linux-kernel - [PATCH v2 1/2] drm/sun4i: tcon: fix check of tcon->panel null pointer

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Date:   Wed,  3 Oct 2018 16:24:57 +0200
From:   Giulio Benetti <giulio.benetti@...ronovasrl.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     David Airlie <airlied@...ux.ie>, Chen-Yu Tsai <wens@...e.org>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Giulio Benetti <giulio.benetti@...ronovasrl.com>
Subject: [PATCH v2 1/2] drm/sun4i: tcon: fix check of tcon->panel null pointer

At the moment, the check of tcon->panel to be valid is wrong. IS_ERR()
has been used, but that macro doesn't check if tcon->panel pointer is
null or not, but check if tcon->panel is between -1 and -4095(MAX_ERRNO).

Remove IS_ERR() from tcon->panel checking and let "if (tcon->panel)" as
condition to check if it's a pointer not null.

Signed-off-by: Giulio Benetti <giulio.benetti@...ronovasrl.com>
---
Changes V1->V2:
* correct same bug for all same occurences in drm/sun4i folder

 drivers/gpu/drm/sun4i/sun4i_lvds.c | 4 ++--
 drivers/gpu/drm/sun4i/sun4i_rgb.c  | 4 ++--
 drivers/gpu/drm/sun4i/sun4i_tcon.c | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_lvds.c b/drivers/gpu/drm/sun4i/sun4i_lvds.c
index af7dcb6da351..e7eb0d1e17be 100644
--- a/drivers/gpu/drm/sun4i/sun4i_lvds.c
+++ b/drivers/gpu/drm/sun4i/sun4i_lvds.c
@@ -75,7 +75,7 @@ static void sun4i_lvds_encoder_enable(struct drm_encoder *encoder)
 
 	DRM_DEBUG_DRIVER("Enabling LVDS output\n");
 
-	if (!IS_ERR(tcon->panel)) {
+	if (tcon->panel) {
 		drm_panel_prepare(tcon->panel);
 		drm_panel_enable(tcon->panel);
 	}
@@ -88,7 +88,7 @@ static void sun4i_lvds_encoder_disable(struct drm_encoder *encoder)
 
 	DRM_DEBUG_DRIVER("Disabling LVDS output\n");
 
-	if (!IS_ERR(tcon->panel)) {
+	if (tcon->panel) {
 		drm_panel_disable(tcon->panel);
 		drm_panel_unprepare(tcon->panel);
 	}
diff --git a/drivers/gpu/drm/sun4i/sun4i_rgb.c b/drivers/gpu/drm/sun4i/sun4i_rgb.c
index bf068da6b12e..f4a22689eb54 100644
--- a/drivers/gpu/drm/sun4i/sun4i_rgb.c
+++ b/drivers/gpu/drm/sun4i/sun4i_rgb.c
@@ -135,7 +135,7 @@ static void sun4i_rgb_encoder_enable(struct drm_encoder *encoder)
 
 	DRM_DEBUG_DRIVER("Enabling RGB output\n");
 
-	if (!IS_ERR(tcon->panel)) {
+	if (tcon->panel) {
 		drm_panel_prepare(tcon->panel);
 		drm_panel_enable(tcon->panel);
 	}
@@ -148,7 +148,7 @@ static void sun4i_rgb_encoder_disable(struct drm_encoder *encoder)
 
 	DRM_DEBUG_DRIVER("Disabling RGB output\n");
 
-	if (!IS_ERR(tcon->panel)) {
+	if (tcon->panel) {
 		drm_panel_disable(tcon->panel);
 		drm_panel_unprepare(tcon->panel);
 	}
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index c78cd35a1294..e4b3bd0307ef 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -555,7 +555,7 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
 	 * Following code is a way to avoid quirks all around TCON
 	 * and DOTCLOCK drivers.
 	 */
-	if (!IS_ERR(tcon->panel)) {
+	if (tcon->panel) {
 		struct drm_panel *panel = tcon->panel;
 		struct drm_connector *connector = panel->connector;
 		struct drm_display_info display_info = connector->display_info;
-- 
2.17.1