From: Francesco Dolcini Date: Thu, 27 Apr 2023 14:29:29 +0000 (+0200) Subject: drm/bridge: tc358768: fix TCLK_ZEROCNT computation X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=f9cf811374f42fca31ac34aaf59ee2ae72b89879;p=linux.git drm/bridge: tc358768: fix TCLK_ZEROCNT computation Correct computation of TCLK_ZEROCNT register. This register must be set to a value that ensure that (TCLK-PREPARECNT + TCLK-ZERO) > 300ns with the actual value of (TCLK-PREPARECNT + TCLK-ZERO) being (1 to 2) + (TCLK_ZEROCNT + 1)) x HSByteClkCycle + (PHY output delay) with PHY output delay being about (2 to 3) x MIPIBitClk cycle in the BitClk conversion. Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver") Signed-off-by: Francesco Dolcini Reviewed-by: Robert Foss Signed-off-by: Robert Foss Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-5-francesco@dolcini.it --- diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c index 429bd49c53c4e..487bfe33edc88 100644 --- a/drivers/gpu/drm/bridge/tc358768.c +++ b/drivers/gpu/drm/bridge/tc358768.c @@ -743,10 +743,10 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge) /* 38ns < TCLK_PREPARE < 95ns */ val = tc358768_ns_to_cnt(65, dsibclk_nsk) - 1; - /* TCLK_PREPARE > 300ns */ - val2 = tc358768_ns_to_cnt(300 + tc358768_to_ns(3 * ui_nsk), - dsibclk_nsk); - val |= (val2 - tc358768_to_ns(phy_delay_nsk - dsibclk_nsk)) << 8; + /* TCLK_PREPARE + TCLK_ZERO > 300ns */ + val2 = tc358768_ns_to_cnt(300 - tc358768_to_ns(2 * ui_nsk), + dsibclk_nsk) - 2; + val |= val2 << 8; dev_dbg(priv->dev, "TCLK_HEADERCNT: 0x%x\n", val); tc358768_write(priv, TC358768_TCLK_HEADERCNT, val);