linux-kernel - [PATCH] drm/bridge: parade-ps8640: check return values in ps8640_aux

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Date:   Fri, 24 Sep 2021 09:26:07 -0600
From:   Tim Gardner <tim.gardner@...onical.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     tim.gardner@...onical.com,
        William Breathitt Gray <vilhelm.gray@...il.com>,
        Syed Nayyar Waris <syednwaris@...il.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/bridge: parade-ps8640: check return values in ps8640_aux_transfer()

Coverity complains of an unused return code:

CID 120459 (#1 of 1): Unchecked return value (CHECKED_RETURN)
7. check_return: Calling regmap_bulk_write without checking return value (as is
done elsewhere 199 out of 291 times).
204        regmap_bulk_write(map, PAGE0_SWAUX_ADDR_7_0, addr_len,
205                          ARRAY_SIZE(addr_len));

While I was at it I noticed 2 other places where return codes were not being
used, or used incorrectly (which is a real bug).

Fix these errors by correctly using the returned error codes.

Cc: William Breathitt Gray <vilhelm.gray@...il.com>
Cc: Syed Nayyar Waris <syednwaris@...il.com>
Cc: Andrzej Hajda <a.hajda@...sung.com>
Cc: Neil Armstrong <narmstrong@...libre.com>
Cc: Robert Foss <robert.foss@...aro.org>
Cc: Laurent Pinchart <Laurent.pinchart@...asonboard.com>
Cc: Jonas Karlman <jonas@...boo.se>
Cc: Jernej Skrabec <jernej.skrabec@...il.com>
Cc: David Airlie <airlied@...ux.ie>
Cc: Daniel Vetter <daniel@...ll.ch>
Cc: linux-iio@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Cc: dri-devel@...ts.freedesktop.org
Signed-off-by: Tim Gardner <tim.gardner@...onical.com>
---
 drivers/gpu/drm/bridge/parade-ps8640.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
index 3aaa90913bf8..591da962970a 100644
--- a/drivers/gpu/drm/bridge/parade-ps8640.c
+++ b/drivers/gpu/drm/bridge/parade-ps8640.c
@@ -201,8 +201,12 @@ static ssize_t ps8640_aux_transfer(struct drm_dp_aux *aux,
 	addr_len[PAGE0_SWAUX_LENGTH - base] = (len == 0) ? SWAUX_NO_PAYLOAD :
 					      ((len - 1) & SWAUX_LENGTH_MASK);
 
-	regmap_bulk_write(map, PAGE0_SWAUX_ADDR_7_0, addr_len,
+	ret = regmap_bulk_write(map, PAGE0_SWAUX_ADDR_7_0, addr_len,
 			  ARRAY_SIZE(addr_len));
+	if (ret) {
+		DRM_DEV_ERROR(dev, "failed to bulk write ADDR_7_0: %d\n", ret);
+		return ret;
+	}
 
 	if (len && (request == DP_AUX_NATIVE_WRITE ||
 		    request == DP_AUX_I2C_WRITE)) {
@@ -218,13 +222,17 @@ static ssize_t ps8640_aux_transfer(struct drm_dp_aux *aux,
 		}
 	}
 
-	regmap_write(map, PAGE0_SWAUX_CTRL, SWAUX_SEND);
+	ret = regmap_write(map, PAGE0_SWAUX_CTRL, SWAUX_SEND);
+	if (ret) {
+		DRM_DEV_ERROR(dev, "failed to write SEND: %d\n", ret);
+		return ret;
+	}
 
 	/* Zero delay loop because i2c transactions are slow already */
 	regmap_read_poll_timeout(map, PAGE0_SWAUX_CTRL, data,
 				 !(data & SWAUX_SEND), 0, 50 * 1000);
 
-	regmap_read(map, PAGE0_SWAUX_STATUS, &data);
+	ret = regmap_read(map, PAGE0_SWAUX_STATUS, &data);
 	if (ret) {
 		DRM_DEV_ERROR(dev, "failed to read PAGE0_SWAUX_STATUS: %d\n",
 			      ret);
-- 
2.33.0