Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758134AbdLVJcC (ORCPT ); Fri, 22 Dec 2017 04:32:02 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:39372 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965328AbdLVJCw (ORCPT ); Fri, 22 Dec 2017 04:02:52 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ville Syrjala , Imre Deak , Jani Nikula , Dave Airlie , Shashank Sharma , Jani Nikula , Sasha Levin Subject: [PATCH 4.14 102/159] drm: Add retries for lspcon mode detection Date: Fri, 22 Dec 2017 09:46:27 +0100 Message-Id: <20171222084629.257692497@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171222084623.668990192@linuxfoundation.org> References: <20171222084623.668990192@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2696 Lines: 77 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shashank Sharma [ Upstream commit f687e25a7a245952349f1f9f9cc238ac5a3be258 ] >From the CI builds, its been observed that during a driver reload/insert, dp dual mode read function sometimes fails to read from LSPCON device over i2c-over-aux channel. This patch: - adds some delay and few retries, allowing a scope for these devices to settle down and respond. - changes one error log's level from ERROR->DEBUG as we want to call it an error only after all the retries are exhausted. V2: Addressed review comments from Jani (for loop for retry) V3: Addressed review comments from Imre (break on partial read too) V3: Addressed review comments from Ville/Imre (Add the retries exclusively for LSPCON, not for all dp_dual_mode devices) V4: Added r-b from Imre, sending it to dri-devel (Jani) Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102294 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102295 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102359 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103186 Cc: Ville Syrjala Cc: Imre Deak Cc: Jani Nikula Reviewed-by: Imre Deak Acked-by: Dave Airlie Signed-off-by: Shashank Sharma Signed-off-by: Jani Nikula Link: https://patchwork.freedesktop.org/patch/msgid/1507826408-19322-1-git-send-email-shashank.sharma@intel.com Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_dp_dual_mode_helper.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c @@ -410,6 +410,7 @@ int drm_lspcon_get_mode(struct i2c_adapt { u8 data; int ret = 0; + int retry; if (!mode) { DRM_ERROR("NULL input\n"); @@ -417,10 +418,19 @@ int drm_lspcon_get_mode(struct i2c_adapt } /* Read Status: i2c over aux */ - ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_LSPCON_CURRENT_MODE, - &data, sizeof(data)); + for (retry = 0; retry < 6; retry++) { + if (retry) + usleep_range(500, 1000); + + ret = drm_dp_dual_mode_read(adapter, + DP_DUAL_MODE_LSPCON_CURRENT_MODE, + &data, sizeof(data)); + if (!ret) + break; + } + if (ret < 0) { - DRM_ERROR("LSPCON read(0x80, 0x41) failed\n"); + DRM_DEBUG_KMS("LSPCON read(0x80, 0x41) failed\n"); return -EFAULT; }