From 5d583a7e2d92a723e9833604f760517a64f630cc Mon Sep 17 00:00:00 2001 From: Shashank Sharma Date: Thu, 12 Oct 2017 22:10:08 +0530 Subject: [PATCH] drm: Add retries for lspcon mode detection [ 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(-) diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c index 0ef9011..02a5092 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; } -- 2.7.4