linux-kernel - Re: [PATCH v3 16/23] platform/chrome: cros_ec_proto: return 0 on getting cmd mask success

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Date:   Wed, 8 Jun 2022 09:20:29 -0700
From:   Guenter Roeck <groeck@...gle.com>
To:     Tzung-Bi Shih <tzungbi@...nel.org>
Cc:     Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        "open list:CHROME HARDWARE PLATFORM SUPPORT" 
        <chrome-platform@...ts.linux.dev>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 16/23] platform/chrome: cros_ec_proto: return 0 on
 getting cmd mask success

On Wed, Jun 8, 2022 at 4:08 AM Tzung-Bi Shih <tzungbi@...nel.org> wrote:
>
> cros_ec_get_host_command_version_mask() used to return value from
> send_command() which is number of available bytes for input payload on
> success (i.e. sizeof(struct ec_response_get_cmd_versions)).
>
> However, the callers don't need to know how many bytes are available.
>
> Don't return number of available bytes.  Instead, return 0 on success;
> otherwise, negative integers on error.
>
> Also remove the unneeded `ver_mask` initialization as the callers should
> take it only if cros_ec_get_host_command_version_mask() returns 0.

Make sure this compiles with W=1. Compilers may think that ver_mask
may be uninitialized when used.

>
> Signed-off-by: Tzung-Bi Shih <tzungbi@...nel.org>

Otherwise

Reviewed-by: Guenter Roeck <groeck@...omium.org>

> ---
> Changes from v2:
> - Separate Kunit test to another patch.
> - Rephrase the commit message.
>
> Changes from v1:
> - Return 0 on success; otherwise, negative intergers.
>
>  drivers/platform/chrome/cros_ec_proto.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
> index efbabdcb31ae..06bc7db1213e 100644
> --- a/drivers/platform/chrome/cros_ec_proto.c
> +++ b/drivers/platform/chrome/cros_ec_proto.c
> @@ -453,6 +453,7 @@ static int cros_ec_get_host_command_version_mask(struct cros_ec_device *ec_dev,
>         if (ret > 0) {
>                 rver = (struct ec_response_get_cmd_versions *)msg->data;
>                 *mask = rver->version_mask;
> +               ret = 0;
>         }
>
>         kfree(msg);
> @@ -469,7 +470,7 @@ static int cros_ec_get_host_command_version_mask(struct cros_ec_device *ec_dev,
>   */
>  int cros_ec_query_all(struct cros_ec_device *ec_dev)
>  {
> -       u32 ver_mask = 0;
> +       u32 ver_mask;
>         int ret;
>
>         /* First try sending with proto v3. */
> @@ -505,9 +506,7 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev)
>                 return -ENOMEM;
>
>         /* Probe if MKBP event is supported */
> -       ret = cros_ec_get_host_command_version_mask(ec_dev,
> -                                                   EC_CMD_GET_NEXT_EVENT,
> -                                                   &ver_mask);
> +       ret = cros_ec_get_host_command_version_mask(ec_dev, EC_CMD_GET_NEXT_EVENT, &ver_mask);
>         if (ret < 0 || ver_mask == 0) {
>                 ec_dev->mkbp_event_supported = 0;
>         } else {
> @@ -517,10 +516,8 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev)
>         }
>
>         /* Probe if host sleep v1 is supported for S0ix failure detection. */
> -       ret = cros_ec_get_host_command_version_mask(ec_dev,
> -                                                   EC_CMD_HOST_SLEEP_EVENT,
> -                                                   &ver_mask);
> -       ec_dev->host_sleep_v1 = (ret >= 0 && (ver_mask & EC_VER_MASK(1)));
> +       ret = cros_ec_get_host_command_version_mask(ec_dev, EC_CMD_HOST_SLEEP_EVENT, &ver_mask);
> +       ec_dev->host_sleep_v1 = (ret == 0 && (ver_mask & EC_VER_MASK(1)));
>
>         /* Get host event wake mask. */
>         ret = cros_ec_get_host_event_wake_mask(ec_dev, &ec_dev->host_event_wake_mask);
> --
> 2.36.1.255.ge46751e96f-goog
>