linux-kernel - Re: [PATCH v2] usb: serial: Repair FTDI FT232R bricked eeprom

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Date:   Thu, 10 Sep 2020 05:02:34 +0200
From:   Oliver Neukum <oneukum@...e.de>
To:     James Hilliard <james.hilliard1@...il.com>,
        linux-usb@...r.kernel.org
Cc:     Johan Hovold <johan@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, Russ Dill <Russ.Dill@...il.com>,
        Hector Martin <hector@...cansoft.com>
Subject: Re: [PATCH v2] usb: serial: Repair FTDI FT232R bricked eeprom

Am Mittwoch, den 09.09.2020, 13:34 -0600 schrieb James Hilliard:
> This patch detects and reverses the effects of the malicious FTDI
> Windows driver version 2.12.00(FTDIgate).

Hi,

this raises questions.
Should we do this unconditionally without asking?
Does this belong into kernel space?

> +static int ftdi_repair_brick(struct usb_serial_port *port)
> +{
> +	struct ftdi_private *priv = usb_get_serial_port_data(port);
> +	int orig_latency;
> +	int rv;
> +	u16 *eeprom_data;
> +	u16 checksum;
> +	int eeprom_size;
> +	int result;
> +
> +	switch (priv->chip_type) {
> +	case FT232RL:
> +		eeprom_size = 0x40;
> +		break;
> +	default:
> +		/* Unsupported for brick repair */
> +		return 0;
> +	}
> +
> +	/* Latency timer needs to be 0x77 to unlock EEPROM programming */
> +	if (priv->latency != 0x77) {
> +		orig_latency = priv->latency;
> +		priv->latency = 0x77;
> +		rv = write_latency_timer(port);
> +		priv->latency = orig_latency;
> +		if (rv < 0)
> +			return -EIO;
> +	}

Do you really want to change this without returning to the original?

	Regards
		Oliver