From nobody Sat Feb 7 16:00:13 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 5E9C7C00528 for ; Mon, 24 Jul 2023 15:16:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230253AbjGXPQx (ORCPT ); Mon, 24 Jul 2023 11:16:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229468AbjGXPQv (ORCPT ); Mon, 24 Jul 2023 11:16:51 -0400 X-Greylist: delayed 479 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Mon, 24 Jul 2023 08:16:50 PDT Received: from mail.fris.de (mail.fris.de [IPv6:2a01:4f8:c2c:390b::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 83B0512F for ; Mon, 24 Jul 2023 08:16:50 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id E13DEBFAE9; Mon, 24 Jul 2023 17:16:43 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fris.de; s=dkim; t=1690211807; h=from:subject:date:message-id:to:cc:mime-version: content-transfer-encoding; bh=IMigSv9byDtYWuiV7tdaUPxmriaCAFZ/avJIHWniWQU=; b=fsuxTw9q4KDwMJzKo+vcfreuXudubmmkbaOzhiDrk4yfV2KT94QvmVdxKC5sJRX35aoTy4 BrbWDXABdyFLv2yHAtTq3XBgMM+ji6QwNZpmsHkL35Q00GJp7DvZ+qOAnhm5pn0Ey5jbbU jiNrKUXu9RhzLNHcDoZwZSBrIA8H8gtWUDFWZ8gEapPf/FNhwKfkJvHjMEa8PNt1joAgqt f9vXRWHER5Xt1CI0txACLGVzdCPBJdnQjmprBvpW8EKXVwIHZwJzDO6EejLe7Rx2eUB//b 4wRXXnxW2oGanKws1MdhLekgG/2kTD48yU5A7Li6m9cyWPvwflZyxXARzt3Qow== From: Frieder Schrempf To: Andrzej Hajda , Daniel Vetter , David Airlie , dri-devel@lists.freedesktop.org, Frieder Schrempf , Inki Dae , Jagan Teki , linux-kernel@vger.kernel.org, Marek Szyprowski , Neil Armstrong , Robert Foss Cc: Tim Harvey , Adam Ford , Jernej Skrabec , Jonas Karlman , Laurent Pinchart , Marek Vasut Subject: [PATCH v2] drm: bridge: samsung-dsim: Fix init during host transfer Date: Mon, 24 Jul 2023 17:16:32 +0200 Message-ID: <20230724151640.555490-1-frieder@fris.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Last-TLS-Session-Version: TLSv1.3 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Frieder Schrempf In case the downstream bridge or panel uses DSI transfers before the DSI host was actually initialized through samsung_dsim_atomic_enable() which clears the stop state (LP11) mode, all transfers will fail. This happens with downstream bridges that are controlled by DSI commands such as the tc358762. As documented in [1] DSI hosts are expected to allow transfers outside the normal bridge enable/disable flow. To fix this make sure that stop state is cleared in samsung_dsim_host_transfer() which restores the previous behavior. We also factor out the common code to enable/disable stop state to samsung_dsim_set_stop_state(). [1] https://docs.kernel.org/gpu/drm-kms-helpers.html#mipi-dsi-bridge-operat= ion Fixes: 0c14d3130654 ("drm: bridge: samsung-dsim: Fix i.MX8M enable flow to = meet spec") Reported-by: Tim Harvey Signed-off-by: Frieder Schrempf Reviewed-by: Neil Armstrong Tested-by: Tim Harvey # --- Changes for v2: * Fix reversed stop state enable/disable in samsung_dsim_set_stop_state() Hi Tim, could you please give this patch a try and report back if it fixes your problem? Thanks! --- drivers/gpu/drm/bridge/samsung-dsim.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge= /samsung-dsim.c index 043b8109e64a..73ec60757dbc 100644 --- a/drivers/gpu/drm/bridge/samsung-dsim.c +++ b/drivers/gpu/drm/bridge/samsung-dsim.c @@ -1386,6 +1386,18 @@ static void samsung_dsim_disable_irq(struct samsung_= dsim *dsi) disable_irq(dsi->irq); } =20 +static void samsung_dsim_set_stop_state(struct samsung_dsim *dsi, bool ena= ble) +{ + u32 reg =3D samsung_dsim_read(dsi, DSIM_ESCMODE_REG); + + if (enable) + reg |=3D DSIM_FORCE_STOP_STATE; + else + reg &=3D ~DSIM_FORCE_STOP_STATE; + + samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg); +} + static int samsung_dsim_init(struct samsung_dsim *dsi) { const struct samsung_dsim_driver_data *driver_data =3D dsi->driver_data; @@ -1445,15 +1457,12 @@ static void samsung_dsim_atomic_enable(struct drm_b= ridge *bridge, struct drm_bridge_state *old_bridge_state) { struct samsung_dsim *dsi =3D bridge_to_dsi(bridge); - u32 reg; =20 if (samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) { samsung_dsim_set_display_mode(dsi); samsung_dsim_set_display_enable(dsi, true); } else { - reg =3D samsung_dsim_read(dsi, DSIM_ESCMODE_REG); - reg &=3D ~DSIM_FORCE_STOP_STATE; - samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg); + samsung_dsim_set_stop_state(dsi, false); } =20 dsi->state |=3D DSIM_STATE_VIDOUT_AVAILABLE; @@ -1463,16 +1472,12 @@ static void samsung_dsim_atomic_disable(struct drm_= bridge *bridge, struct drm_bridge_state *old_bridge_state) { struct samsung_dsim *dsi =3D bridge_to_dsi(bridge); - u32 reg; =20 if (!(dsi->state & DSIM_STATE_ENABLED)) return; =20 - if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) { - reg =3D samsung_dsim_read(dsi, DSIM_ESCMODE_REG); - reg |=3D DSIM_FORCE_STOP_STATE; - samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg); - } + if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) + samsung_dsim_set_stop_state(dsi, true); =20 dsi->state &=3D ~DSIM_STATE_VIDOUT_AVAILABLE; } @@ -1775,6 +1780,8 @@ static ssize_t samsung_dsim_host_transfer(struct mipi= _dsi_host *host, if (ret) return ret; =20 + samsung_dsim_set_stop_state(dsi, false); + ret =3D mipi_dsi_create_packet(&xfer.packet, msg); if (ret < 0) return ret; --=20 2.41.0