From patchwork Thu May 7 21:34:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 11534941 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D3C5581 for ; Thu, 7 May 2020 21:35:43 +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 B252F21473 for ; Thu, 7 May 2020 21:35:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="ENdo3wyF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B252F21473 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org 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 8757C6EA70; Thu, 7 May 2020 21:35:36 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mail-pj1-x1041.google.com (mail-pj1-x1041.google.com [IPv6:2607:f8b0:4864:20::1041]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4317C6EA70 for ; Thu, 7 May 2020 21:35:34 +0000 (UTC) Received: by mail-pj1-x1041.google.com with SMTP id 7so4291864pjo.0 for ; Thu, 07 May 2020 14:35:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=fbjU22n436fNS4tm9Z/DQEhrNON6zU3/PI+8bjMf9/o=; b=ENdo3wyFIDnDOOps1rk+zv5ProXXQ+9MQz5G/1HA4jSM5UDNXkl9+hmeBnvG9M3leO NSh4AFWRaMg3Lf/9zJc93B0KoxcSPKM5Ml1/hYEPKQFxomyzrN2OmnKaWC1HQe39/uQm EOhKMqjbzPhv07nF6b2So6ZrxNKoRCqeCCMpU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=fbjU22n436fNS4tm9Z/DQEhrNON6zU3/PI+8bjMf9/o=; b=NYY1lbZ7tLgXiD41E+Vo7UFg0ekYoOIJzzyRMFa5pF8EOiZQuecGq9+zc/SI2NFRwz KiVAuc8Yk/ExvjiraldqfZWEY12Fi03qVLNhYaA/Y8a/6XdMvQPqtcLQFeiItuo2Fvrp H7YcbHO0vG9DaZoT78fAffyUnUKaRMYpp6wZlKPNChGz0M7Bx70QaebaeQ3bjE4h1Rlo MlLcCCJbhPAtVFmCxAs0ZBelkEETy8X3IU4tx/S4k2CMo6V+v9BEQy5pffXTFjk3QmeA sw/o7TrOK0y8u/EGdckQBFWsS2dd30zCrCJEos2u89HfFiD0hKNeodN8dvW5GUD8C6Ba oupQ== X-Gm-Message-State: AGi0PublHUgVakxCAQZJf3CMQRdnkIZbiu8gKnMFddv86RoSJaM5ljsy 0KfgqEOLSungcFkNT7wP0ZAUNQ== X-Google-Smtp-Source: APiQypJBBpiB37bVUcSXNEkVSPOGBlPdXdGwMwr4Q977C7AhF9IZS/u97Q/SlXzZLRIaBaM4TgLqgA== X-Received: by 2002:a17:90a:2ac2:: with SMTP id i2mr2277713pjg.91.1588887333807; Thu, 07 May 2020 14:35:33 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:1:24fa:e766:52c9:e3b2]) by smtp.gmail.com with ESMTPSA id i10sm5884860pfa.166.2020.05.07.14.35.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 May 2020 14:35:33 -0700 (PDT) From: Douglas Anderson To: linus.walleij@linaro.org, bgolaszewski@baylibre.com, airlied@linux.ie, daniel@ffwll.ch, robh+dt@kernel.org, narmstrong@baylibre.com, a.hajda@samsung.com, Laurent.pinchart@ideasonboard.com, spanda@codeaurora.org Subject: [PATCH v5 5/6] dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd Date: Thu, 7 May 2020 14:34:59 -0700 Message-Id: <20200507143354.v5.5.I72892d485088e57378a4748c86bc0f6c2494d807@changeid> X-Mailer: git-send-email 2.26.2.645.ge9eca65c58-goog In-Reply-To: <20200507213500.241695-1-dianders@chromium.org> References: <20200507213500.241695-1-dianders@chromium.org> MIME-Version: 1.0 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: robdclark@chromium.org, devicetree@vger.kernel.org, jernej.skrabec@siol.net, jeffrey.l.hugo@gmail.com, linux-arm-msm@vger.kernel.org, jonas@kwiboo.se, Douglas Anderson , dri-devel@lists.freedesktop.org, swboyd@chromium.org, linux-gpio@vger.kernel.org, Laurent Pinchart , bjorn.andersson@linaro.org, linux-kernel@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" The ti-sn65dsi86 MIPI DSI to eDP bridge chip has a dedicated hardware HPD (Hot Plug Detect) pin on it, but it's mostly useless for eDP because of excessive debouncing in hardware. Specifically there is no way to disable the debouncing and for eDP debouncing hurts you because HPD is just used for knowing when the panel is ready, not for detecting physical plug events. Currently the driver in Linux just assumes that nobody has HPD hooked up. It relies on folks setting the "no-hpd" property in the panel node to specify that HPD isn't hooked up and then the panel driver using this to add some worst case delays when turning on the panel. Apparently it's also useful to specify "no-hpd" in the bridge node so that the bridge driver can make sure it's doing the right thing without peeking into the panel [1]. This would be used if anyone ever found it useful to implement support for the HW HPD pin on the bridge. Let's add this property to the bindings. NOTES: - This is somewhat of a backward-incompatible change. All current known users of ti-sn65dsi86 didn't have "no-hpd" specified in the bridge node yet none of them had HPD hooked up. This worked because the current Linux driver just assumed that HPD was never hooked up. We could make it less incompatible by saying that for this bridge it's assumed HPD isn't hooked up _unless_ a property is defined, but "no-hpd" is much more standard and it's unlikely to matter unless someone quickly goes and implements HPD in the driver. - It is sensible to specify "no-hpd" at the bridge chip level and specify "hpd-gpios" at the panel level. That would mean HPD is hooked up to some other GPIO in the system, just not the hardware HPD pin on the bridge chip. [1] https://lore.kernel.org/r/20200417180819.GE5861@pendragon.ideasonboard.com Signed-off-by: Douglas Anderson Reviewed-by: Stephen Boyd Reviewed-by: Linus Walleij Reviewed-by: Laurent Pinchart --- Changes in v5: None Changes in v4: - Tacked on "or is otherwise unusable." to description. Changes in v3: - useful implement => useful to implement Changes in v2: - ("dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd") new for v2. .../devicetree/bindings/display/bridge/ti,sn65dsi86.yaml | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml index 07d26121afca..be10e8cf31e1 100644 --- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml +++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml @@ -28,6 +28,12 @@ properties: maxItems: 1 description: GPIO specifier for GPIO1 pin on bridge (active low). + no-hpd: + type: boolean + description: + Set if the HPD line on the bridge isn't hooked up to anything or is + otherwise unusable. + vccio-supply: description: A 1.8V supply that powers the digital IOs. @@ -213,6 +219,8 @@ examples: clocks = <&rpmhcc RPMH_LN_BB_CLK2>; clock-names = "refclk"; + no-hpd; + ports { #address-cells = <1>; #size-cells = <0>;