linux-kernel - Re: [PATCH] usb: typec: fsa4480: Relax CHIP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <D3JBLQVFQ7KB.6CGONK66O4XE@fairphone.com>
Date: Sun, 18 Aug 2024 22:30:00 +0200
From: "Luca Weiss" <luca.weiss@...rphone.com>
To: "Luca Weiss" <luca.weiss@...rphone.com>, "Heikki Krogerus"
 <heikki.krogerus@...ux.intel.com>, "Greg Kroah-Hartman"
 <gregkh@...uxfoundation.org>, "Konrad Dybcio" <konrad.dybcio@...aro.org>,
 "Dmitry Baryshkov" <dmitry.baryshkov@...aro.org>, "Caleb Connolly"
 <caleb.connolly@...aro.org>
Cc: <~postmarketos/upstreaming@...ts.sr.ht>, <phone-devel@...r.kernel.org>,
 <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <linux-arm-msm@...r.kernel.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH] usb: typec: fsa4480: Relax CHIP_ID check

On Sun Aug 18, 2024 at 10:21 PM CEST, Luca Weiss wrote:
> Some FSA4480-compatible chips like the OCP96011 used on Fairphone 5
> return 0x00 from the CHIP_ID register. Handle that gracefully and only
> fail probe when the I2C read has failed.
>
> With this the dev_dbg will print 0 but otherwise continue working.
>
>   [    0.251581] fsa4480 1-0042: Found FSA4480 v0.0 (Vendor ID = 0)

Short appendix: just checked the OCP96011 datasheet and it does mention
register 00H being "Device ID" and "Reset Value" being 0x00 so that's
expected behavior on this specific chip.

Regards
Luca

>
> Cc: stable@...r.kernel.org
> Fixes: e885f5f1f2b4 ("usb: typec: fsa4480: Check if the chip is really there")
> Signed-off-by: Luca Weiss <luca.weiss@...rphone.com>
> ---
>  drivers/usb/typec/mux/fsa4480.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/typec/mux/fsa4480.c b/drivers/usb/typec/mux/fsa4480.c
> index cd235339834b..f71dba8bf07c 100644
> --- a/drivers/usb/typec/mux/fsa4480.c
> +++ b/drivers/usb/typec/mux/fsa4480.c
> @@ -274,7 +274,7 @@ static int fsa4480_probe(struct i2c_client *client)
>  		return dev_err_probe(dev, PTR_ERR(fsa->regmap), "failed to initialize regmap\n");
>  
>  	ret = regmap_read(fsa->regmap, FSA4480_DEVICE_ID, &val);
> -	if (ret || !val)
> +	if (ret)
>  		return dev_err_probe(dev, -ENODEV, "FSA4480 not found\n");
>  
>  	dev_dbg(dev, "Found FSA4480 v%lu.%lu (Vendor ID = %lu)\n",
>
> ---
> base-commit: ccdbf91fdf5a71881ef32b41797382c4edd6f670
> change-id: 20240818-fsa4480-chipid-fix-2c7cf5810135
>
> Best regards,