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[v2,19/22] drm/tegra: dc: Tune up high priority request controls for Tegra20

Message ID 20200330010904.27643-20-digetx@gmail.com
State New
Headers show
Series Introduce memory interconnect for NVIDIA Tegra SoCs | expand

Commit Message

Dmitry Osipenko March 30, 2020, 1:09 a.m. UTC
Tegra20 has a high-priority-request control that allows to configure
when display's memory client should perform read requests with a higher
priority (Tegra30+ uses other means like Latency Allowance).

This patch changes the controls configuration in order to get a more
aggressive memory prefetching, which allows to reliably avoid FIFO
underflow when running on a lower memory frequency. This allow us
safely drop the memory bandwidth requirement by about two times in a
most popular use-cases (only one display active, video overlay inactive,
no scaling is done).

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/gpu/drm/tegra/dc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
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Patch

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index b540ac6ffdc4..564af302a965 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -1980,12 +1980,12 @@  static void tegra_crtc_atomic_enable(struct drm_crtc *crtc,
 		tegra_dc_writel(dc, value, DC_CMD_INT_POLARITY);
 
 		/* initialize timer */
-		value = CURSOR_THRESHOLD(0) | WINDOW_A_THRESHOLD(0x20) |
-			WINDOW_B_THRESHOLD(0x20) | WINDOW_C_THRESHOLD(0x20);
+		value = CURSOR_THRESHOLD(0) | WINDOW_A_THRESHOLD(0x70) |
+			WINDOW_B_THRESHOLD(0x30) | WINDOW_C_THRESHOLD(0x70);
 		tegra_dc_writel(dc, value, DC_DISP_DISP_MEM_HIGH_PRIORITY);
 
-		value = CURSOR_THRESHOLD(0) | WINDOW_A_THRESHOLD(1) |
-			WINDOW_B_THRESHOLD(1) | WINDOW_C_THRESHOLD(1);
+		value = CURSOR_THRESHOLD(0) | WINDOW_A_THRESHOLD(0) |
+			WINDOW_B_THRESHOLD(0) | WINDOW_C_THRESHOLD(0);
 		tegra_dc_writel(dc, value, DC_DISP_DISP_MEM_HIGH_PRIORITY_TIMER);
 
 		value = VBLANK_INT | WIN_A_UF_INT | WIN_B_UF_INT | WIN_C_UF_INT |