diff options
Diffstat (limited to 'drivers/gpu/drm')
| -rw-r--r-- | drivers/gpu/drm/tegra/dc.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c index dbb2d00268b2..a56fccc428d5 100644 --- a/drivers/gpu/drm/tegra/dc.c +++ b/drivers/gpu/drm/tegra/dc.c @@ -53,6 +53,18 @@ static void tegra_dc_cursor_commit(struct tegra_dc *dc) tegra_dc_writel(dc, CURSOR_ACT_REQ, DC_CMD_STATE_CONTROL); } +/* + * Double-buffered registers have two copies: ASSEMBLY and ACTIVE. When the + * *_ACT_REQ bits are set the ASSEMBLY copy is latched into the ACTIVE copy. + * Latching happens mmediately if the display controller is in STOP mode or + * on the next frame boundary otherwise. + * + * Triple-buffered registers have three copies: ASSEMBLY, ARM and ACTIVE. The + * ASSEMBLY copy is latched into the ARM copy immediately after *_UPDATE bits + * are written. When the *_ACT_REQ bits are written, the ARM copy is latched + * into the ACTIVE copy, either immediately if the display controller is in + * STOP mode, or at the next frame boundary otherwise. + */ static void tegra_dc_commit(struct tegra_dc *dc) { tegra_dc_writel(dc, GENERAL_ACT_REQ << 8, DC_CMD_STATE_CONTROL); |