From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 330F831F9B3 for ; Wed, 18 Mar 2026 17:40:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773855609; cv=none; b=GiRiePFfQBYFHpq08crEStbFgJVidEFEExOpPDXDA8zmP7Tk4naiCYqsEIhA+RzBoQqK8LsFm3NhGpHhGcc0rGH5oC/tbYbpMyJhcpfOLB0kQTmg0V2ra7IeBW0E1NPtsPetWej9L/n7u2usK3RM8w23E7pCUN3ymhCkOKvo++o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773855609; c=relaxed/simple; bh=AfoBKJ899kYDC02RCdrWGnp38KlkLKQkFxjJaZg3Z0M=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Z1wq6eLsleTR/yyAIrYaYG8rX8EETfEerHZGlQMfj6lmET/++Vgq0YkuIJh4wU2xIhml0R3Yaq8FObJJPspvlfKao4AMP55tANwNuoQxtFZ2tDvFgvcvoWikOhz68Cq+YR16OJp08LKeEpf4LRJYqYGlBCD5xRolzorCCTy0QY8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=jVX5SNkC; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="jVX5SNkC" Received: from killaraus.ideasonboard.com (2001-14ba-703d-e500--2a1.rev.dnainternet.fi [IPv6:2001:14ba:703d:e500::2a1]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 88D7B460; Wed, 18 Mar 2026 18:38:48 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1773855528; bh=AfoBKJ899kYDC02RCdrWGnp38KlkLKQkFxjJaZg3Z0M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jVX5SNkCqRiiVm1FzFn2Awdxhb9SvVwO1DTVKpsoLXblHvzYdeXoEKJ1WHXR69X6o +HX488OEcUAkSJZ8qCVsgs4W1kNBEZ5J/M+uRvdQlUU9g7E7fqAOh6dlFIJqMXmb/g 3YI85z0ZEsKFdRAp5wDNwNZ8uDCQiE35jUQbl8Po= Date: Wed, 18 Mar 2026 19:40:00 +0200 From: Laurent Pinchart To: Dmitry Baryshkov Cc: Andrzej Hajda , Neil Armstrong , Robert Foss , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Tomi Valkeinen , Boris Brezillon , Sam Ravnborg , Sebastian Reichel , Yongxing Mou , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] drm/bridge: display-connector: trigger initial HPD event for DP Message-ID: <20260318174000.GK633439@killaraus.ideasonboard.com> References: <20260314-dp-connector-hpd-v1-0-786044cedc17@oss.qualcomm.com> <20260314-dp-connector-hpd-v1-2-786044cedc17@oss.qualcomm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260314-dp-connector-hpd-v1-2-786044cedc17@oss.qualcomm.com> Hi Dmitry, Thank you for the patch. On Sat, Mar 14, 2026 at 02:43:12AM +0200, Dmitry Baryshkov wrote: > If the DisplayPort drivers use display-connector for the HPD detection, > the internal HPD state machine might be not active and thus the hardware > might be not able to handle cable detection correctly. Instead it will > depend on the externall HPD notifications to set the cable state, > bypassing the internal HPD state machine (for example this is the case > for the msm DP driver). > > However if the cable has been plugged before the HPD IRQ has been > enabled, there will be no HPD event coming. The drivers might fail > detection in such a case. Trigger the HPD notification after enabling > the HPD IRQ, propagating the cable insertion state. The explanation makes sense, but it sounds like to could apply the same way to HDMI. What am I missing ? Also, wouldn't it be better if the DRM core interrogated the state of the HPD signal when enabling HPD, instead of relying on all drivers to implement something similar as this patch ? > Fixes: 2e2bf3a5584d ("drm/bridge: display-connector: add DP support") > Reported-by: Yongxing Mou > Signed-off-by: Dmitry Baryshkov > --- > drivers/gpu/drm/bridge/display-connector.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/gpu/drm/bridge/display-connector.c b/drivers/gpu/drm/bridge/display-connector.c > index 6bb1134f75c3..f7a5bfd9c075 100644 > --- a/drivers/gpu/drm/bridge/display-connector.c > +++ b/drivers/gpu/drm/bridge/display-connector.c > @@ -12,6 +12,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -25,6 +26,8 @@ struct display_connector { > > struct regulator *supply; > struct gpio_desc *ddc_en; > + > + struct work_struct hpd_work; > }; > > static inline struct display_connector * > @@ -92,15 +95,29 @@ static void display_connector_hpd_enable(struct drm_bridge *bridge) > struct display_connector *conn = to_display_connector(bridge); > > enable_irq(conn->hpd_irq); > + > + if (conn->bridge.type == DRM_MODE_CONNECTOR_DisplayPort) > + schedule_work(&conn->hpd_work); > } > > static void display_connector_hpd_disable(struct drm_bridge *bridge) > { > struct display_connector *conn = to_display_connector(bridge); > > + if (conn->bridge.type == DRM_MODE_CONNECTOR_DisplayPort) > + cancel_work_sync(&conn->hpd_work); > + > disable_irq(conn->hpd_irq); > } > > +static void display_connector_hpd_work(struct work_struct *work) > +{ > + struct display_connector *conn = container_of(work, struct display_connector, hpd_work); > + struct drm_bridge *bridge = &conn->bridge; > + > + drm_bridge_hpd_notify(bridge, display_connector_detect(bridge)); > +} > + > static const struct drm_edid *display_connector_edid_read(struct drm_bridge *bridge, > struct drm_connector *connector) > { > @@ -395,6 +412,8 @@ static int display_connector_probe(struct platform_device *pdev) > conn->bridge.ops |= DRM_BRIDGE_OP_DETECT; > if (conn->hpd_irq >= 0) > conn->bridge.ops |= DRM_BRIDGE_OP_HPD; > + if (conn->hpd_irq >= 0 && type == DRM_MODE_CONNECTOR_DisplayPort) > + INIT_WORK(&conn->hpd_work, display_connector_hpd_work); > > dev_dbg(&pdev->dev, > "Found %s display connector '%s' %s DDC bus and %s HPD GPIO (ops 0x%x)\n", > -- Regards, Laurent Pinchart