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 F27C3C7EE23 for ; Wed, 24 May 2023 02:31:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236337AbjEXCbI (ORCPT ); Tue, 23 May 2023 22:31:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56182 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229991AbjEXCbF (ORCPT ); Tue, 23 May 2023 22:31:05 -0400 X-Greylist: delayed 64 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Tue, 23 May 2023 19:31:02 PDT Received: from mail.aspeedtech.com (mail.aspeedtech.com [211.20.114.72]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 521B6C2 for ; Tue, 23 May 2023 19:31:02 -0700 (PDT) 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; Wed, 24 May 2023 10:29:56 +0800 Message-ID: <1e4ca9bc-0e39-2708-8da8-b402139fe7ff@aspeedtech.com> Date: Wed, 24 May 2023 10:29:57 +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 From: Jammy Huang To: Thomas Zimmermann , CC: , References: <20230425070330.8520-1-jammy_huang@aspeedtech.com> Content-Language: en-US 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) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Thomas, Do you have other suggestion for this patch?? Please kindly advise. On 2023/4/25 下午 03:39, Jammy Huang wrote: > 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