From nobody Thu Dec 18 21:11:51 2025 Received: from out-189.mta0.migadu.com (out-189.mta0.migadu.com [91.218.175.189]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 52AAC23353B for ; Tue, 14 Jan 2025 05:58:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.189 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736834294; cv=none; b=sTe9kLJzQW+RvpiLcPQPBLEhJV/4DqWNECVLxbVB8AaBaGqvsJTC0s//Pi0DZgYUBNdW55/FUDu6JIUPDKFPjq/CwKMGRnUK2fOWfkh3NdqehMfRfAjRugqtrjWqJneuVVeQJw6wPzwaK7AmCOXMinnE8D80a+x7nhQBFkVD92I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736834294; c=relaxed/simple; bh=RZCtCsZguzgNh0boj0GsEI1/CH+Ba/CQNMpWZzC0YeU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=POLeAe8dFBdQd+ddjM2cQaZaZS4e4btjNrehXIWZl07DFbuYE8AHKB86DjqgyeiujCM0yuX6fR+yZSb1PLRe/yy+SOjEb0s10DCNGF9OxB9zNZM06K94ufMvHa6LpvG77ohD0zCbNa7NBJUL0VR2NV5d7cmc7l37aQyZDT5EMH8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=lavWFqqb; arc=none smtp.client-ip=91.218.175.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="lavWFqqb" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1736834284; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iGc8nwl/8zBnibgfxQDUDI9Ul2vkfbVY2KHwHwuKwGU=; b=lavWFqqbtWNHEMXBDozx8yH8WlXuAPG5xSNknemWNdpWZ1PX+MaIcZ6YNIh+7shJRM/zsp 5HM5qU93YrO7cMIXWiFZdKvIiD/waV/OA8MXO2lVQ85uhn/+jx1gQ0dr+N7J1HcOR2ervv orzV/bS7hI/HXwsXxhZRzrAgf1qW1hE= From: Aradhya Bhatia To: Tomi Valkeinen , Dmitry Baryshkov , Laurent Pinchart , Andrzej Hajda , Neil Armstrong , Robert Foss , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter Cc: Nishanth Menon , Vignesh Raghavendra , Devarsh Thakkar , Praneeth Bajjuri , Udit Kumar , Jayesh Choudhary , DRI Development List , Linux Kernel List , Aradhya Bhatia Subject: [PATCH v7 12/12] drm/bridge: cdns-dsi: Use pre_enable/post_disable to enable/disable Date: Tue, 14 Jan 2025 11:26:26 +0530 Message-Id: <20250114055626.18816-13-aradhya.bhatia@linux.dev> In-Reply-To: <20250114055626.18816-1-aradhya.bhatia@linux.dev> References: <20250114055626.18816-1-aradhya.bhatia@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Aradhya Bhatia The cdns-dsi controller requires that it be turned on completely before the input DPI's source has begun streaming[0]. Not having that, allows for a small window before cdns-dsi enable and after cdns-dsi disable where the previous entity (in this case tidss's videoport) to continue streaming DPI video signals. This small window where cdns-dsi is disabled but is still receiving signals causes the input FIFO of cdns-dsi to get corrupted. This causes the colors to shift on the output display. The colors can either shift by one color component (R->G, G->B, B->R), or by two color components (R->B, G->R, B->G). Since tidss's videoport starts streaming via crtc enable hooks, we need cdns-dsi to be up and running before that. Now that the bridges are pre_enabled before crtc is enabled, and post_disabled after crtc is disabled, use the pre_enable and post_disable hooks to get cdns-dsi ready and running before the tidss videoport to get pass the color shift issues. [0]: See section 12.6.5.7.3 "Start-up Procedure" in J721E SoC TRM TRM Link: http://www.ti.com/lit/pdf/spruil1 Reviewed-by: Tomi Valkeinen Signed-off-by: Aradhya Bhatia Signed-off-by: Aradhya Bhatia --- .../gpu/drm/bridge/cadence/cdns-dsi-core.c | 62 ++++++++++--------- 1 file changed, 34 insertions(+), 28 deletions(-) diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c b/drivers/gpu/d= rm/bridge/cadence/cdns-dsi-core.c index d60254e1270c..cb79abd4c7e8 100644 --- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c +++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c @@ -669,13 +669,28 @@ cdns_dsi_bridge_mode_valid(struct drm_bridge *bridge, return MODE_OK; } =20 -static void cdns_dsi_bridge_atomic_disable(struct drm_bridge *bridge, - struct drm_bridge_state *old_bridge_state) +static void cdns_dsi_bridge_atomic_post_disable(struct drm_bridge *bridge, + struct drm_bridge_state *old_bridge_state) { struct cdns_dsi_input *input =3D bridge_to_cdns_dsi_input(bridge); struct cdns_dsi *dsi =3D input_to_dsi(input); u32 val; =20 + /* + * The cdns-dsi controller needs to be disabled after it's DPI source + * has stopped streaming. If this is not followed, there is a brief + * window before DPI source is disabled and after cdns-dsi controller + * has been disabled where the DPI stream is still on, but the cdns-dsi + * controller is not ready anymore to accept the incoming signals. This + * is one of the reasons why a shift in pixel colors is observed on + * displays that have cdns-dsi as one of the bridges. + * + * To mitigate this, disable this bridge from the bridge post_disable() + * hook, instead of the bridge _disable() hook. The bridge post_disable() + * hook gets called after the CRTC disable, where often many DPI sources + * disable their streams. + */ + val =3D readl(dsi->regs + MCTL_MAIN_DATA_CTL); val &=3D ~(IF_VID_SELECT_MASK | IF_VID_MODE | VID_EN | HOST_EOT_GEN | DISP_EOT_GEN); @@ -695,15 +710,6 @@ static void cdns_dsi_bridge_atomic_disable(struct drm_= bridge *bridge, pm_runtime_put(dsi->base.dev); } =20 -static void cdns_dsi_bridge_atomic_post_disable(struct drm_bridge *bridge, - struct drm_bridge_state *old_bridge_state) -{ - struct cdns_dsi_input *input =3D bridge_to_cdns_dsi_input(bridge); - struct cdns_dsi *dsi =3D input_to_dsi(input); - - pm_runtime_put(dsi->base.dev); -} - static void cdns_dsi_hs_init(struct cdns_dsi *dsi) { struct cdns_dsi_output *output =3D &dsi->output; @@ -773,8 +779,8 @@ static void cdns_dsi_init_link(struct cdns_dsi *dsi) dsi->link_initialized =3D true; } =20 -static void cdns_dsi_bridge_atomic_enable(struct drm_bridge *bridge, - struct drm_bridge_state *old_bridge_state) +static void cdns_dsi_bridge_atomic_pre_enable(struct drm_bridge *bridge, + struct drm_bridge_state *old_bridge_state) { struct cdns_dsi_input *input =3D bridge_to_cdns_dsi_input(bridge); struct cdns_dsi *dsi =3D input_to_dsi(input); @@ -789,6 +795,21 @@ static void cdns_dsi_bridge_atomic_enable(struct drm_b= ridge *bridge, u32 tmp, reg_wakeup, div, status; int nlanes; =20 + /* + * The cdns-dsi controller needs to be enabled before it's DPI source + * has begun streaming. If this is not followed, there is a brief window + * after DPI source enable and before cdns-dsi controller enable where + * the DPI stream is on, but the cdns-dsi controller is not ready to + * accept the incoming signals. This is one of the reasons why a shift + * in pixel colors is observed on displays that have cdns-dsi as one of + * the bridges. + * + * To mitigate this, enable this bridge from the bridge pre_enable() + * hook, instead of the bridge _enable() hook. The bridge pre_enable() + * hook gets called before the CRTC enable, where often many DPI sources + * enable their streams. + */ + if (WARN_ON(pm_runtime_get_sync(dsi->base.dev) < 0)) return; =20 @@ -935,19 +956,6 @@ static void cdns_dsi_bridge_atomic_enable(struct drm_b= ridge *bridge, writel(tmp, dsi->regs + MCTL_MAIN_EN); } =20 -static void cdns_dsi_bridge_atomic_pre_enable(struct drm_bridge *bridge, - struct drm_bridge_state *old_bridge_state) -{ - struct cdns_dsi_input *input =3D bridge_to_cdns_dsi_input(bridge); - struct cdns_dsi *dsi =3D input_to_dsi(input); - - if (WARN_ON(pm_runtime_get_sync(dsi->base.dev) < 0)) - return; - - cdns_dsi_init_link(dsi); - cdns_dsi_hs_init(dsi); -} - static u32 *cdns_dsi_bridge_get_input_bus_fmts(struct drm_bridge *bridge, struct drm_bridge_state *bridge_state, struct drm_crtc_state *crtc_state, @@ -1035,9 +1043,7 @@ cdns_dsi_bridge_atomic_reset(struct drm_bridge *bridg= e) static const struct drm_bridge_funcs cdns_dsi_bridge_funcs =3D { .attach =3D cdns_dsi_bridge_attach, .mode_valid =3D cdns_dsi_bridge_mode_valid, - .atomic_disable =3D cdns_dsi_bridge_atomic_disable, .atomic_pre_enable =3D cdns_dsi_bridge_atomic_pre_enable, - .atomic_enable =3D cdns_dsi_bridge_atomic_enable, .atomic_post_disable =3D cdns_dsi_bridge_atomic_post_disable, .atomic_check =3D cdns_dsi_bridge_atomic_check, .atomic_duplicate_state =3D cdns_dsi_bridge_atomic_duplicate_state, --=20 2.34.1