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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97007C433DF for ; Tue, 11 Aug 2020 02:43:24 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 6C1E62065D for ; Tue, 11 Aug 2020 02:43:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="AvcnLevq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6C1E62065D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D5E646E0CA; Tue, 11 Aug 2020 02:43:23 +0000 (UTC) Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by gabe.freedesktop.org (Postfix) with ESMTPS id D57616E0CA for ; Tue, 11 Aug 2020 02:43:22 +0000 (UTC) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 6460858; Tue, 11 Aug 2020 04:43:21 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1597113801; bh=WW5T77cfFpWObOoCK4Jd1gjvAgx5wXNgpO1aG1KQAGo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AvcnLevqsm+75glXW8u0IeEaT4/SPDcX+tRt01nszuRleIHWVqP/1zGNKhPdeBtwQ Rl4lNNNYSdi+4OxLFhJ3rzoHDVNBTshZjfwVsj+lNybDvr8CE2mUlW5SH1e3s9zW72 f/j9m4qvpu4MYOpl+jw/rDfGzRp/8Ev4jngdT+BE= Date: Tue, 11 Aug 2020 05:43:08 +0300 From: Laurent Pinchart To: Tomi Valkeinen , daniel@ffwll.ch Subject: Re: [PATCH v6 2/3] drm: bridge: Add support for Cadence MHDP DPI/DP bridge Message-ID: <20200811024308.GE13513@pendragon.ideasonboard.com> References: <1582712579-28504-1-git-send-email-yamonkar@cadence.com> <1582712579-28504-3-git-send-email-yamonkar@cadence.com> <20200311222053.GE4863@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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: , Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, jernej.skrabec@siol.net, Yuti Amonkar , narmstrong@baylibre.com, airlied@linux.ie, jonas@kwiboo.se, jsarha@ti.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, a.hajda@samsung.com, robh+dt@kernel.org, maxime@cerno.tech, praneeth@ti.com, sjakhade@cadence.com, mparab@cadence.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi Tomi, Daniel, On Thu, Mar 12, 2020 at 09:13:06AM +0200, Tomi Valkeinen wrote: > On 12/03/2020 00:20, Laurent Pinchart wrote: > >> + ret = load_firmware(mhdp); > >> + if (ret) > >> + goto phy_exit; > >> + > >> + drm_bridge_add(&mhdp->bridge); > > > What if someone starts using the bridge before the firmware is > > operational ? It seems that you should delay bridge registration until > > the firmware is loaded. It may make it possible to remove > > bridge_attached and solve the problem you mention in mhdp_fw_cb(). > > Handling the fw has been a bit of a pain... This is what we came up with to support all the > combinations (built-in/module, fw-userspace-helper/direct load, single-output/multiple-outputs). > > The idea is that when the driver is loaded and probed (with or without fw), the DP is "ready". If we > don't have fw yet, everything looks fine, but the connector stays in disconnected state. When we get > the fw, connector will get connected (only if there's a cable connected, of course). > > If we register the bridge only when we have fw, two things can happen: > > - If we get the fw only rather late (in case userspace fw helper), a userspace app (e.g. weston) > could already have been started, and failed due to there being no DRM card. > > - If we have two displays from the same display controller, say, DP and HDMI, the HDMI will only be > available when the DP is available. If the DP fw, for some reason, cannot be loaded, we never get HDMI. These seem to me to be deficiencies in the graphics stack. We don't have to solve them now, but I'm curious to know if anyone would have ideas on how this should ideally be addressed. Daniel, what do you think ? -- Regards, Laurent Pinchart _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel