We are currently having FIFO underruns happening for kms_dsc test case,
problem is that, we check if curreny cdclk is >= pixel rate only if
there is a single VDSC engine enabled(i.e dsc_split=false) however if
we happen to have 2 VDSC engines enabled, we just kinda rely that this
would be automatically enough.
However pixel rate can be even >= than VDSC clock(cdclk) * 2, so in that
case even with 2 VDSC engines enabled, we still need to tweak it up.
So lets compare pixel rate with cdclk * slice count(VDSC engine count) and
check if it still requires bumping up.
Previously we had to bump up CDCLK many times for similar reasons.
v2: - Use new intel_dsc_get_num_vdsc_instances to determine number of VDSC
engines, instead of slice count(Ankit Nautiyal)
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_cdclk.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
index 4207863b7b2a..f04cebd01724 100644
--- a/drivers/gpu/drm/i915/display/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
@@ -37,6 +37,7 @@
#include "intel_pci_config.h"
#include "intel_pcode.h"
#include "intel_psr.h"
+#include "intel_vdsc.h"
#include "vlv_sideband.h"
/**
@@ -2607,9 +2608,17 @@ int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_state)
* When we decide to use only one VDSC engine, since
* each VDSC operates with 1 ppc throughput, pixel clock
* cannot be higher than the VDSC clock (cdclk)
+ * If there 2 VDSC engines, then pixel clock can't be higher than
+ * VDSC clock(cdclk) * 2. However even that can still be not enough.
+ * Slice count reflects amount of VDSC engines,
+ * so lets use that to determine, if need still need to tweak CDCLK higher.
*/
- if (crtc_state->dsc.compression_enable && !crtc_state->dsc.dsc_split)
- min_cdclk = max(min_cdclk, (int)crtc_state->pixel_rate);
+ if (crtc_state->dsc.compression_enable) {
+ u8 num_vdsc_instances = intel_dsc_get_num_vdsc_instances(crtc_state);
+
+ min_cdclk = max_t(int, min_cdclk,
+ crtc_state->pixel_rate / num_vdsc_instances);
+ }
/*
* HACK. Currently for TGL/DG2 platforms we calculate
--
2.37.3
