Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20221220055954.11197-1-zhouruihai@huaqin.corp-partner.google.com>
In-Reply-To: <20221220055954.11197-1-zhouruihai@huaqin.corp-partner.google.com>
From:   Guenter Roeck <groeck@google.com>
Date:   Tue, 20 Dec 2022 07:09:40 -0800
Message-ID: <CABXOdTeJuFn-23OiTshJTQWMBvkiqOXUh6S8z354eEPzj+q4Ew@mail.gmail.com>
Subject: Re: [PATCH] platform/chrome: cros_ec_typec: deferred probe when typec
 count mismatch
To:     Ruihai Zhou <zhouruihai@huaqin.corp-partner.google.com>
Cc:     pmalani@chromium.org, bleung@chromium.org, groeck@chromium.org,
        knoxchiou@chromium.org, weishunc@chromium.org,
        chrome-platform@lists.linux.dev, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Dec 19, 2022 at 10:00 PM Ruihai Zhou
<zhouruihai@huaqin.corp-partner.google.com> wrote:
>
> The kernel bootup is much faster with normal mode. In this case,
> there is a chance that the cros-ec-typec module get the actual typec
> port counts but not accurate from ec before ec is able to setup it.
> It will block the HDMI mux function.
> Hence, return -EPROBE_DEFER to put the device onto the deferred probe
> list when the typec count mismatch between ec and node.
>
> Signed-off-by: Ruihai Zhou <zhouruihai@huaqin.corp-partner.google.com>
> ---
>  drivers/platform/chrome/cros_ec_typec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> index 59de4ce01fab..d821501e875c 100644
> --- a/drivers/platform/chrome/cros_ec_typec.c
> +++ b/drivers/platform/chrome/cros_ec_typec.c
> @@ -382,7 +382,7 @@ static int cros_typec_init_ports(struct cros_typec_data *typec)
>
>         if (nports > typec->num_ports) {
>                 dev_err(dev, "More ports listed than can be supported.\n");
> -               return -EINVAL;
> +               return -EPROBE_DEFER;

I think that is problematic. It might as well be that nports >
EC_USB_PD_MAX_PORTS.

Is this really seen in the field ? The EC should never report a wrong
(random) number of ports. If it is not ready, there should be _some_
indication that it isn't ready. Does it really report a more or less
random number in this case ?

Guenter

>         }
>
>         /* DT uses "reg" to specify port number. */
> --
> 2.17.1
>