From nobody Thu Feb 12 06:17:39 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5948C77B73 for ; Thu, 27 Apr 2023 14:30:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244193AbjD0Oa4 (ORCPT ); Thu, 27 Apr 2023 10:30:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244110AbjD0OaZ (ORCPT ); Thu, 27 Apr 2023 10:30:25 -0400 Received: from mail11.truemail.it (mail11.truemail.it [217.194.8.81]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E933E4497 for ; Thu, 27 Apr 2023 07:30:19 -0700 (PDT) Received: from francesco-nb.pivistrello.it (93-49-2-63.ip317.fastwebnet.it [93.49.2.63]) by mail11.truemail.it (Postfix) with ESMTPA id C13F420B58; Thu, 27 Apr 2023 16:29:41 +0200 (CEST) From: Francesco Dolcini To: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , tomi.valkeinen@ideasonboard.com, dri-devel@lists.freedesktop.org Cc: Francesco Dolcini , David Airlie , Daniel Vetter , linux-kernel@vger.kernel.org Subject: [PATCH v1 5/9] drm/bridge: tc358768: fix TCLK_TRAILCNT computation Date: Thu, 27 Apr 2023 16:29:30 +0200 Message-Id: <20230427142934.55435-6-francesco@dolcini.it> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230427142934.55435-1-francesco@dolcini.it> References: <20230427142934.55435-1-francesco@dolcini.it> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Francesco Dolcini Correct computation of TCLK_TRAILCNT register. The driver does not implement non-continuous clock mode, so the actual value doesn't make a practical difference yet. However this change also ensures that the value does not write to reserved registers bits in case of under/overflow. This register must be set to a value that ensures that TCLK-TRAIL > 60ns and TEOT <=3D (105 ns + 12 x UI) with the actual value of TCLK-TRAIL being (TCLK_TRAILCNT + (1 to 2)) xHSByteClkCycle + (2 + (1 to 2)) * 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 --- drivers/gpu/drm/bridge/tc358768.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc3= 58768.c index aff400c36066..360c7c65f8c4 100644 --- a/drivers/gpu/drm/bridge/tc358768.c +++ b/drivers/gpu/drm/bridge/tc358768.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -638,6 +639,7 @@ static void tc358768_bridge_pre_enable(struct drm_bridg= e *bridge) struct mipi_dsi_device *dsi_dev =3D priv->output.dev; unsigned long mode_flags =3D dsi_dev->mode_flags; u32 val, val2, lptxcnt, hact, data_type; + s32 raw_val; const struct drm_display_mode *mode; u32 dsibclk_nsk, dsiclk_nsk, ui_nsk, phy_delay_nsk; u32 dsiclk, dsibclk, video_start; @@ -749,9 +751,9 @@ static void tc358768_bridge_pre_enable(struct drm_bridg= e *bridge) dev_dbg(priv->dev, "TCLK_HEADERCNT: 0x%x\n", val); tc358768_write(priv, TC358768_TCLK_HEADERCNT, val); =20 - /* TCLK_TRAIL > 60ns + 3*UI */ - val =3D 60 + tc358768_to_ns(3 * ui_nsk); - val =3D tc358768_ns_to_cnt(val, dsibclk_nsk) - 5; + /* TCLK_TRAIL > 60ns AND TEOT <=3D 105 ns + 12*UI */ + raw_val =3D tc358768_ns_to_cnt(60 + tc358768_to_ns(2 * ui_nsk), dsibclk_n= sk) - 5; + val =3D clamp(raw_val, 0, 127); dev_dbg(priv->dev, "TCLK_TRAILCNT: 0x%x\n", val); tc358768_write(priv, TC358768_TCLK_TRAILCNT, val); =20 --=20 2.25.1