From mboxrd@z Thu Jan 1 00:00:00 1970 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B07D3F588C2 for ; Mon, 20 Apr 2026 12:55:01 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 91C2F10E5B3; Mon, 20 Apr 2026 12:54:59 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="m0GMfT/J"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by gabe.freedesktop.org (Postfix) with ESMTPS id CD77710E5A1 for ; Mon, 20 Apr 2026 12:54:47 +0000 (UTC) Received: from [127.0.1.1] (91-158-153-178.elisa-laajakaista.fi [91.158.153.178]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 01B4E2704; Mon, 20 Apr 2026 14:53:08 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1776689589; bh=IvwEX2fU924HEbulijRI36HD4eNyDkBbd7Rixi29VYk=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=m0GMfT/J84VzHJ7wqmKBi3OQZtVF+pLpoVGkXAVwpvrWoKBhQ5QM+HaHIleAgBLl1 YR8bYQa64SjUuFDtsrFYXRJqc8W8UabqrqZ1PU2ODStn0fsgxG8NlVymMktihhVRqV 8LaL6tF0V82Nof3kH2a3UERNrssIH7QQu5gWewbo= From: Tomi Valkeinen Date: Mon, 20 Apr 2026 15:54:18 +0300 Subject: [PATCH 11/15] drm/tidss: oldi: Fix OLDI signal polarities MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260420-beagley-ai-display-v1-11-f628543dfd14@ideasonboard.com> References: <20260420-beagley-ai-display-v1-0-f628543dfd14@ideasonboard.com> In-Reply-To: <20260420-beagley-ai-display-v1-0-f628543dfd14@ideasonboard.com> To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Lee Jones , Aradhya Bhatia , Nishanth Menon , Vignesh Raghavendra , Swamil Jain , Devarsh Thakkar , Louis Chauvet Cc: devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Tomi Valkeinen X-Mailer: b4 0.15-dev-c25d1 X-Developer-Signature: v=1; a=openpgp-sha256; l=4956; i=tomi.valkeinen@ideasonboard.com; h=from:subject:message-id; bh=IvwEX2fU924HEbulijRI36HD4eNyDkBbd7Rixi29VYk=; b=owEBbQKS/ZANAwAIAfo9qoy8lh71AcsmYgBp5iIGnSXSgBcG5idVSXF0ab4UKMWuDuhuI5yb4 /wb6GB0fm2JAjMEAAEIAB0WIQTEOAw+ll79gQef86f6PaqMvJYe9QUCaeYiBgAKCRD6PaqMvJYe 9WYwD/wPS+6ZXwbt7vmlISMMAdElDEPq3phVVnt1LixXC8vIF2gvtU92QmDe+SBHEv+q6Btrt2M pfpTa+s4lFwt4DXmGVsF71b151HTmwAMj7r4GR1m0N72Ry6eO7dPfZMLnRQO14ifE2ssUGimvb4 JOVcipMbfOpjd0tnImdeULl2FVdI73Sxz4DuaWyFOLvNZcgdzJ/cdrRjnp5ykS7cR7yntKjUAnX oAwpy6QXCkCSMoU7PLxRqVktXEpejRKhomrWQ1+S3v1/FYNMGAYUehUkhf6DKfOke9EaTXw8kwP A7clvVOiA92GRctkvBrjkmr77u+3Qn21dPSV9YSSPE1B4I4lqTTsSUeoi4UBYWkmdCY01nBO1ID j4GIFq3WbAt96eqp2o8MiBm8NeI774wyVe27HEalg6cw7TMk5bAnQ88Vfqe1dELncN0+/KglROX qTmHyS64+JU6rU3V5rGaldNwQ2rRAPeDnNdnpyrsnwD89GCSCIHMcKK3wO3XHSf4eOnqrZmymeA CTNw9pVa3k0ouhSoAjgCbIOAs/vmXI0+WFZAAQBvYGNOg5sLCljDHmt4h9xm7Xw6LSaRm296blk CesD6QlPPbbstp7Hpsq3t53BtFBzdHFDdXop1z5CmronHBTOwr2J9V38MeBuUJjWag4dVOpQiLe 5MGacCI8helYFSQ== X-Developer-Key: i=tomi.valkeinen@ideasonboard.com; a=openpgp; fpr=C4380C3E965EFD81079FF3A7FA3DAA8CBC961EF5 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" OLDI has a few issues with how it handles the signal polarities: - It always sets OLDI_DEPOL, which means DE active low - It sets DRM_BUS_FLAG_DE_HIGH in struct drm_bridge_timings, i.e. reverse to the OLDI_DEPOL - It sets DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE in struct drm_bridge_timings, but the TRM says "The DSS interface is clocked on the rising edge of OLDI_FWD_P_CLK pixel clock", which I read as "OLDI samples on rising edge". - But the defined drm_bridge_timings is not actually used anywhere, even if it is set to bridge->timings, so the bus flags are just ignored. However, based on my testing, OLDI_DEPOL bit or the edge on which data and syncs are driven doesn't seem to affect the OLDI output. Possibly it's not as robust, but I did not see any effect with an oscilloscope. However, the code is still quite broken, so let's fix it: - Remove drm_bridge_timings - Set the correct input_bus_cfg.flags in tidss_oldi_atomic_check() - Set OLDI_DEPOL based on the DE bus flag Signed-off-by: Tomi Valkeinen --- drivers/gpu/drm/tidss/tidss_oldi.c | 38 ++++++++++++++++++++++++++++---------- 1 file changed, 28 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/tidss/tidss_oldi.c b/drivers/gpu/drm/tidss/tidss_oldi.c index 17c535bfa057..e925ddaa4fd6 100644 --- a/drivers/gpu/drm/tidss/tidss_oldi.c +++ b/drivers/gpu/drm/tidss/tidss_oldi.c @@ -164,7 +164,8 @@ static void tidss_oldi_tx_power(struct tidss_oldi *oldi, bool enable) regmap_update_bits(oldi->io_ctrl, OLDI_PD_CTRL, mask, enable ? 0 : mask); } -static int tidss_oldi_config(struct tidss_oldi *oldi) +static int tidss_oldi_config(struct tidss_oldi *oldi, + struct drm_bridge_state *bridge_state) { const struct oldi_bus_format *bus_fmt = NULL; u32 oldi_cfg = 0; @@ -183,7 +184,8 @@ static int tidss_oldi_config(struct tidss_oldi *oldi) "OLDI%u: DSS port width %d not supported\n", oldi->oldi_instance, bus_fmt->data_width); - oldi_cfg |= OLDI_DEPOL; + if (bridge_state->input_bus_cfg.flags & DRM_BUS_FLAG_DE_LOW) + oldi_cfg |= OLDI_DEPOL; /* 1 = active low */ oldi_cfg = (oldi_cfg & (~OLDI_MAP)) | (bus_fmt->oldi_mode_reg_val << 1); @@ -220,6 +222,22 @@ static int tidss_oldi_config(struct tidss_oldi *oldi) return ret; } +static int tidss_oldi_atomic_check(struct drm_bridge *bridge, + struct drm_bridge_state *bridge_state, + struct drm_crtc_state *crtc_state, + struct drm_connector_state *conn_state) +{ + bridge_state->input_bus_cfg.flags &= + ~(DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE | + DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE); + + bridge_state->input_bus_cfg.flags |= + DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE | + DRM_BUS_FLAG_SYNC_SAMPLE_POSEDGE; + + return 0; +} + static void tidss_oldi_atomic_pre_enable(struct drm_bridge *bridge, struct drm_atomic_state *state) { @@ -228,6 +246,7 @@ static void tidss_oldi_atomic_pre_enable(struct drm_bridge *bridge, struct drm_connector_state *conn_state; struct drm_crtc_state *crtc_state; struct drm_display_mode *mode; + struct drm_bridge_state *bridge_state; if (oldi->link_type == OLDI_MODE_SECONDARY_CLONE_SINGLE_LINK) return; @@ -245,10 +264,14 @@ static void tidss_oldi_atomic_pre_enable(struct drm_bridge *bridge, if (WARN_ON(!crtc_state)) return; + bridge_state = drm_atomic_get_new_bridge_state(state, bridge); + if (WARN_ON(!bridge_state)) + return; + mode = &crtc_state->adjusted_mode; /* Configure the OLDI params*/ - tidss_oldi_config(oldi); + tidss_oldi_config(oldi, bridge_state); /* Set the OLDI serial clock (7 times the pixel clock) */ tidss_oldi_set_serial_clk(oldi, mode->clock * 7 * 1000); @@ -329,7 +352,8 @@ tidss_oldi_mode_valid(struct drm_bridge *bridge, } static const struct drm_bridge_funcs tidss_oldi_bridge_funcs = { - .attach = tidss_oldi_bridge_attach, + .attach = tidss_oldi_bridge_attach, + .atomic_check = tidss_oldi_atomic_check, .atomic_pre_enable = tidss_oldi_atomic_pre_enable, .atomic_post_disable = tidss_oldi_atomic_post_disable, .atomic_get_input_bus_fmts = tidss_oldi_atomic_get_input_bus_fmts, @@ -440,11 +464,6 @@ static int get_parent_dss_vp(struct device_node *oldi_tx, u32 *parent_vp) return -ENODEV; } -static const struct drm_bridge_timings default_tidss_oldi_timings = { - .input_bus_flags = DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE - | DRM_BUS_FLAG_DE_HIGH, -}; - void tidss_oldi_deinit(struct tidss_device *tidss) { for (int i = 0; i < tidss->num_oldis; i++) { @@ -598,7 +617,6 @@ int tidss_oldi_init(struct tidss_device *tidss) /* Register the bridge. */ oldi->bridge.of_node = child; oldi->bridge.driver_private = oldi; - oldi->bridge.timings = &default_tidss_oldi_timings; tidss->oldis[tidss->num_oldis++] = oldi; tidss->is_ext_vp_clk[oldi->parent_vp] = true; -- 2.43.0