linux-kernel - Re: [PATCH 1/6] phy: rockchip-typec: fall back to working in host-mode if extcon is missing.

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Date:   Thu, 01 Mar 2018 10:45:20 +0100
From:   Heiko Stübner <heiko@...ech.de>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     kishon@...com, groeck@...omium.org, gwendal@...omium.org,
        kernel@...labora.com, vicencb@...il.com,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/6] phy: rockchip-typec: fall back to working in host-mode if extcon is missing.

Am Donnerstag, 1. März 2018, 10:24:15 CET schrieb Enric Balletbo i Serra:
> Right now the rockchip typec-phy does fail probing when no extcon is
> detected. Some boards get the cable-state via the extcon interface and
> have this supported, other boards seem to use the fusb302 chip or
> another but the driver currently does not seem to utilize the extcon
> interface to report the cable-state. That's required to detect
> cable-state changes but a missing extcon shouldn't fail to probe,
> instead, should just fall back to working in host-mode if it cannot get
> the extcon.

And of course:
Some boards use no controller at all and just connect the type-c to a
standard USB-A port.

> Fixes: c301b327aea898af ("arm64: dts: rockchip: add usb3-phy otg-port
> support for rk3399") Reported-by: Vicente Bergas <vicencb@...il.com>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> ---
> 
>  drivers/phy/rockchip/phy-rockchip-typec.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/phy/rockchip/phy-rockchip-typec.c
> b/drivers/phy/rockchip/phy-rockchip-typec.c index
> 7492c8978217..3741afab5cd2 100644
> --- a/drivers/phy/rockchip/phy-rockchip-typec.c
> +++ b/drivers/phy/rockchip/phy-rockchip-typec.c
> @@ -782,6 +782,9 @@ static int tcphy_get_mode(struct rockchip_typec_phy
> *tcphy) u8 mode;
>  	int ret;
> 
> +	if (!edev)
> +		return MODE_DFP_USB;
> +
>  	ufp = extcon_get_state(edev, EXTCON_USB);
>  	dp = extcon_get_state(edev, EXTCON_DISP_DP);
> 
> @@ -1115,9 +1118,9 @@ static int rockchip_typec_phy_probe(struct
> platform_device *pdev)
> 
>  	tcphy->extcon = extcon_get_edev_by_phandle(dev, 0);
>  	if (IS_ERR(tcphy->extcon)) {
> -		if (PTR_ERR(tcphy->extcon) != -EPROBE_DEFER)
> -			dev_err(dev, "Invalid or missing extcon\n");
> -		return PTR_ERR(tcphy->extcon);
> +		if (PTR_ERR(tcphy->extcon) == -EPROBE_DEFER)
> +			return PTR_ERR(tcphy->extcon);
> +		tcphy->extcon = NULL;

Do we want to keep a bit of the error handling of extcon, a la

+		if (PTR_ERR(tcphy->extcon) == -ENODEV) {
+			tcphy->extcon = NULL;
+		} else {
+			if (PTR_ERR(tcphy->extcon) != -EPROBE_DEFER)
+				dev_err(dev, "Invalid or extcon\n");
+			return PTR_ERR(tcphy->extcon);
+		}

So only make it NULL, if extcon really reports ENODEV?


Heiko