Subject: Re: [PATCH] usb: gadget: Add the console support for usb-to-serial
 port
To: Baolin Wang <baolin.wang@linaro.org>
References: <a69635e749f96fc9f67e93986edb9942ac0ae59f.1447656764.git.baolin.wang@linaro.org>
 <564C9A22.2060102@hurleysoftware.com>
 <CAMz4kuKAn=nEtCkjc6VBVkVbCf7CWYmgzBNHHcg59f=A3y93gg@mail.gmail.com>
Cc: Felipe Balbi <balbi@ti.com>, Greg KH <gregkh@linuxfoundation.org>,
        r.baldyga@samsung.com, fabio.estevam@freescale.com,
        Philip Oberstaller <Philip.Oberstaller@septentrio.com>,
        scottwood@freescale.com, Mark Brown <broonie@kernel.org>,
        USB <linux-usb@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
From: Peter Hurley <peter@hurleysoftware.com>
Message-ID: <564D9828.5060107@hurleysoftware.com>
Date: Thu, 19 Nov 2015 04:36:40 -0500
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On 11/19/2015 01:48 AM, Baolin Wang wrote:
>>
>>> +{
>>> +     struct gscons_info *info = gserial_cons.data;
>>> +     int port_num = gserial_cons.index;
>>> +     struct usb_request *req;
>>> +     struct gs_port *port;
>>> +     struct usb_ep *ep;
>>> +
>>> +     if (port_num >= MAX_U_SERIAL_PORTS || port_num < 0) {
>>> +             pr_err("%s: port num [%d] exceeds the range.\n",
>>> +                    __func__, port_num);
>>> +             return -ENXIO;
>>> +     }
>>> +
>>> +     port = ports[port_num].port;
>>> +     if (!port) {
>>> +             pr_err("%s: serial line [%d] not allocated.\n",
>>> +                    __func__, port_num);
>>> +             return -ENODEV;
>>> +     }
>>> +
>>> +     if (!port->port_usb) {
>>> +             pr_err("%s: no port usb.\n", __func__);
>>> +             return -ENODEV;
>>> +     }
>>> +
>>> +     ep = port->port_usb->in;
>>> +     if (!ep) {
>>> +             pr_err("%s: no usb endpoint.\n", __func__);
>>> +             return -ENXIO;
>>> +     }
>>
>> Looking at the caller, gserial_connect(), none of the error
>> conditions above look possible.
>>
> 
> I re-look the code and do some tests, I found the checking is
> necessary. Cause we get the port number from the console->index, if
> the cmdline is not set the ttyGS0 as the console, the console->index
> will be -1 that is a wrong value. Also the serial.c file will create 1
> usb-to-seial port as default (default n_ports = 1), so we need to
> check the port and the endpoint of the port. So I think here checking
> is necessary and I have tested it.

static void gs_console_connect(int port_num)
{
	.
	.
	if (port_num != gserial_cons.index)
		return;
	.
	.


@@ -1219,6 +1453,7 @@ int gserial_connect(struct gserial *gser, u8 port_num)
 			gser->disconnect(gser);
 	}
 
+	status = gs_console_connect(port_num);
 	spin_unlock_irqrestore(&port->port_lock, flags);
 
 	return status;


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