linux-kernel - Re: [PATCH] drm/bridge: anx7625: Fix null vs IS_ERR() checking in anx7625_register_i2c_dummy

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Date:   Tue, 4 Jan 2022 15:29:00 +0100
From:   Robert Foss <robert.foss@...aro.org>
To:     Miaoqian Lin <linmq006@...il.com>
Cc:     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>,
        Pi-Hsun Shih <pihsun@...omium.org>,
        Xin Ji <xji@...logixsemi.com>, Sam Ravnborg <sam@...nborg.org>,
        Tzung-Bi Shih <tzungbi@...gle.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Nicolas Boichat <drinkcat@...omium.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: anx7625: Fix null vs IS_ERR() checking in anx7625_register_i2c_dummy_clients

Hey Miaoqian,

Thanks for submitting this fix.

On Wed, 22 Dec 2021 at 09:33, Miaoqian Lin <linmq006@...il.com> wrote:
>
> Since i2c_new_client_device() function return error pointers.
> The i2c_new_dummy_device() function does not return NULL, It returns error
> pointers too. Using IS_ERR() to check the return value to fix this.
>
> Fixes: 8bdfc5dae4e3("drm/bridge: anx7625: Add anx7625 MIPI DSI/DPI to DP")
> Signed-off-by: Miaoqian Lin <linmq006@...il.com>
> ---
>  drivers/gpu/drm/bridge/analogix/anx7625.c | 32 ++++++++++++++++-------
>  1 file changed, 23 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> index 1a871f6b6822..eb72aa6aedd6 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> @@ -1637,40 +1637,54 @@ static const struct drm_bridge_funcs anx7625_bridge_funcs = {
>  static int anx7625_register_i2c_dummy_clients(struct anx7625_data *ctx,
>                                               struct i2c_client *client)
>  {
> +       int err = 0;
> +
>         ctx->i2c.tx_p0_client = i2c_new_dummy_device(client->adapter,
>                                                      TX_P0_ADDR >> 1);
> -       if (!ctx->i2c.tx_p0_client)
> -               return -ENOMEM;
> +       if (IS_ERR(ctx->i2c.tx_p0_client))
> +               return PTR_ERR(ctx->i2c.tx_p0_client);
>
>         ctx->i2c.tx_p1_client = i2c_new_dummy_device(client->adapter,
>                                                      TX_P1_ADDR >> 1);
> -       if (!ctx->i2c.tx_p1_client)
> +       if (IS_ERR(ctx->i2c.tx_p1_client)) {
> +               err = PTR_ERR(ctx->i2c.tx_p1_client);
>                 goto free_tx_p0;
> +       }
>
>         ctx->i2c.tx_p2_client = i2c_new_dummy_device(client->adapter,
>                                                      TX_P2_ADDR >> 1);
> -       if (!ctx->i2c.tx_p2_client)
> +       if (IS_ERR(ctx->i2c.tx_p2_client)) {
> +               err = PTR_ERR(ctx->i2c.tx_p2_client);
>                 goto free_tx_p1;
> +       }
>
>         ctx->i2c.rx_p0_client = i2c_new_dummy_device(client->adapter,
>                                                      RX_P0_ADDR >> 1);
> -       if (!ctx->i2c.rx_p0_client)
> +       if (IS_ERR(ctx->i2c.rx_p0_client)) {
> +               err = PTR_ERR(ctx->i2c.rx_p0_client);
>                 goto free_tx_p2;
> +       }
>
>         ctx->i2c.rx_p1_client = i2c_new_dummy_device(client->adapter,
>                                                      RX_P1_ADDR >> 1);
> -       if (!ctx->i2c.rx_p1_client)
> +       if (IS_ERR(ctx->i2c.rx_p1_client)) {
> +               err = PTR_ERR(ctx->i2c.rx_p1_client);
>                 goto free_rx_p0;
> +       }
>
>         ctx->i2c.rx_p2_client = i2c_new_dummy_device(client->adapter,
>                                                      RX_P2_ADDR >> 1);
> -       if (!ctx->i2c.rx_p2_client)
> +       if (IS_ERR(ctx->i2c.rx_p2_client)) {
> +               err = PTR_ERR(ctx->i2c.rx_p2_client);
>                 goto free_rx_p1;
> +       }
>
>         ctx->i2c.tcpc_client = i2c_new_dummy_device(client->adapter,
>                                                     TCPC_INTERFACE_ADDR >> 1);
> -       if (!ctx->i2c.tcpc_client)
> +       if (IS_ERR(ctx->i2c.tcpc_client)) {
> +               err = PTR_ERR(ctx->i2c.tcpc_client);
>                 goto free_rx_p2;
> +       }
>
>         return 0;
>
> @@ -1687,7 +1701,7 @@ static int anx7625_register_i2c_dummy_clients(struct anx7625_data *ctx,
>  free_tx_p0:
>         i2c_unregister_device(ctx->i2c.tx_p0_client);
>
> -       return -ENOMEM;
> +       return err;
>  }
>
>  static void anx7625_unregister_i2c_dummy_clients(struct anx7625_data *ctx)
> --
> 2.17.1
>

Reviewed-by: Robert Foss <robert.foss@...aro.org>