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(-)
diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c index 12b318bb8475..48dad375b470 100644 --- a/drivers/gpu/drm/tegra/dc.c +++ b/drivers/gpu/drm/tegra/dc.c @@ -1971,12 +1971,12 @@ 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 |