From 7292d99b6de959212e12aefd36a4382f7dfc8684 Mon Sep 17 00:00:00 2001 From: Francesco Dolcini Date: Mon, 17 Apr 2023 13:03:09 +0200 Subject: drm/bridge: tc358768: fix THS_ZEROCNT computation Correct computation of THS_ZEROCNT register. This register must be set to a value that ensure that THS_PREPARE + THS_ZERO > 145ns + 10*UI with the actual value of (THS_PREPARE + THS_ZERO) being ((1 to 2) + 1 + (TCLK_ZEROCNT + 1) + (3 to 4)) x ByteClk cycle + + HSByteClk x (2 + (1 to 2)) + (PHY delay) with PHY delay being about (8 + (5 to 6)) x MIPIBitClk cycle in the BitClk conversion. Upstream-Status: Submitted [https://lore.kernel.org/all/20230427142934.55435-1-francesco@dolcini.it/] Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver") Signed-off-by: Francesco Dolcini --- drivers/gpu/drm/bridge/tc358768.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c index 259fa3fb5cd1..550f1567c1f8 100644 --- a/drivers/gpu/drm/bridge/tc358768.c +++ b/drivers/gpu/drm/bridge/tc358768.c @@ -761,9 +761,10 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge) /* 40ns + 4*UI < THS_PREPARE < 85ns + 6*UI */ val = 50 + tc358768_to_ns(4 * ui_nsk); val = tc358768_ns_to_cnt(val, dsibclk_nsk) - 1; - /* THS_ZERO > 145ns + 10*UI */ - val2 = tc358768_ns_to_cnt(145 - tc358768_to_ns(ui_nsk), dsibclk_nsk); - val |= (val2 - tc358768_to_ns(phy_delay_nsk)) << 8; + /* THS_PREPARE + THS_ZERO > 145ns + 10*UI */ + raw_val = tc358768_ns_to_cnt(145 - tc358768_to_ns(3 * ui_nsk), dsibclk_nsk) - 10; + val2 = clamp(raw_val, 0, 127); + val |= val2 << 8; dev_dbg(priv->dev, "THS_HEADERCNT: 0x%x\n", val); tc358768_write(priv, TC358768_THS_HEADERCNT, val); -- cgit v1.2.3