From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752565AbdLMB4H (ORCPT ); Tue, 12 Dec 2017 20:56:07 -0500 Received: from omzsmtpe01.verizonbusiness.com ([199.249.25.210]:15945 "EHLO omzsmtpe01.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752077AbdLMBzk (ORCPT ); Tue, 12 Dec 2017 20:55:40 -0500 From: alexander.levin@verizon.com Cc: Shashank Sharma , Ville Syrjala , Imre Deak , Jani Nikula , Jani Nikula , alexander.levin@verizon.com X-Host: mariner.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 4.14 02/60] drm: Add retries for lspcon mode detection Thread-Topic: [PATCH AUTOSEL for 4.14 02/60] drm: Add retries for lspcon mode detection Thread-Index: AQHTc7VoVzE5ME6Vg0CcRajNQbc8eQ== Date: Wed, 13 Dec 2017 01:55:10 +0000 Message-ID: <20171213015455.6455-2-alexander.levin@verizon.com> References: <20171213015455.6455-1-alexander.levin@verizon.com> In-Reply-To: <20171213015455.6455-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vBD1uCRk014591 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 --- drivers/gpu/drm/drm_dp_dual_mode_helper.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c index 0ef9011a1856..02a50929af67 100644 --- 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_adapter *adapter, { 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_adapter *adapter, } /* 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; } -- 2.11.0