Re: [PATCH] drm/bridge: parade-ps8640: check return values in ps8640_aux_transfer()

[Tim Gardner]

On 9/24/21 9:26 AM, Tim Gardner wrote:

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.g...@gmail.com>
Cc: Syed Nayyar Waris <syednwa...@gmail.com>
Cc: Andrzej Hajda <a.ha...@samsung.com>
Cc: Neil Armstrong <narmstr...@baylibre.com>
Cc: Robert Foss <robert.f...@linaro.org>
Cc: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
Cc: Jonas Karlman <jo...@kwiboo.se>
Cc: Jernej Skrabec <jernej.skra...@gmail.com>
Cc: David Airlie <airl...@linux.ie>
Cc: Daniel Vetter <dan...@ffwll.ch>
Cc: linux-...@vger.kernel.org
Cc: linux-ker...@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Tim Gardner <tim.gard...@canonical.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);

I forgot to mention this patch is for linux-next next-20210924.

-----------
Tim Gardner
Canonical, Inc