Arnd Bergmann <a...@arndb.de> writes:
> The cns3xxx_pcie_hw_init function uses excessive kernel
> stack space because of a hack that puts a fake struct
> pci_sys_data and struct pci_bus on the stack in order to
> call the generic pci_bus_read_config accessors, which causes
> a warning in ARM allmodconfig builds:
>
> arch/arm/mach-cns3xxx/pcie.c:266:1: warning: the frame size of 1080 bytes is
> larger than 1024 bytes
>
> This rewrites the code in question to use a private
> implementation of the config space access for the same
> purpose, getting rid of the local variables and the
> warning in the process. As part of this, we have to
> use an open-coded version of pci_bus_find_capability(),
> which unfortunately complicates the implementation.
Wouldn't it be better to simply use static structs for this purpose?
The hack isn't pretty, though.
> + regs = cnspci->cfg0_regs + (PCI_DEVFN(1, 0) << 12);
> +
Some comment about would be helpful. Such as this:
> - bus.number = 1; /* directly connected PCIe device */
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> + pos = cns3xxx_pci_raw_read_config(regs, PCI_CAPABILITY_LIST, 1);
> + while (cns3xxx_pci_raw_read_config(regs, pos, 1) != PCI_CAP_ID_EXP)
> + pos = cns3xxx_pci_raw_read_config(regs, pos +
> PCI_CAP_LIST_NEXT, 1);
> +
I wonder if this can fail (i.e., no PCI_CAP_ID_EXP capability).
> + dc = cns3xxx_pci_raw_read_config(regs, pos + PCI_EXP_DEVCTL, 2);
> + dc &= ~(0x3 << 12); /* Clear Device Control Register [14:12] */
> + cns3xxx_pci_raw_write_config(regs, pos + PCI_EXP_DEVCTL, 2, dc);
> + dc = cns3xxx_pci_raw_read_config(regs, pos + PCI_EXP_DEVCTL, 2);
> + if (!(dc & (0x3 << 12)))
> + pr_info("PCIe: Set Device Max_Read_Request_Size to 128 byte\n");
> +
This seems to revert 367dc4b75f4349d5363bc3ebdc030939db944786. Why do
you want to do it?
--
Krzysztof Halasa
Research Institute for Automation and Measurements PIAP
Al. Jerozolimskie 202, 02-486 Warsaw, Poland
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