From patchwork Tue Sep 8 15:25:02 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: 264324 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 4E8ECC43461 for ; Tue, 8 Sep 2020 17:27:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A1A920738 for ; Tue, 8 Sep 2020 17:27:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599586034; bh=g+Y6OJgjtiO5LtwGG8TxanGgSG6X9uTXvfM7dtbP7T4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=F3TqHHQHe+eYCsRJQZSFt7WI885KhC/2ue92S4ScOxd/N1ybcIev6XnF8XDgM2+gI sw2qBss/Hl/iJQll/zbEf1HcJMfgmFjTz7mIFErFx8KKK8LFtRpkiH6YQwwXL3vdmv d9m8YDr+XVhtIe6YxY8WO4H2w3ltOup09HHp89zw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731733AbgIHR07 (ORCPT ); Tue, 8 Sep 2020 13:26:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:57298 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731730AbgIHQQ6 (ORCPT ); Tue, 8 Sep 2020 12:16:58 -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_K=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 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 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) {