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=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 E3798C433E2 for ; Tue, 8 Sep 2020 17:58:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B09B4206E7 for ; Tue, 8 Sep 2020 17:58:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599587891; bh=XHlAjR9qSwET0U1pVWZAfuClY0y2XU1KBVQksFFB5TQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Lt6NA6IUtKqYnjjMj1wSDWoG5vThfR+t69rO8uL831+CZ0MoPZXl6RadpUFBp428p 14/BMc4kHWG31tMDc+6iKw2v3SauIUVmvFnMZgZJZ2jL0YcLB8T0vt2gAs5DJPY8MF b0wgev1i2dRba4Xv9dDUnHkFpJ0jh3EZ4A7LGXlA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732210AbgIHR6I (ORCPT ); Tue, 8 Sep 2020 13:58:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:56086 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731564AbgIHQMr (ORCPT ); Tue, 8 Sep 2020 12:12:47 -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 AE09B24882; Tue, 8 Sep 2020 15:52:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599580333; bh=XHlAjR9qSwET0U1pVWZAfuClY0y2XU1KBVQksFFB5TQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DEdh4DKnAV2zHUucryy6Ya2YYEM5FGa1OeNu0VUo1YMXgQUjjbhRX938JNavT5cs9 LPXeCmikTd/RrXPCBoRUKxH8o1nMtqjmDMlHBIKryKcde5GBuzzJeeNey9d/lpUhbM Q6ITD1e6zw6lBK3acc5IGzhT+QLPZ4NmAb1apGWU= 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 4.14 33/65] drm/radeon: Prefer lower feedback dividers Date: Tue, 8 Sep 2020 17:26:18 +0200 Message-Id: <20200908152218.744293413@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200908152217.022816723@linuxfoundation.org> References: <20200908152217.022816723@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 b2334349799d1..f1de68340944b 100644 --- a/drivers/gpu/drm/radeon/radeon_display.c +++ b/drivers/gpu/drm/radeon/radeon_display.c @@ -928,7 +928,7 @@ 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