Re: Weird PCI problem

Linux Lists (lists@cyclades.com)
Fri, 16 Apr 1999 14:49:10 -0700 (PDT)

On Thu, 15 Apr 1999, Gerard Roudier wrote:
>
> Could it be possible that bit 0 is just writable for this base address
> register. You can verify that by hacking appropriately the Cyclades driver
> in its detection routine. You may try for example:
>
> - Read the value of the offending base address reg. and save it.
> - Write 1 to that base address reg., then read it and print the value.
> - Write 0 to that base address, then read it and print the value.
> - Restore the value of that base address.

Ok, did that in a machine where the Cyclom-Y board is assigned the proper
address (i.e., the address type it has requested):

- Before:

pcibios_read_config_dword(cyy_bus, cyy_dev_fn,
PCI_BASE_ADDRESS_2,
(unsigned int *) &cy_pci_addr2);

- After:

pcibios_read_config_dword(cyy_bus, cyy_dev_fn,
PCI_BASE_ADDRESS_2,
(unsigned int *) &cy_pci_addr2);
printk("got 0x%lx ; ", cy_pci_addr2);
cy_pci_addr_tmp = cy_pci_addr2;
cy_pci_addr2 |= 0x01;
pcibios_write_config_dword(cyy_bus, cyy_dev_fn,
PCI_BASE_ADDRESS_2,
cy_pci_addr2);
printk("wrote 0x%lx ; ", cy_pci_addr2);
pcibios_read_config_dword(cyy_bus, cyy_dev_fn,
PCI_BASE_ADDRESS_2,
(unsigned int *) &cy_pci_addr2);
printk("got 0x%lx\n", cy_pci_addr2);
cy_pci_addr2 = 0xffffffff;
pcibios_write_config_dword(cyy_bus, cyy_dev_fn,
PCI_BASE_ADDRESS_2,
cy_pci_addr2);
printk("wrote 0x%lx ; ", cy_pci_addr2);
pcibios_read_config_dword(cyy_bus, cyy_dev_fn,
PCI_BASE_ADDRESS_2,
(unsigned int *) &cy_pci_addr2);
printk("got 0x%lx\n", cy_pci_addr2);
pcibios_write_config_dword(cyy_bus, cyy_dev_fn,
PCI_BASE_ADDRESS_2,
cy_pci_addr_tmp);

pcibios_read_config_dword(cyy_bus, cyy_dev_fn,
PCI_BASE_ADDRESS_2,
(unsigned int *) &cy_pci_addr2);

Results:

Cyclades driver 2.1.2.1 1999/04/08 16:17:18
built Apr 16 1999 14:52:03
got 0xe0310000 ; wrote 0xe0310001 ; got 0xe0310000
wrote 0xffffffff ; got 0xffffc000
Cyclom-Y/PCI #1: 0x2e88000-0x2e8bfff, IRQ15, 16 channels starting from
port 0.

That has shown that, at least by using the Linux kernel PCI interface
commands (pcibios_read/write_config), I'm not able to change that bit.
Furthermore, it has shown that I can't write to the last 14 bits [13-0] of
the base address register.

Again, this was done in a machine where the Cyclom-Y board is assigned the
proper address (i.e., the address type it has requested). Do you think
that this test would yell a different result if run on the "deffective"
system ??

Regards,
Ivan

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