This is a note to let you know that I've just added the patch titled drm/gma500: fix error check to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-gma500-fix-error-check.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 2616f1a9e6db5061c17f4b2af54fd35a9c3f6f4d Author: Tom Rix <trix@xxxxxxxxxx> Date: Wed Aug 5 13:59:11 2020 -0700 drm/gma500: fix error check [ Upstream commit cdd296cdae1af2d27dae3fcfbdf12c5252ab78cf ] Reviewing this block of code in cdv_intel_dp_init() ret = cdv_intel_dp_aux_native_read(gma_encoder, DP_DPCD_REV, ... cdv_intel_edp_panel_vdd_off(gma_encoder); if (ret == 0) { /* if this fails, presume the device is a ghost */ DRM_INFO("failed to retrieve link info, disabling eDP\n"); drm_encoder_cleanup(encoder); cdv_intel_dp_destroy(connector); goto err_priv; } else { The (ret == 0) is not strict enough. cdv_intel_dp_aux_native_read() returns > 0 on success otherwise it is failure. So change to <= Fixes: d112a8163f83 ("gma500/cdv: Add eDP support") Signed-off-by: Tom Rix <trix@xxxxxxxxxx> Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@xxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20200805205911.20927-1-trix@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/gpu/drm/gma500/cdv_intel_dp.c b/drivers/gpu/drm/gma500/cdv_intel_dp.c index d3de377dc857e..25c68e4dc7a53 100644 --- a/drivers/gpu/drm/gma500/cdv_intel_dp.c +++ b/drivers/gpu/drm/gma500/cdv_intel_dp.c @@ -2120,7 +2120,7 @@ cdv_intel_dp_init(struct drm_device *dev, struct psb_intel_mode_device *mode_dev intel_dp->dpcd, sizeof(intel_dp->dpcd)); cdv_intel_edp_panel_vdd_off(gma_encoder); - if (ret == 0) { + if (ret <= 0) { /* if this fails, presume the device is a ghost */ DRM_INFO("failed to retrieve link info, disabling eDP\n"); cdv_intel_dp_encoder_destroy(encoder);