linux-kernel - Re: [PATCH] platform/chrome: cros_ec

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Date:   Mon, 4 Apr 2022 18:57:22 -0700
From:   Guenter Roeck <groeck@...gle.com>
To:     Akihiko Odaki <akihiko.odaki@...il.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        chrome-platform@...ts.linux.dev,
        Prashant Malani <pmalani@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH] platform/chrome: cros_ec_typec: Check for EC driver

On Sun, Apr 3, 2022 at 9:11 PM Akihiko Odaki <akihiko.odaki@...il.com> wrote:
>
> The EC driver may not be initialized when cros_typec_probe is called,
> particulary when CONFIG_CROS_EC_CHARDEV=m.
>

Does this cause a crash ? If so, do you have a crash log ?

Reason for asking is that I saw the following crash, and it would be
good to know if the problem is the same.

<1>[    6.651137] #PF: error_code(0x0002) - not-present page
<6>[    6.651139] PGD 0 P4D 0
<4>[    6.651143] Oops: 0002 [#1] PREEMPT SMP NOPTI
<4>[    6.651146] CPU: 0 PID: 1656 Comm: udevd Tainted: G     U
    5.4.163-17384-g99ca1c60d20c #1
<4>[    6.651147] Hardware name: HP Lantis/Lantis, BIOS
Google_Lantis.13606.204.0 05/26/2021
<4>[    6.651152] RIP: 0010:mutex_lock+0x2b/0x3c
...
<4>[    6.651174] Call Trace:
<4>[    6.651180]  cros_ec_cmd_xfer+0x22/0xc1
<4>[    6.651183]  cros_ec_cmd_xfer_status+0x19/0x59
<4>[    6.651185]  cros_ec_command+0x82/0xc3
<4>[    6.651189]  cros_typec_probe+0x8a/0x5a2 [cros_ec_typec]

> Signed-off-by: Akihiko Odaki <akihiko.odaki@...il.com>

Not sure if this is the best solution, but I don't know a better one.

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

> ---
>  drivers/platform/chrome/cros_ec_typec.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> index 4bd2752c0823..7cb2e35c4ded 100644
> --- a/drivers/platform/chrome/cros_ec_typec.c
> +++ b/drivers/platform/chrome/cros_ec_typec.c
> @@ -1084,6 +1084,9 @@ static int cros_typec_probe(struct platform_device *pdev)
>         }
>
>         ec_dev = dev_get_drvdata(&typec->ec->ec->dev);
> +       if (!ec_dev)
> +               return -EPROBE_DEFER;
> +
>         typec->typec_cmd_supported = cros_ec_check_features(ec_dev, EC_FEATURE_TYPEC_CMD);
>         typec->needs_mux_ack = cros_ec_check_features(ec_dev, EC_FEATURE_TYPEC_MUX_REQUIRE_AP_ACK);
>
> --
> 2.35.1
>