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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 527E8C433E2 for ; Tue, 8 Sep 2020 19:53:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 20398207DE for ; Tue, 8 Sep 2020 19:53:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599594800; bh=g+Y6OJgjtiO5LtwGG8TxanGgSG6X9uTXvfM7dtbP7T4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=IzlbFr96XvfjbJNa7X35h6X3X5D5gh5vO+oPrM1Z6pioMmcjnSijjj0m/7YPbTcSH S6KwYFYvwAmBJWEE6ECF+KFkSrKnANh/+fdxLk/IUqK2ts/LJZOQsx+bXGdkBXPSDx c84zUM2iDYy4eHdSzcnpwvG+hzUU3y2aZa3QMY0M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730521AbgIHTxE (ORCPT ); Tue, 8 Sep 2020 15:53:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:38038 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730678AbgIHPsF (ORCPT ); Tue, 8 Sep 2020 11:48:05 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D735024824; Tue, 8 Sep 2020 15:44:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599579855; bh=g+Y6OJgjtiO5LtwGG8TxanGgSG6X9uTXvfM7dtbP7T4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rXM6YtazehkDsYIp9Sp/nLSZBtHxgV7rvovVcJCGiUME7BotACMbA5KPfZ4W8io7N RDDgVYz3ydgAyF85YD+U2Er/XPKpGwZ9BJ6Y9cKbDH/W2BOy98l+LgEgR+ZqXWZEG5 zbCso3bcOuLu5iIEd/tPGuXzs/xUYXKaothnu2WA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Christian=20K=C3=B6nig?= , Kai-Heng Feng , Alex Deucher , Sasha Levin Subject: [PATCH 5.4 061/129] drm/radeon: Prefer lower feedback dividers Date: Tue, 8 Sep 2020 17:25:02 +0200 Message-Id: <20200908152232.749853677@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200908152229.689878733@linuxfoundation.org> References: <20200908152229.689878733@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kai-Heng Feng [ Upstream commit fc8c70526bd30733ea8667adb8b8ffebea30a8ed ] Commit 2e26ccb119bd ("drm/radeon: prefer lower reference dividers") fixed screen flicker for HP Compaq nx9420 but breaks other laptops like Asus X50SL. Turns out we also need to favor lower feedback dividers. Users confirmed this change fixes the regression and doesn't regress the original fix. Fixes: 2e26ccb119bd ("drm/radeon: prefer lower reference dividers") BugLink: https://bugs.launchpad.net/bugs/1791312 BugLink: https://bugs.launchpad.net/bugs/1861554 Reviewed-by: Christian König Signed-off-by: Kai-Heng Feng Signed-off-by: Alex Deucher Signed-off-by: Sasha Levin --- drivers/gpu/drm/radeon/radeon_display.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c index f9f74150d0d73..e7c4e06bc7d4f 100644 --- a/drivers/gpu/drm/radeon/radeon_display.c +++ b/drivers/gpu/drm/radeon/radeon_display.c @@ -932,7 +932,7 @@ static void avivo_get_fb_ref_div(unsigned nom, unsigned den, unsigned post_div, /* get matching reference and feedback divider */ *ref_div = min(max(den/post_div, 1u), ref_div_max); - *fb_div = DIV_ROUND_CLOSEST(nom * *ref_div * post_div, den); + *fb_div = max(nom * *ref_div * post_div / den, 1u); /* limit fb divider to its maximum */ if (*fb_div > fb_div_max) { -- 2.25.1