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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E30F8C6FD18 for ; Tue, 25 Apr 2023 07:40:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233284AbjDYHk3 (ORCPT ); Tue, 25 Apr 2023 03:40:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48096 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233225AbjDYHjr (ORCPT ); Tue, 25 Apr 2023 03:39:47 -0400 Received: from twspam01.aspeedtech.com (twspam01.aspeedtech.com [211.20.114.71]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 393F240EC for ; Tue, 25 Apr 2023 00:39:28 -0700 (PDT) Received: from mail.aspeedtech.com ([192.168.0.24]) by twspam01.aspeedtech.com with ESMTP id 33P7MOxW058183; Tue, 25 Apr 2023 15:22:24 +0800 (GMT-8) (envelope-from jammy_huang@aspeedtech.com) Received: from [192.168.2.115] (192.168.2.115) by TWMBX02.aspeed.com (192.168.0.24) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 25 Apr 2023 15:39:06 +0800 Message-ID: Date: Tue, 25 Apr 2023 15:39:06 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH] drm/ast: Fix modeset failed on DisplayPort To: Thomas Zimmermann , CC: , References: <20230425070330.8520-1-jammy_huang@aspeedtech.com> Content-Language: en-US From: Jammy Huang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [192.168.2.115] X-ClientProxiedBy: TWMBX02.aspeed.com (192.168.0.24) To TWMBX02.aspeed.com (192.168.0.24) X-DNSRBL: X-MAIL: twspam01.aspeedtech.com 33P7MOxW058183 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Thomas, I think DP501 is OK. It doesn't use ioregs in ast_dp501_read_edid(). On 2023/4/25 下午 03:27, Thomas Zimmermann wrote: > Hi > > Am 25.04.23 um 09:03 schrieb Jammy Huang: >> If we switch display and update cursor together, it could lead to >> modeset failed because of concurrent access to IO registers. >> >> Add lock protection in DP's edid access to avoid this problem. > > Thanks for the patch. I thought I fixed this issue already, but that > apparently only happened for SIL164 and VGA. > > What about ast_dp501_connector_helper_get_modes()? Does it require the > locking as well? > >> >> Signed-off-by: Jammy Huang >> --- >>   drivers/gpu/drm/ast/ast_mode.c | 11 +++++++++++ >>   1 file changed, 11 insertions(+) >> >> diff --git a/drivers/gpu/drm/ast/ast_mode.c >> b/drivers/gpu/drm/ast/ast_mode.c >> index 984ec590a7e7..fe5f1fd61361 100644 >> --- a/drivers/gpu/drm/ast/ast_mode.c >> +++ b/drivers/gpu/drm/ast/ast_mode.c >> @@ -1635,6 +1635,8 @@ static int ast_dp501_output_init(struct >> ast_private *ast) >>   static int ast_astdp_connector_helper_get_modes(struct >> drm_connector *connector) >>   { >>       void *edid; >> +    struct drm_device *dev = connector->dev; >> +    struct ast_private *ast = to_ast_private(dev); > > We've meanwhile renamed ast_private to ast_device. Could you please > provide an updated patch for the drm-misc-next tree? > > Best regards > Thomas > >>         int succ; >>       int count; >> @@ -1643,10 +1645,18 @@ static int >> ast_astdp_connector_helper_get_modes(struct drm_connector *connector) >>       if (!edid) >>           goto err_drm_connector_update_edid_property; >>   +    /* >> +     * Protect access to I/O registers from concurrent modesetting >> +     * by acquiring the I/O-register lock. >> +     */ >> +    mutex_lock(&ast->ioregs_lock); >> + >>       succ = ast_astdp_read_edid(connector->dev, edid); >>       if (succ < 0) >>           goto err_kfree; >>   +    mutex_unlock(&ast->ioregs_lock); >> + >>       drm_connector_update_edid_property(connector, edid); >>       count = drm_add_edid_modes(connector, edid); >>       kfree(edid); >> @@ -1654,6 +1664,7 @@ static int >> ast_astdp_connector_helper_get_modes(struct drm_connector *connector) >>       return count; >>     err_kfree: >> +    mutex_unlock(&ast->ioregs_lock); >>       kfree(edid); >>   err_drm_connector_update_edid_property: >>       drm_connector_update_edid_property(connector, NULL); >> >> base-commit: 61d325dcbc05d8fef88110d35ef7776f3ac3f68b > -- Best Regards Jammy