gspca_pac7302: sporatdic problem when plugging the device

gspca_pac7302: sporatdic problem when plugging the device

[Németh Márton]

Hi,

I have sporadic problem with Labtec Webcam 2200 (0x093a:0x2626). I'm using
gspca_pac7302 driver from http://linuxtv.org/hg/~jfrancois/gspca/
rev 13915 on top of Linux kernel 2.6.32.

I executed the following command in an xterm window:
$ while true; do ./svv; done

Then I plugged and unplugged the device 16 times. When I last plugged the
device I get the following error in the dmesg:

[32393.421313] gspca: probing 093a:2626
[32393.426193] gspca: video0 created
[32393.426958] gspca: probing 093a:2626
[32393.426968] gspca: Interface class 1 not handled here
[32394.005917] pac7302: reg_w_page(): Failed to write register to index 0x49, value 0x0, error -71
[32394.067799] gspca: set alt 8 err -71
[32394.090792] gspca: set alt 8 err -71
[32394.118159] gspca: set alt 8 err -71

The 17th plug was working correctly again. I executed this test on an EeePC 901.

This driver version contains the msleep(4) in the reg_w_buf(). However, here
the reg_w_page() fails, which does not have msleep() inside. I don't know what
is the real problem, but I am afraid that slowing down reg_w_page() would make
the time longer when the device can be used starting from the event when it is
plugged.

Regards,

	Márton Németh

Re: gspca_pac7302: sporatdic problem when plugging the device

[Jean-Francois Moine]

On Sun, 10 Jan 2010 17:58:58 +0100
Németh Márton <nm127@freemail.hu> wrote:

> Then I plugged and unplugged the device 16 times. When I last plugged
> the device I get the following error in the dmesg:
> 
> [32393.421313] gspca: probing 093a:2626
> [32393.426193] gspca: video0 created
> [32393.426958] gspca: probing 093a:2626
> [32393.426968] gspca: Interface class 1 not handled here
> [32394.005917] pac7302: reg_w_page(): Failed to write register to
> index 0x49, value 0x0, error -71
> [32394.067799] gspca: set alt 8 err -71
> [32394.090792] gspca: set alt 8 err -71
> [32394.118159] gspca: set alt 8 err -71
> 
> The 17th plug was working correctly again. I executed this test on an
> EeePC 901.
> 
> This driver version contains the msleep(4) in the reg_w_buf().
> However, here the reg_w_page() fails, which does not have msleep()
> inside. I don't know what is the real problem, but I am afraid that
> slowing down reg_w_page() would make the time longer when the device
> can be used starting from the event when it is plugged.

Hi again,

I don't understand what you mean by:
> This driver version contains the msleep(4) in the reg_w_buf().
> However, here the reg_w_page() fails, which does not have msleep()
> inside.

Indeed the delay will slow down the webcam start (256 * 4 ms = 1s).

If having a delay fixes the problem, then, as the error always occurs
at the same index 0x49 (3 reports), a single delay could be set before
writing to this index. Do you want I code this for test?

Regards.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

Re: gspca_pac7302: sporatdic problem when plugging the device

[Németh Márton]

Jean-Francois Moine wrote:
> On Sun, 10 Jan 2010 17:58:58 +0100
> Németh Márton <nm127@freemail.hu> wrote:
> 
>> Then I plugged and unplugged the device 16 times. When I last plugged
>> the device I get the following error in the dmesg:
>>
>> [32393.421313] gspca: probing 093a:2626
>> [32393.426193] gspca: video0 created
>> [32393.426958] gspca: probing 093a:2626
>> [32393.426968] gspca: Interface class 1 not handled here
>> [32394.005917] pac7302: reg_w_page(): Failed to write register to
>> index 0x49, value 0x0, error -71
>> [32394.067799] gspca: set alt 8 err -71
>> [32394.090792] gspca: set alt 8 err -71
>> [32394.118159] gspca: set alt 8 err -71
>>
>> The 17th plug was working correctly again. I executed this test on an
>> EeePC 901.
>>
>> This driver version contains the msleep(4) in the reg_w_buf().
>> However, here the reg_w_page() fails, which does not have msleep()
>> inside. I don't know what is the real problem, but I am afraid that
>> slowing down reg_w_page() would make the time longer when the device
>> can be used starting from the event when it is plugged.
> 
> Hi again,
> 
> I don't understand what you mean by:
>> This driver version contains the msleep(4) in the reg_w_buf().
>> However, here the reg_w_page() fails, which does not have msleep()
>> inside.
I tought that the msleep(4) call introduced recently fixed the plug-in
problem. It seems I misunderstood something.

> Indeed the delay will slow down the webcam start (256 * 4 ms = 1s).
> 
> If having a delay fixes the problem, then, as the error always occurs
> at the same index 0x49 (3 reports), a single delay could be set before
> writing to this index. Do you want I code this for test?

I tested the behaviour a little bit more. Out of 100 plug-ins:

OK: 81 times
"pac7302: reg_w_page(): Failed to write register to index 0x49, value 0x0, error -71": 19 times

Other error message I haven't got, so 19% of the time writing to register
index 0x49 fails in reg_w_page(). So let's try doing fixing the way you
described. If you send me a patch I can test it.

Regards,

	Márton Németh

Re: gspca_pac7302: sporatdic problem when plugging the device

[Jean-Francois Moine]

On Sun, 10 Jan 2010 21:28:29 +0100
Németh Márton <nm127@freemail.hu> wrote:

> I tested the behaviour a little bit more. Out of 100 plug-ins:
> 
> OK: 81 times
> "pac7302: reg_w_page(): Failed to write register to index 0x49, value
> 0x0, error -71": 19 times
> 
> Other error message I haven't got, so 19% of the time writing to
> register index 0x49 fails in reg_w_page(). So let's try doing fixing
> the way you described. If you send me a patch I can test it.

In some usbsnoop files I have, the index 0x48 is not loaded. May you
try the attached patch (skip the index 0x48 and remove the delay).

(Stéphane, est-ce que tu peux voir aussi ce que ça donne chez toi?)

Regards.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

Re: gspca_pac7302: sporatdic problem when plugging the device

[Jean-Francois Moine]

[-- Attachment #1: Type: text/plain, Size: 365 bytes --]

Sorry, I forgot to attach the patch.

> In some usbsnoop files I have, the index 0x48 is not loaded. May you
> try the attached patch (skip the index 0x48 and remove the delay).
> 
> (Stéphane, est-ce que tu peux voir aussi ce que ça donne chez toi?)

Regards.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

[-- Attachment #2: pac7302.pat --]
[-- Type: application/octet-stream, Size: 826 bytes --]

diff -r 8c11be4edf33 linux/drivers/media/video/gspca/pac7302.c
--- a/linux/drivers/media/video/gspca/pac7302.c	Sun Jan 10 20:36:53 2010 +0100
+++ b/linux/drivers/media/video/gspca/pac7302.c	Mon Jan 11 09:01:24 2010 +0100
@@ -388,7 +388,7 @@
 	0xa4, 0xb8, 0xe0, 0x2a, 0xf6, 0x00, 0x00, 0x00,
 	0x00, 0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 	0x00, 0xfc, 0x00, 0xf2, 0x1f, 0x04, 0x00, 0x00,
-	0x00, 0x00, 0x00, 0xc0, 0xc0, 0x10, 0x00, 0x00,
+	SKIP, 0x00, 0x00, 0xc0, 0xc0, 0x10, 0x00, 0x00,
 	0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 	0x00, 0x40, 0xff, 0x03, 0x19, 0x00, 0x00, 0x00,
 	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
@@ -419,7 +419,6 @@
 		PDEBUG(D_ERR, "reg_w_buf(): "
 		"Failed to write registers to index 0x%x, error %i",
 		index, ret);
-	msleep(4);		/* don't go too quickly */
 	return ret;
 }
 

Re: gspca_pac7302: sporatdic problem when plugging the device

[Németh Márton]

Jean-Francois Moine írta:
> Sorry, I forgot to attach the patch.
> 
>> In some usbsnoop files I have, the index 0x48 is not loaded. May you
>> try the attached patch (skip the index 0x48 and remove the delay).

100 plug-ins out of 100 OK, no errors: I say go for this patch.

I applied the patch on top of rev 14000:bc5737e0e757 from
http://linuxtv.org/hg/~jfrancois/gspca/ . I tested the driver on
top of 2.6.32 with Labtec Webcam 2200 (0x093a:0x2626).

Tested-by: Márton Németh <nm127@freemail.hu>

Thanks for the fix.

Regards,

	Márton Németh