From patchwork Fri May 7 23:39:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lyude Paul X-Patchwork-Id: 12245351 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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 0CEB2C433B4 for ; Fri, 7 May 2021 23:40:32 +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 CF7E561352 for ; Fri, 7 May 2021 23:40:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF7E561352 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.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 C86326E7E2; Fri, 7 May 2021 23:40:30 +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 9A3966E5D2 for ; Fri, 7 May 2021 23:40:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620430828; 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=x1D7g2YRYrTt8SpZQPc/MjeViOMMlZKTfk+6rJTduNU=; b=BL7qj7ZfCe8KqDeVMrARQszmCt1UwtEgrpzwaw7UwIOxgwLhhWouetPB4RL94YNIK8PoZ8 9Uy0vd488bNPRfEsPJYM7ZG3K2h5JryvohAZwpufeg9PvVB05+lEL4CzataDjSQ0/S5ppq lqQ/oRhJevzrUl6n1VGZK7CL8/aFK9k= 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-188-yppPfXZ9OvOmLQMXMpIcLw-1; Fri, 07 May 2021 19:40:27 -0400 X-MC-Unique: yppPfXZ9OvOmLQMXMpIcLw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 68A3A1005E5F; Fri, 7 May 2021 23:40:25 +0000 (UTC) Received: from Ruby.redhat.com (ovpn-112-131.rdu2.redhat.com [10.10.112.131]) by smtp.corp.redhat.com (Postfix) with ESMTP id 92D7B10023AF; Fri, 7 May 2021 23:40:23 +0000 (UTC) From: Lyude Paul To: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, nouveau@lists.freedesktop.org Subject: [RFC v5 6/9] drm/i915/dpcd_bl: Return early in vesa_calc_max_backlight if we can't read PWMGEN_BIT_COUNT Date: Fri, 7 May 2021 19:39:44 -0400 Message-Id: <20210507233947.751846-7-lyude@redhat.com> In-Reply-To: <20210507233947.751846-1-lyude@redhat.com> References: <20210507233947.751846-1-lyude@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 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: Rajeev Nandan , Jani Nikula , David Airlie , open list , greg.depoire@gmail.com, Sean Paul , Rodrigo Vivi Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" If we can't read DP_EDP_PWMGEN_BIT_COUNT in intel_dp_aux_vesa_calc_max_backlight() but do have a valid PWM frequency defined in the VBT, we'll keep going in the function until we inevitably fail on reading DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN. There's not much point in doing this, so just return early. Signed-off-by: Lyude Paul --- drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c index 781c7cd98d75..bf8e4ed56847 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -449,11 +449,14 @@ static u32 intel_dp_aux_vesa_calc_max_backlight(struct intel_connector *connecto int freq, fxp, fxp_min, fxp_max, fxp_actual, f = 1; u8 pn, pn_min, pn_max; - if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT, &pn) == 1) { - pn &= DP_EDP_PWMGEN_BIT_COUNT_MASK; - max_backlight = (1 << pn) - 1; + if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT, &pn) != 1) { + drm_dbg_kms(&i915->drm, "Failed to read pwmgen bit count cap\n"); + return 0; } + pn &= DP_EDP_PWMGEN_BIT_COUNT_MASK; + max_backlight = (1 << pn) - 1; + /* Find desired value of (F x P) * Note that, if F x P is out of supported range, the maximum value or * minimum value will applied automatically. So no need to check that.