I am having a problem getting the i2c-pcf-epp module working.
As a quick first question:
How can I confirm that my parallel port is in EPP mode?
Where I am up to.
I have patched and complied the kernel (I'm using 2.4.20) but need some help.
A few facts about me so you may know how to respond.
1) I am not a computer programmer
2) I cannot program in C to save my life
3) I have built a parallel port to i2c adaptor circuit using a PCF8584 which I
have plugged into my notebook parallel port.
4) It isn't working and I am trying to find out why.
5) Any help would be greatly appreciated.
6) My biggest problem is I think I am getting a kernel oops every time
modprobe i2c-pcf-epp fails
I have attached part of my log with debuging on a the very bottom of this
post. Please ignore all the extra rubbish in there, that's just me trying to
figure out what is going on.
This is what I think the problem is (the kernel oops at any rate)
In i2c-pcf-epp.c there is a function:
int __init i2c_pcfepp_init(void)
under which is the block of code:
if (pcf_epp_init(pepp) == 0) {
int ret;
if ( (ret = i2c_pcf_add_bus(&pcf_epp_ops)) < 0) {
printk(KERN_WARNING "i2c_pcf_add_bus caused an error: %d\n",ret);
release_region(pepp->pe_base , 5);
return ret;
}
} else {
return -ENODEV;
}
printk(KERN_DEBUG "i2c-pcf-epp.o: found device at %#x.\n", pepp->pe_base);
return 0;
}
I think the problem relates to
release_region(pepp->pe_base , 5);
Under normal circumstances this is not a problem but if the i2c_pcf_add_bus
fails you will get an oops if you have an irq assigned.
I have tried the following modification and it works (meaning I don't get the
oops). Looking at it a bit more though I think that between the if ( (ret =
i2c_pcf_add_bus(&pcf_epp_ops)) < 0) and the return ret should simply be a
call to
cleanup_module()
Could someone look over this and acknowledge and patch if necessary please.
Example code that doesn't give the oops
if (pcf_epp_init(pepp) == 0) {
int ret;
if ( (ret = i2c_pcf_add_bus(&pcf_epp_ops)) < 0) {
printk(KERN_WARNING "i2c_pcf_add_bus caused an error: %d\n",ret);
if ( gpe.pe_irq > 0 ) {
disable_irq(gpe.pe_irq);
free_irq(gpe.pe_irq, &gpe);
}
release_region(pepp->pe_base , 5);
return ret;
}
} else {
return -ENODEV;
}
printk(KERN_DEBUG "i2c-pcf-epp.o: found device at %#x.\n", pepp->pe_base);
return 0;
}
--
Best Regards,
David Price
---------------------
Feb 12 14:42:10 c17008 kernel: i2c-algo-pcf.o: hw routines for PCF8584 EPP
adapter registered.
Feb 12 14:42:10 c17008 kernel: Registering th new adaptor pcf_algo.id=20000
Feb 12 14:42:10 c17008 kernel: Just about to if ((i =
pcf_init_8584(pcf_adap)))
Feb 12 14:42:10 c17008 kernel: i2c-algo-pcf.o: pcf_init_8584
Feb 12 14:42:10 c17008 kernel: i2c-pcf-epp.o: Read control 0xff
Feb 12 14:42:10 c17008 kernel: i2c-algo-pcf.o: PCF state 0xff
Feb 12 14:42:10 c17008 kernel: i2c-pcf-epp.o: Write control 0x88
Feb 12 14:42:10 c17008 kernel: set_pcf(adap, 1, I2C_PCF_PIN=80
Feb 12 14:42:10 c17008 kernel: i2c-pcf-epp.o: Read control 0xff
Feb 12 14:42:10 c17008 kernel: if (((temp = get_pcf(adap, 1)); temp=ff
Feb 12 14:42:10 c17008 kernel: i2c-algo-pcf.o: PCF detection failed -- can't
select S0 (0xff).
Feb 12 14:42:10 c17008 kernel: pcf_init_8584(pcf_adap)=fffffffa
Feb 12 14:42:10 c17008 kernel: i2c-algo-pcf.o: pcf_init_8584
Feb 12 14:42:10 c17008 kernel: i2c-pcf-epp.o: Read control 0xff
Feb 12 14:42:10 c17008 kernel: i2c-algo-pcf.o: PCF state 0xff
Feb 12 14:42:10 c17008 kernel: i2c-pcf-epp.o: Write control 0x88
Feb 12 14:42:10 c17008 kernel: set_pcf(adap, 1, I2C_PCF_PIN=80
Feb 12 14:42:10 c17008 kernel: i2c-pcf-epp.o: Read control 0xff
Feb 12 14:42:10 c17008 kernel: if (((temp = get_pcf(adap, 1)); temp=ff
Feb 12 14:42:10 c17008 kernel: i2c-algo-pcf.o: PCF detection failed -- can't
select S0 (0xff).
Feb 12 14:42:10 c17008 kernel: about to return to i2c-pcf-epp i2c_pcfepp_init
i=fffffffa
Feb 12 14:42:10 c17008 kernel: i2c_pcf_add_bus caused an error: -6
Feb 12 14:42:10 c17008 kernel: Just about to die &pepp->pr_base=e4960544
Feb 12 14:42:10 c17008 kernel: rest of value pepp->pr_base=378
Feb 12 14:42:11 c17008 kernel: Unable to handle kernel paging request at
virtual address e495fe3c
Feb 12 14:42:11 c17008 kernel: printing eip:
Feb 12 14:42:11 c17008 kernel: c023b482
Feb 12 14:42:11 c17008 kernel: *pde = 23fae067
Feb 12 14:42:11 c17008 kernel: *pte = 00000000
Feb 12 14:42:11 c17008 kernel: Oops: 0000
Feb 12 14:42:11 c17008 kernel: CPU: 0
Feb 12 14:42:11 c17008 kernel: EIP: 0010:[<c023b482>] Tainted: P
Feb 12 14:42:11 c17008 kernel: EFLAGS: 00010297
Feb 12 14:42:11 c17008 kernel: eax: e495fe3c ebx: 0000000a ecx: e495fe3c
edx: fffffffe
Feb 12 14:42:11 c17008 kernel: esi: d5eb20de edi: 00000000 ebp: ffffffff
esp: dcf3beac
Feb 12 14:42:11 c17008 kernel: ds: 0018 es: 0018 ss: 0018
Feb 12 14:42:11 c17008 kernel: Process kdeinit (pid: 1321, stackpage=dcf3b000)
Feb 12 14:42:11 c17008 kernel: Stack: dcf3bef0 ffffffff 0000000a 00000000
0000000a 0000000a 00000001 00000000
Feb 12 14:42:11 c17008 kernel: ffffffff ffffffff e1e7c580 d5eb20dc
00000007 c02e09e4 c023b657 d5eb20dc
Feb 12 14:42:11 c17008 kernel: 2a14df24 c0267419 dcf3bf18 c023b67f
d5eb20dc c0267416 dcf3bf14 c010a560
Feb 12 14:42:11 c17008 kernel: Call Trace: [<c023b657>] [<c023b67f>]
[<c010a560>] [<c0161f33>] [<c015f4f1>]
Feb 12 14:42:11 c17008 kernel: [<c013c3e3>] [<c01090ef>]
Feb 12 14:42:11 c17008 kernel:
Feb 12 14:42:11 c17008 kernel: Code: 80 38 00 74 07 40 4a 83 fa ff 75 f4 29 c8
83 e7 10 89 c3 75
