drm/i915: Increase LSPCON timeout

commit 299c2a904b1e8d5096d4813df6371357d97a6cd1 upstream.

100 ms is not enough time for the LSPCON adapter on Intel NUC devices to
settle. This causes dropped display modes at boot or screen reconfiguration.
Empirical testing can reproduce the error up to a timeout of 190 ms. Basic
boot and stress testing at 200 ms has not (yet) failed.

Increase timeout to 400 ms to get some margin of error.

Changes from v1:
The initial suggestion of 1000 ms was lowered due to concerns about delaying
valid timeout cases.
Update patch metadata.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107503
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1570392
Fixes: 357c0ae9198a ("drm/i915/lspcon: Wait for expected LSPCON mode to settle")
Cc: Shashank Sharma <shashank.sharma@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: <stable@vger.kernel.org> # v4.11+
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Fredrik Schön <fredrik.schon@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180817200728.8154-1-fredrik.schon@gmail.com
(cherry picked from commit 59f1c8ab30d6f9042562949f42cbd3f3cf69de94)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Fredrik Schön <fredrik.schon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/i915/intel_lspcon.c b/drivers/gpu/drm/i915/intel_lspcon.c
index beb9baaf2f2e4e573956f1ea842c2963dce95bd7..f71fef10ecc6180a3fc8835bb864dbf24771f705 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lspcon.c
+++ b/drivers/gpu/drm/i915/intel_lspcon.c
@@ -75,7 +75,7 @@ static enum drm_lspcon_mode lspcon_wait_mode(struct intel_lspcon *lspcon,
                      lspcon_mode_name(mode));
 
        wait_for((current_mode = lspcon_get_current_mode(lspcon)) == mode ||
-                current_mode == DRM_LSPCON_MODE_INVALID, 100);
+                current_mode == DRM_LSPCON_MODE_INVALID, 400);
        if (current_mode != mode)
                DRM_DEBUG_KMS("LSPCON mode hasn't settled\n");