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

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Date:   Mon, 11 Oct 2021 12:07:55 +0200
From:   Robert Foss <robert.foss@...aro.org>
To:     Tim Gardner <tim.gardner@...onical.com>
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        William Breathitt Gray <vilhelm.gray@...il.com>,
        Syed Nayyar Waris <syednwaris@...il.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        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 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/bridge: parade-ps8640: check return values in ps8640_aux_transfer()

Hey Tim,

Thanks for submitting this.

I'm seeing some checkpatch --strict warnings. Could you fix them and
resubmit the series?

On Fri, 24 Sept 2021 at 17:26, Tim Gardner <tim.gardner@...onical.com> 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

Checkpatch is unhappy about the length of this line.

> 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));

Align to open parenthesis.

> +       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
>