> +	int scaler_users = scaler_state->scaler_users;
> +	int count = 0;
> +	int hscale = scaler_state->scalers[0].hscale;
> +	int vscale = scaler_state->scalers[0].vscale;
> +
> +	while (scaler_users) {
> +		count += scaler_users & 1;
> +		scaler_users >>= 1;
> +	}

See the hweight* family of functions for counting bits.

BR,
Jani.

> +
> +	if (count > 1)
> +		return (4 * crtc_state->linetime * hscale * vscale);
> +	else
> +		return (4 * crtc_state->linetime);
> +}
> +
>  static bool
>  skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
>  			int wm0_lines, int latency)
> @@ -2302,6 +2323,7 @@ skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
>  	/* FIXME missing scaler and DSC pre-fill time */
>  	return crtc_state->framestart_delay +
>  		intel_usecs_to_scanlines(adjusted_mode, latency) +
> +		scaler_prefill_time(crtc_state) +
>  		wm0_lines >
>  		adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vblank_start;
>  }
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index d3506e8ccd9b..a538e2b82c12 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -2292,6 +2292,27 @@  static int icl_build_plane_wm(struct intel_crtc_state *crtc_state,
 	return 0;
 }
 
+static int
+scaler_prefill_time(const struct intel_crtc_state *crtc_state)
+{
+	const struct intel_crtc_scaler_state *scaler_state =
+					&crtc_state->scaler_state;
+	int scaler_users = scaler_state->scaler_users;
+	int count = 0;
+	int hscale = scaler_state->scalers[0].hscale;
+	int vscale = scaler_state->scalers[0].vscale;
+
+	while (scaler_users) {
+		count += scaler_users & 1;
+		scaler_users >>= 1;
+	}
+
+	if (count > 1)
+		return (4 * crtc_state->linetime * hscale * vscale);
+	else
+		return (4 * crtc_state->linetime);
+}
+
 static bool
 skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
 			int wm0_lines, int latency)
@@ -2302,6 +2323,7 @@  skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
 	/* FIXME missing scaler and DSC pre-fill time */
 	return crtc_state->framestart_delay +
 		intel_usecs_to_scanlines(adjusted_mode, latency) +
+		scaler_prefill_time(crtc_state) +
 		wm0_lines >
 		adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vblank_start;
 }