propagating failures down to pci_module_init()

DISCUSSION Dave Jones 3 participants 4 messages Jan 20, 2003

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Dave Jones

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2003-01-20 15:48 UTC #0 lore raw

I've got a wierd situation with a certain chipset for agpgart. There are a few cases where I want to be able to use the existing pci_driver api to detect the right PCI device, and call the relevant .probe routine. No problem there.

The problem is that in these cases, I want to be able to read a certain register in that device, and if a bit is 0, bail out of the .probe function with -ENODEV, and make the loading of the module fail.

The problem is that the ENODEV in my .probe routine doesn't propagate back down as far as pci_module_init().

Ideas ?

Dave

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| Dave Jones.        http://www.codemonkey.org.uk
| SuSE Labs

Christoph Hellwig

2003-01-20 16:24 UTC #1 lore raw

Quoted 10 lines · Dave Jones

I've got a wierd situation with a certain chipset for agpgart. There are a few cases where I want to be able to use the existing pci_driver api to detect the right PCI device, and call the relevant .probe routine. No problem there.
The problem is that in these cases, I want to be able to read a certain register in that device, and if a bit is 0, bail out of the .probe function with -ENODEV, and make the loading of the module fail.

Quoted 4 lines

The problem is that the ENODEV in my .probe routine doesn't propagate back down as far as pci_module_init().
Ideas ?

Just use pci_register_driver.

Jeff Garzik

2003-01-20 16:43 UTC #2 lore raw

Quoted 11 lines · Christoph Hellwig

Quoted 10 lines · Dave Jones
I've got a wierd situation with a certain chipset for agpgart. There are a few cases where I want to be able to use the existing pci_driver api to detect the right PCI device, and call the relevant .probe routine. No problem there.
The problem is that in these cases, I want to be able to read a certain register in that device, and if a bit is 0, bail out of the .probe function with -ENODEV, and make the loading of the module fail.

Quoted 6 lines

Quoted 4 lines
The problem is that the ENODEV in my .probe routine doesn't propagate back down as far as pci_module_init().
Ideas ?
Just use pci_register_driver.

Nope. Look at pci_module_init code. It propagates pci_register_driver return value.

The _real_ problem is that ->probe return value is not propagated back to pci_register_driver return value. The reason for this is that you may call ->probe many times, and nobody has written the code to collate the error returns.

Since one can only sanely return an error code when there was _one_ device and it failed, you are rather limited in error propagation.

Jeff

Dave Jones

author

2003-01-20 16:51 UTC #3 lore raw

Quoted 11 lines · Jeff Garzik

Nope. Look at pci_module_init code. It propagates pci_register_driver return value.
The _real_ problem is that ->probe return value is not propagated back to pci_register_driver return value. The reason for this is that you may call ->probe many times, and nobody has written the code to collate the error returns.
Since one can only sanely return an error code when there was _one_ device and it failed, you are rather limited in error propagation.

*nod*. I cheated, and used a static global, which seems to get the desired effect I was after.

Dave

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| Dave Jones.        http://www.codemonkey.org.uk
| SuSE Labs