linux-kernel - [PATCH] drm/gma500: fix error check

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Date:   Wed,  5 Aug 2020 13:59:11 -0700
From:   trix@...hat.com
To:     patrik.r.jakobsson@...il.com, airlied@...ux.ie, daniel@...ll.ch,
        airlied@...hat.com, yakui.zhao@...el.com, alan@...ux.intel.com
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Tom Rix <trix@...hat.com>
Subject: [PATCH] drm/gma500: fix error check

From: Tom Rix <trix@...hat.com>

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@...hat.com>
---
 drivers/gpu/drm/gma500/cdv_intel_dp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/gma500/cdv_intel_dp.c b/drivers/gpu/drm/gma500/cdv_intel_dp.c
index f41cbb753bb4..720a767118c9 100644
--- a/drivers/gpu/drm/gma500/cdv_intel_dp.c
+++ b/drivers/gpu/drm/gma500/cdv_intel_dp.c
@@ -2078,7 +2078,7 @@ 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");
 			drm_encoder_cleanup(encoder);
-- 
2.18.1