From patchwork Tue Apr 26 18:46:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 12827781 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 62A71C433EF for ; Tue, 26 Apr 2022 18:47:17 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 87F9410E24E; Tue, 26 Apr 2022 18:47:16 +0000 (UTC) Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2719B10E24E for ; Tue, 26 Apr 2022 18:47:13 +0000 (UTC) Received: by mail-pf1-x432.google.com with SMTP id b15so18779607pfm.5 for ; Tue, 26 Apr 2022 11:47:13 -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=Ghn6c18H+YaA6ijLmc+sCKaPR5+i6PR27cmfb4hGb6k=; b=oJk6Lr2b2CsnDsmJDhvEfNhpVgCJYJDz9OKmDdOnUG0RWkUIVFR90AdiUHFEtqGF74 3wuuqJtSUuNICYWUR7YJ6HJlGrZ+GvW3nOCacMX4Xv5jPxoeTZl4b9andf9cF5n23ZOE MrkUUD7mwToqaneOIuM/tOvvBYjZ0pJjL5ecM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Ghn6c18H+YaA6ijLmc+sCKaPR5+i6PR27cmfb4hGb6k=; b=cHRPDSkTUnRl8QV4JUvsMVwOMPj8bzz/Fs33JsntO9NasFcrk3BntqxJqdOxA+BbEN qXtT4G5jYtrSKxrnUGtw5SMy2g1rPjyeMzW6cT0sM43kAdl8WEh/m3YMRB6JS7y/eFgO voqai/f34ne3EtSv81cjYYkpHt8xgoJKhzH06zNgw67vhuOKf0HdLcmH8OJYxhongrqA lLAOjhtzwZlwEdgGVrqLWEMl5KaeaPHctlQV7OkKltYmgx7k2aON2SmI9nLMqd4uMpjb Pjgk50kUWHwNh2HVE4+8K3E4bnzAgEESMxBCOLQYUKKflT9LIlIPXu+tX2QXPDB0ENNX m3yw== X-Gm-Message-State: AOAM530OLihbQTJpLB+mq+1EmXKNWJaSVdr91x8nRVUHEY9jdvSp4Gw4 F8AYWrpwkBlthfJmmLaO2lElB0U95YaQJ3TYDH9KKg== X-Google-Smtp-Source: ABdhPJygRrs4Wb7MDL6awvCOxJPZ9BJ00EKhUgHfN+2pY5BZBRj0N8Zv/hgq5JQF+xd54Tlhlhj5ZQ== X-Received: by 2002:aa7:8256:0:b0:4e0:78ad:eb81 with SMTP id e22-20020aa78256000000b004e078adeb81mr25918102pfn.30.1650998832541; Tue, 26 Apr 2022 11:47:12 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:201:8e92:9f42:eda6:c0ee]) by smtp.gmail.com with ESMTPSA id p185-20020a62d0c2000000b0050d1f7c515esm12584396pfg.219.2022.04.26.11.47.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 Apr 2022 11:47:12 -0700 (PDT) From: Douglas Anderson To: dri-devel@lists.freedesktop.org Subject: [PATCH 2/2] drm/probe-helper: For DP, add 640x480 if all other modes are bad Date: Tue, 26 Apr 2022 11:46:51 -0700 Message-Id: <20220426114627.2.I4ac7f55aa446699f8c200a23c10463256f6f439f@changeid> X-Mailer: git-send-email 2.36.0.rc2.479.g8af0fa9b8e-goog In-Reply-To: <20220426114627.1.I2dd93486c6952bd52f2020904de0133970d11b29@changeid> References: <20220426114627.1.I2dd93486c6952bd52f2020904de0133970d11b29@changeid> 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: quic_sbillaka@quicinc.com, Douglas Anderson , Thomas Zimmermann , David Airlie , linux-arm-msm@vger.kernel.org, quic_abhinavk@quicinc.com, quic_khsieh@quicinc.com, dmitry.baryshkov@linaro.org, quic_aravindh@quicinc.com, swboyd@chromium.org, linux-kernel@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" As per Displayport spec section 5.2.1.2 ("Video Timing Format") says that all detachable sinks shall support 640x480 @60Hz as a fail safe mode. A DP compliance test expected us to utilize the above fact when all modes it presented to the DP source were not achievable. It presented only modes that would be achievable with more lanes and/or higher speeds than we had available and expected that when we couldn't do that then we'd fall back to 640x480 even though it didn't advertise this size. In order to pass the compliance test (and also support any users who might fall into a similar situation with their display), we need to add 640x480 into the list of modes. However, we don't want to add 640x480 all the time. Despite the fact that the DP spec says all sinks _shall support_ 640x480, they're not guaranteed to support it _well_. Continuing to read the spec you can see that the display is not required to really treat 640x480 equal to all the other modes. It doesn't need to scale or anything--just display the pixels somehow for failsafe purposes. It should also be noted that it's not hard to find a display hooked up via DisplayPort that _doesn't_ support 640x480 at all. The HP ZR30w screen I'm sitting in front of has a native DP port and doesn't work at 640x480. I also plugged in a tiny 800x480 HDMI display via a DP to HDMI adapter and that screen definitely doesn't support 640x480. As a compromise solution, let's only add the 640x480 mode if: * We're on DP. * All other modes have been pruned. This acknowledges that 640x480 might not be the best mode to use but, since sinks are _supposed_ to support it, we will at least fall back to it if there's nothing else. Note that we _don't_ add higher resolution modes like 1024x768 in this case. We only add those modes for a failed EDID read where we have no idea what's going on. In the case where we've pruned all modes then instead we only want 640x480 which is the only defined "Fail Safe" resolution. This patch originated in response to Kuogee Hsieh's patch [1]. [1] https://lore.kernel.org/r/1650671124-14030-1-git-send-email-quic_khsieh@quicinc.com Signed-off-by: Douglas Anderson Tested-by: Kuogee Hsieh Reviewed-by: Abhinav Kumar Reviewed-by: Dmitry Baryshkov --- drivers/gpu/drm/drm_probe_helper.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c index 819225629010..90cd46cbfec1 100644 --- a/drivers/gpu/drm/drm_probe_helper.c +++ b/drivers/gpu/drm/drm_probe_helper.c @@ -476,7 +476,6 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector, const struct drm_connector_helper_funcs *connector_funcs = connector->helper_private; int count = 0, ret; - bool verbose_prune = true; enum drm_connector_status old_status; struct drm_modeset_acquire_ctx ctx; @@ -556,8 +555,8 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector, DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n", connector->base.id, connector->name); drm_connector_update_edid_property(connector, NULL); - verbose_prune = false; - goto prune; + drm_mode_prune_invalid(dev, &connector->modes, false); + goto exit; } count = (*connector_funcs->get_modes)(connector); @@ -580,9 +579,26 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector, } } -prune: - drm_mode_prune_invalid(dev, &connector->modes, verbose_prune); + drm_mode_prune_invalid(dev, &connector->modes, true); + /* + * Displayport spec section 5.2.1.2 ("Video Timing Format") says that + * all detachable sinks shall support 640x480 @60Hz as a fail safe + * mode. If all modes were pruned, perhaps because they need more + * lanes or a higher pixel clock than available, at least try to add + * in 640x480. + */ + if (list_empty(&connector->modes) && + connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) { + count = drm_add_modes_noedid(connector, 640, 480); + if (_drm_helper_update_and_validate(connector, maxX, maxY, &ctx)) { + drm_modeset_backoff(&ctx); + goto retry; + } + drm_mode_prune_invalid(dev, &connector->modes, true); + } + +exit: drm_modeset_drop_locks(&ctx); drm_modeset_acquire_fini(&ctx);