From patchwork Tue Sep 8 15:26:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 264302 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 214B1C43461 for ; Tue, 8 Sep 2020 17:58:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFF6B2074B for ; Tue, 8 Sep 2020 17:58:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599587924; bh=XHlAjR9qSwET0U1pVWZAfuClY0y2XU1KBVQksFFB5TQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Vj9VabZ38gYIjODFXD8lQ9WLaWdNSxqwagoiwNYKjy5wr/mIYgDyDTs1PrIdOkAiz T5pYDK+xXtpHGNFvN6dJeuwBkeqjA9TwpvsKzHrAWXGrzemZOlCbJPK1JA7vWcNPnM nWhz6QWERmzttlfEqNkMURsXtgOYsMZcLzaR1a8M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731566AbgIHR6H (ORCPT ); Tue, 8 Sep 2020 13:58:07 -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_K=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 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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) {