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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 AD516C433C1 for ; Tue, 23 Mar 2021 09:11:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6909D619BF for ; Tue, 23 Mar 2021 09:11:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229669AbhCWJLY (ORCPT ); Tue, 23 Mar 2021 05:11:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229836AbhCWJKz (ORCPT ); Tue, 23 Mar 2021 05:10:55 -0400 Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5519FC061756 for ; Tue, 23 Mar 2021 02:10:55 -0700 (PDT) Received: by mail-pf1-x434.google.com with SMTP id l3so13657354pfc.7 for ; Tue, 23 Mar 2021 02:10:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=WbW5E3Qe4WZYEnKi/sCmjQ1D+Tk7jZ1l2FTPgjhfZMQ=; b=yo8DL/aCSBDBcC0tqsQubEuqRWy6eLT5ir9zRrGsKjmyULNbNnccMqMnD7jmadxDw3 BGBok2NgqzzaR3uNkDmIajtKjfw1xjOqIJ/YLBW7GZNZbbv5CvEI9cgeue+5MtK4BpKN S1arzGTW1r4QJhbOQlc9o3b2oa2Lw+Ahw1ZqH5D2F0AMxncx0PgX2TScKhHBj8o47wKQ dADPkn6khGV+qRPCxXNv3qWXWtC0UTJPjxleX2xzunTLpcwnYPyR7WxEqEmzwO/kCH97 BvOa35YvQG7GVC9RhR+xBt2MsYZYMEWcBUIATnocN31bsvzJxFJWzKx+r42IA62GTkkc BzvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=WbW5E3Qe4WZYEnKi/sCmjQ1D+Tk7jZ1l2FTPgjhfZMQ=; b=Ojb1aXGhY+Oi0hEkI0oMQ17yzQv90wuhKA3TGOWHnqukIW8ABVUFu3ZsHmWW++ZuiI ArqcDk9DTgcWtZiun60V0YvTYUm4bUx7LD9opHOl2kT+JkdgsZUcVoIm5imMh0V6bwn8 XZBXlF6lU4vR/hRBdy2RL8iCRhRSLg6bibUp9D2eXpj52hGNqfhDj5ig8TV2iASsyfvX j013IFkzZB8hHiKTx//sFLXkwJbKyDt/G7AlMwi1zlm7e/wYAMYLAp4rVRjSamCvNimn GGuIze/L5PUCAk4QMRUYBxMVmshPOBc5QOZiOD1qX3uWCaC/aMzPX3NhCpjuHOlbRjXH /YiQ== X-Gm-Message-State: AOAM532fRz4gWAhsxfYcg4t+u5dlUo6hJGZTGJB7iyzgPwIypTp2KEmX jAmSIBZiWCTUUXMPINX68DVe4b18AKbh5tdctRVnLA== X-Google-Smtp-Source: ABdhPJxIS20E4tfWyNlD9+niQr2Ru+nuZgsxwL8HvALaLQyatNmIeXyoZrtnqaDhRUCxdvIm1IRm+HpRgaUET82BHa4= X-Received: by 2002:a63:ee4b:: with SMTP id n11mr3235216pgk.265.1616490654726; Tue, 23 Mar 2021 02:10:54 -0700 (PDT) MIME-Version: 1.0 References: <20210308120555.252524-1-adrien.grassein@gmail.com> <20210308120555.252524-3-adrien.grassein@gmail.com> In-Reply-To: <20210308120555.252524-3-adrien.grassein@gmail.com> From: Robert Foss Date: Tue, 23 Mar 2021 10:10:43 +0100 Message-ID: Subject: Re: [PATCH v7 2/2] drm/bridge: Introduce LT8912B DSI to HDMI bridge To: Adrien Grassein Cc: David Airlie , Daniel Vetter , Andrzej Hajda , Rob Herring , Neil Armstrong , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , dri-devel , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , linux-kernel , kernel test robot Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Hey Adrien, Sorry about the slow reply, but I just received the documentation from the vendor. So let's dig in to the HPD issue. > +static enum drm_connector_status lt8912_check_cable_status(struct lt8912 *lt) > +{ > + int ret; > + unsigned int reg_val; > + > + ret = regmap_read(lt->regmap[I2C_MAIN], 0xC1, ®_val); > + if (ret) > + return connector_status_unknown; > + > + if (reg_val & BIT(7)) > + return connector_status_connected; Register 0xc0 & BIT(7) - HPD signal after debounce Register 0xc0 & BIT(6) - HPD signal for TX HPD pad > + > +static int lt8912_probe(struct i2c_client *client, > + const struct i2c_device_id *id) > +{ > + static struct lt8912 *lt; > + int ret = 0; > + struct device *dev = &client->dev; > + > + lt = devm_kzalloc(dev, sizeof(struct lt8912), GFP_KERNEL); > + if (!lt) > + return -ENOMEM; > + > + lt->dev = dev; > + lt->i2c_client[0] = client; > + lt->cable_status = connector_status_unknown; > + lt->workq = create_workqueue("lt8912_workq"); Looking at [1] and maybe even better [2], I think this polling approach is the wrong way to go. And with access to documentation, I think we should be able to sort this out. Using the irq driver approach requires the interrupt pin to be configured. Pin 63 of the lt8912b is the IRQ output pin. In order to trigger interrupts based on it, the dt-binding would need to be updated[3][4] as well as whichever DTS you're using. [1] https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/bridge/analogix/anx7625.c#L1751 [2] https://github.com/torvalds/linux/blob/v5.11/drivers/gpu/drm/bridge/lontium-lt9611.c#L1160 [3] https://github.com/torvalds/linux/blob/v5.11/Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml#L27 [4] https://github.com/torvalds/linux/blob/v5.11/Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml#L144