From patchwork Fri Nov 5 18:33:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lyude Paul X-Patchwork-Id: 12605213 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4938EC433EF for ; Fri, 5 Nov 2021 18:34:28 +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 19D6161131 for ; Fri, 5 Nov 2021 18:34:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 19D6161131 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9785F6EC85; Fri, 5 Nov 2021 18:34:23 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 457376EC85 for ; Fri, 5 Nov 2021 18:34:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1636137259; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0/G6y34JOTC7UqNDqWGUgS2eZXF3BvIhBAU3/+T9uZs=; b=gd9XK40dK2lsnIV3Js9EsXE+R9fJ05483MOqcwpHUdfTDLlgOlP/4r+TO35APR72P1Mxo4 xDhwo/iLhPMpclbODHlbEwzO6YmgrkwVq5q2npMvOL3nE1DaHXULOR9eqqvbDoV82aZdOg v5GYTVdiTU8mCIaE4LQ/89Js3MD4fOI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-602-558qMmg2NmON34f9YiwcaQ-1; Fri, 05 Nov 2021 14:34:16 -0400 X-MC-Unique: 558qMmg2NmON34f9YiwcaQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 997621B2C983; Fri, 5 Nov 2021 18:34:14 +0000 (UTC) Received: from emerald.lyude.net (unknown [10.22.16.200]) by smtp.corp.redhat.com (Postfix) with ESMTP id B3CD75FC13; Fri, 5 Nov 2021 18:34:11 +0000 (UTC) From: Lyude Paul To: dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, intel-gfx@lists.freedesktop.org Subject: [PATCH v5 3/5] drm/dp: Don't read back backlight mode in drm_edp_backlight_enable() Date: Fri, 5 Nov 2021 14:33:40 -0400 Message-Id: <20211105183342.130810-4-lyude@redhat.com> In-Reply-To: <20211105183342.130810-1-lyude@redhat.com> References: <20211105183342.130810-1-lyude@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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: Thomas Zimmermann , David Airlie , open list , Rodrigo Vivi Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" As it turns out, apparently some machines will actually leave additional backlight functionality like dynamic backlight control on before the OS loads. Currently we don't take care to disable unsupported features when writing back the backlight mode, which can lead to some rather strange looking behavior when adjusting the backlight. So, let's fix this by just not reading back the current backlight mode on initial enable. I don't think there should really be any downsides to this, and this will ensure we don't leave any unsupported functionality enabled. This should fix at least one (but not all) of the issues seen with DPCD backlight support on fi-bdw-samus v5: * Just avoid reading back DPCD register - Doug Anderson Signed-off-by: Lyude Paul Fixes: 867cf9cd73c3 ("drm/dp: Extract i915's eDP backlight code into DRM helpers") Reviewed-by: Douglas Anderson --- drivers/gpu/drm/drm_dp_helper.c | 40 ++++++++++----------------------- 1 file changed, 12 insertions(+), 28 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index ada0a1ff262d..af2aad2f4725 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -3363,27 +3363,13 @@ int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct drm_edp_backli const u16 level) { int ret; - u8 dpcd_buf, new_dpcd_buf; + u8 dpcd_buf = DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD; - ret = drm_dp_dpcd_readb(aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf); - if (ret != 1) { - drm_dbg_kms(aux->drm_dev, - "%s: Failed to read backlight mode: %d\n", aux->name, ret); - return ret < 0 ? ret : -EIO; - } - - new_dpcd_buf = dpcd_buf; - - if ((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) != DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) { - new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK; - new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD; - - if (bl->pwmgen_bit_count) { - ret = drm_dp_dpcd_writeb(aux, DP_EDP_PWMGEN_BIT_COUNT, bl->pwmgen_bit_count); - if (ret != 1) - drm_dbg_kms(aux->drm_dev, "%s: Failed to write aux pwmgen bit count: %d\n", - aux->name, ret); - } + if (bl->pwmgen_bit_count) { + ret = drm_dp_dpcd_writeb(aux, DP_EDP_PWMGEN_BIT_COUNT, bl->pwmgen_bit_count); + if (ret != 1) + drm_dbg_kms(aux->drm_dev, "%s: Failed to write aux pwmgen bit count: %d\n", + aux->name, ret); } if (bl->pwm_freq_pre_divider) { @@ -3393,16 +3379,14 @@ int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct drm_edp_backli "%s: Failed to write aux backlight frequency: %d\n", aux->name, ret); else - new_dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE; + dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE; } - if (new_dpcd_buf != dpcd_buf) { - ret = drm_dp_dpcd_writeb(aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf); - if (ret != 1) { - drm_dbg_kms(aux->drm_dev, "%s: Failed to write aux backlight mode: %d\n", - aux->name, ret); - return ret < 0 ? ret : -EIO; - } + ret = drm_dp_dpcd_writeb(aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf); + if (ret != 1) { + drm_dbg_kms(aux->drm_dev, "%s: Failed to write aux backlight mode: %d\n", + aux->name, ret); + return ret < 0 ? ret : -EIO; } ret = drm_edp_backlight_set_level(aux, bl, level);