linux-kernel - Re: gspca webcam: need to plug it 5 times before it works

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Message-ID: <1e034f42-6997-d778-dce2-e5d641d91d0e@xs4all.nl>
Date:   Mon, 11 May 2020 12:08:19 +0200
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Pavel Machek <pavel@....cz>,
        kernel list <linux-kernel@...r.kernel.org>,
        linux-media@...r.kernel.org, samr7@...washington.edu,
        gerard@...ll.hobby.nl
Cc:     linux@...nbow-software.org, kilgota@...urn.edu, moinejf@...e.fr
Subject: Re: gspca webcam: need to plug it 5 times before it works

Hi Pavel,

I tested with my sq930x (Creative WebCam Notebook Ultra) and I couldn't
reproduce this. Changing gain/exposure while streaming worked fine too.

It could be flaky usb hardware on your side, it's hard to tell.

Regards,

	Hans

On 04/04/2020 21:18, Pavel Machek wrote:
> Hi!
> 
>>> ..but if I'm patient enough, it eventually starts working... somehow.
>>>
>>> Incoming data seems to go in reliably. Outgoing commands (such as
>>> change gain) don't seem to be unreliable.
>>>
>>> Any idea how to debug / what could be wrong?
>>
>> And I can force it to probe like this: which... makes it work, but
>> does not fix the outgoing commands.
>>
>> Any ideas?
> 
> (Adding people from module_authors to the list.)
> 
>  								Pavel
>  
>> diff --git a/drivers/media/usb/gspca/sq930x.c b/drivers/media/usb/gspca/sq930x.c
>> index c3610247a90e..c9756c0a78df 100644
>> --- a/drivers/media/usb/gspca/sq930x.c
>> +++ b/drivers/media/usb/gspca/sq930x.c
>> @@ -7,6 +7,7 @@
>>   * Copyright (C) 2007 Sam Revitch <samr7@...washington.edu>
>>   */
>>  
>> +#define DEBUG
>>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>>  
>>  #define MODULE_NAME "sq930x"
>> @@ -446,7 +447,7 @@ static void reg_w(struct gspca_dev *gspca_dev, u16 value, u16 index)
>>  			USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
>>  			value, index, NULL, 0,
>>  			500);
>> -	msleep(30);
>> +	msleep(90);
>>  	if (ret < 0) {
>>  		pr_err("reg_w %04x %04x failed %d\n", value, index, ret);
>>  		gspca_dev->usb_err = ret;
>> @@ -635,19 +636,25 @@ static void cmos_probe(struct gspca_dev *gspca_dev)
>>  		SENSOR_MT9V111,
>>  	};
>>  
>> +	printk("CMOS Probing...\n");
>>  	for (i = 0; i < ARRAY_SIZE(probe_order); i++) {
>> +	  printk("Probing type %d...\n", i);
>> +	  
>>  		sensor = &sensor_tb[probe_order[i]];
>>  		ucbus_write(&sd->gspca_dev, sensor->cmd, sensor->cmd_len, 8);
>>  		gpio_init(sd, sensor->gpio);
>> -		msleep(100);
>> +		msleep(200);
>>  		reg_r(gspca_dev, (sensor->i2c_addr << 8) | 0x001c, 1);
>> -		msleep(100);
>> -		if (gspca_dev->usb_buf[0] != 0)
>> +		msleep(200);
>> +		if (gspca_dev->usb_buf[0] != 0) {
>> +		  printk("#### LUCKY! Have type %d\n", i);
>>  			break;
>> +		}
>>  	}
>>  	if (i >= ARRAY_SIZE(probe_order)) {
>> -		pr_err("Unknown sensor\n");
>> -		gspca_dev->usb_err = -EINVAL;
>> +		printk("Unknown sensor ... hmm?\n");
>> +		sd->sensor = probe_order[i-1];
>> +		//gspca_dev->usb_err = -EINVAL;
>>  		return;
>>  	}
>>  	sd->sensor = probe_order[i];
>>
>>
>> -- 
>> (english) http://www.livejournal.com/~pavelmachek
>> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
> 
> 
>