Re: PCI driver

[Rolf Eike Beer <eike-kernel@sf-tec.de>]

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Am Donnerstag, 15. September 2005 00:27 schrieben Sie:
>Jiri Slaby wrote:
>> Manu Abraham napsal(a):
>>> Jiri Slaby wrote:
>>>> Manu Abraham napsal(a):
>>>>> Jiri Slaby wrote:
>>>>>> you do NOT do this at all, because you have pdev already (the param
>>>>>> of the probe function)
>>>>>
>>>>> I rewrote the entire thing like this including the pci_remove
>>>>> function too, but now it so seems that in the remove function,
>>>>> pci_get_drvdata(pdev) returns NULL, and hence i get an Oops at
>>>>> module removal.
>>>
>>> I just found that, pci_enable_device() fails. So what's the way to go
>>> ahead ?
>>
>> JESUS.
>
>Hmm.. i finally got it to work. It seems pci_get_device() is necessary,
>i can't seem to enable the device or request for an IRQ the way you
>suggested. It looks some quirks are there though ..
>
>If only i could explain why it works this way and not the other way ..
>
>Thanks for the help,
>Regards,
>Manu
>
>
>
>[   81.269655] mantis_pci_probe: Got a device
>[   81.269825] mantis_pci_probe: We got an IRQ
>[   81.269987] mantis_pci_probe: We finally enabled the device
>[   81.270191] Mantis Rev 1, irq: 23, latency: 32
>[   81.270289] memory: 0xefeff000, mmio: f9218000
>[   81.270519] Trying to free free IRQ23
>[   90.485885] mantis_pci_remove: Removing -->Mantis irq: 23, latency: 32
>[   90.485887] memory: 0xefeff000, mmio: 0xf9218000
>[   90.486293] Trying to free free IRQ23
>[   90.486429] Trying to free nonexistent resource <efeff000-efefffff>
>
>
>
>
>static int __devinit mantis_pci_probe(struct pci_dev *pdev, const struct
>pci_device_id *mantis_pci_table)
>{
>	u8 revision, latency;
>	u8 data[2];
>	struct mantis_pci *mantis;
>	mantis = (struct mantis_pci *) kmalloc(sizeof (struct mantis_pci),
>GFP_KERNEL);

Cast is unneeded.

>	if (mantis == NULL) {
>		dprintk(verbose, MANTIS_ERROR, 1, "Out of memory");
>		return -ENOMEM;
>	}
>
>	pdev = pci_get_device(PCI_VENDOR_ID_MANTIS, PCI_DEVICE_ID_MANTIS_R11,
>NULL);

Hm, this is wrong. pdev contains the struct pci_dev of the found device. If 
you do it your way the first device is always used (and the found one is 
ignored). When you have two mantis cards in your system it will happily trash 
the reference counting. The driver needs to work if you comment out this 
line.

>	if (pdev) {

This if is not needed either, the probe function is only called if pdev is 
set.

>		dprintk(verbose, MANTIS_ERROR, 1, "Got a device");
>		mantis->mantis_addr = pci_resource_start(pdev, 0);
>		if (!request_mem_region(pci_resource_start(pdev, 0),
>			pci_resource_len(pdev, 0), DRIVER_NAME)) {
>			dprintk(verbose, MANTIS_ERROR, 1, "Request for memory region failed");
>			goto err0;
>		}
>		if ((mantis->mantis_mmio = ioremap(mantis->mantis_addr, 0x1000)) ==
>NULL) {
>			dprintk(verbose, MANTIS_ERROR, 1, "IO remap failed");
>			goto err1;
>		}
>		if (request_irq(pdev->irq, (void *) mantis_pci_irq, SA_SHIRQ |
>						SA_INTERRUPT, DRIVER_NAME, (void *) mantis) < 0) {
>			dprintk(verbose, MANTIS_ERROR, 1, "Mantis IRQ registration failed");
>			goto err2;
>		}
>		dprintk(verbose, MANTIS_DEBUG, 1, "We got an IRQ");
>		if (pci_enable_device(pdev)) {
>			dprintk(verbose, MANTIS_ERROR, 1, "Mantis PCI device enable failed");
>			goto err3;
>		}

IIRC the call to pci_enable_device() must be the first thing you do. This will 
do the things like assigning memory regions to the device and so on.

>		dprintk(verbose, MANTIS_DEBUG, 1, "We finally enabled the device");
>		pci_set_master(pdev);
>		pci_read_config_byte(pdev, PCI_LATENCY_TIMER, &latency);
>		pci_read_config_byte(pdev, PCI_CLASS_REVISION, &revision);
>		mantis->latency = latency;
>		mantis->revision = revision;
>		if (!latency) {
>			pci_write_config_byte(pdev, PCI_LATENCY_TIMER, 32);
>		}
>		pci_set_drvdata(pdev, mantis);
>		dprintk(verbose, MANTIS_ERROR, 0, "Mantis Rev %d, ", mantis->revision);
>		dprintk(verbose, MANTIS_ERROR, 0, "irq: %d, latency: %d\nmemory:
>0x%04x, mmio: %p\n", pdev->irq, mantis->latency,
>			mantis->mantis_addr, mantis->mantis_mmio);
>
>		pci_dev_put(pdev);
>
>	} else {
>		dprintk(verbose, MANTIS_ERROR, 1, "No device found");
>		return -ENODEV;
>	}

return 0;

>err3:
>	free_irq(pdev->irq, pdev);
>err2:
>	if (mantis->mantis_mmio)
>		iounmap(mantis->mantis_mmio);
>err1:
>	release_mem_region(pci_resource_start(pdev, 0),
>				pci_resource_len(pdev, 0));
>err0:
>	kfree(mantis);
>
>	return 0;
>}

Returning 0 in error cases is just wrong. And you free the assignments even in 
case of success AFAICS. Try the return I introduced above and see what 
happens.

Eike

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