Re: [PATCH] Revert "ARM: cns3xxx: pci: avoid potential stack overflow"

Bjorn Helgaas
2016-05-31T22:02:29Z

[+cc Russell, linux-arm-kernel]

On Tue, May 31, 2016 at 04:58:02PM -0500, Bjorn Helgaas wrote:
> This reverts commit 498a92d42596a7a32c042319eb62a4c3d8081cf1.
>
> Krzysztof reported that this change broke Cavium CNS3xxx, ARMv6 (Laguna
> GW-2388) because the MRRS setting is never written to the hardware.

Krzysztof, can you test this and see whether it fixes the problem for
you?

> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> CC: Arnd Bergmann <arnd@arndb.de>
> CC: Krzysztof Hałasa <khalasa@piap.pl>
> ---
> arch/arm/mach-cns3xxx/pcie.c | 71 ++++++++++++++++++++++++------------------
> 1 file changed, 41 insertions(+), 30 deletions(-)
>
> diff --git a/arch/arm/mach-cns3xxx/pcie.c b/arch/arm/mach-cns3xxx/pcie.c
> index 318394e..c622c30 100644
> --- a/arch/arm/mach-cns3xxx/pcie.c
> +++ b/arch/arm/mach-cns3xxx/pcie.c
> @@ -65,9 +65,8 @@ static void __iomem *cns3xxx_pci_map_bus(struct pci_bus *bus,
>
> /*
> * The CNS PCI bridge doesn't fit into the PCI hierarchy, though
> - * we still want to access it.
> - * We place the host bridge on bus 0, and the directly connected
> - * device on bus 1, slot 0.
> + * we still want to access it. For this to work, we must place
> + * the first device on the same bus as the CNS PCI bridge.
> */
> if (busno == 0) { /* internal PCIe bus, host bridge device */
> if (devfn == 0) /* device# and function# are ignored by hw */
> @@ -212,46 +211,58 @@ static void __init cns3xxx_pcie_check_link(struct cns3xxx_pcie *cnspci)
> }
> }
>
> -static void cns3xxx_write_config(struct cns3xxx_pcie *cnspci,
> - int where, int size, u32 val)
> -{
> - void __iomem *base = cnspci->host_regs + (where & 0xffc);
> - u32 v;
> - u32 mask = (0x1ull << (size * 8)) - 1;
> - int shift = (where % 4) * 8;
> -
> - v = readl_relaxed(base);
> -
> - v &= ~(mask << shift);
> - v |= (val & mask) << shift;
> -
> - writel_relaxed(v, base);
> - readl_relaxed(base);
> -}
> -
> static void __init cns3xxx_pcie_hw_init(struct cns3xxx_pcie *cnspci)
> {
> + int port = cnspci->port;
> + struct pci_sys_data sd = {
> + .private_data = cnspci,
> + };
> + struct pci_bus bus = {
> + .number = 0,
> + .ops = &cns3xxx_pcie_ops,
> + .sysdata = &sd,
> + };
> u16 mem_base = cnspci->res_mem.start >> 16;
> u16 mem_limit = cnspci->res_mem.end >> 16;
> u16 io_base = cnspci->res_io.start >> 16;
> u16 io_limit = cnspci->res_io.end >> 16;
> + u32 devfn = 0;
> + u8 tmp8;
> + u16 pos;
> + u16 dc;
> +
> + pci_bus_write_config_byte(&bus, devfn, PCI_PRIMARY_BUS, 0);
> + pci_bus_write_config_byte(&bus, devfn, PCI_SECONDARY_BUS, 1);
> + pci_bus_write_config_byte(&bus, devfn, PCI_SUBORDINATE_BUS, 1);
>
> - cns3xxx_write_config(cnspci, PCI_PRIMARY_BUS, 1, 0);
> - cns3xxx_write_config(cnspci, PCI_SECONDARY_BUS, 1, 1);
> - cns3xxx_write_config(cnspci, PCI_SUBORDINATE_BUS, 1, 1);
> - cns3xxx_write_config(cnspci, PCI_MEMORY_BASE, 2, mem_base);
> - cns3xxx_write_config(cnspci, PCI_MEMORY_LIMIT, 2, mem_limit);
> - cns3xxx_write_config(cnspci, PCI_IO_BASE_UPPER16, 2, io_base);
> - cns3xxx_write_config(cnspci, PCI_IO_LIMIT_UPPER16, 2, io_limit);
> + pci_bus_read_config_byte(&bus, devfn, PCI_PRIMARY_BUS, &tmp8);
> + pci_bus_read_config_byte(&bus, devfn, PCI_SECONDARY_BUS, &tmp8);
> + pci_bus_read_config_byte(&bus, devfn, PCI_SUBORDINATE_BUS, &tmp8);
> +
> + pci_bus_write_config_word(&bus, devfn, PCI_MEMORY_BASE, mem_base);
> + pci_bus_write_config_word(&bus, devfn, PCI_MEMORY_LIMIT, mem_limit);
> + pci_bus_write_config_word(&bus, devfn, PCI_IO_BASE_UPPER16, io_base);
> + pci_bus_write_config_word(&bus, devfn, PCI_IO_LIMIT_UPPER16, io_limit);
>
> if (!cnspci->linked)
> return;
>
> /* Set Device Max_Read_Request_Size to 128 byte */
> - pcie_bus_config = PCIE_BUS_PEER2PEER;
> -
> + bus.number = 1; /* directly connected PCIe device */
> + devfn = PCI_DEVFN(0, 0);
> + pos = pci_bus_find_capability(&bus, devfn, PCI_CAP_ID_EXP);
> + pci_bus_read_config_word(&bus, devfn, pos + PCI_EXP_DEVCTL, &dc);
> + if (dc & PCI_EXP_DEVCTL_READRQ) {
> + dc &= ~PCI_EXP_DEVCTL_READRQ;
> + pci_bus_write_config_word(&bus, devfn, pos + PCI_EXP_DEVCTL, dc);
> + pci_bus_read_config_word(&bus, devfn, pos + PCI_EXP_DEVCTL, &dc);
> + if (dc & PCI_EXP_DEVCTL_READRQ)
> + pr_warn("PCIe: Unable to set device Max_Read_Request_Size\n");
> + else
> + pr_info("PCIe: Max_Read_Request_Size set to 128 bytes\n");
> + }
> /* Disable PCIe0 Interrupt Mask INTA to INTD */
> - __raw_writel(~0x3FFF, MISC_PCIE_INT_MASK(cnspci->port));
> + __raw_writel(~0x3FFF, MISC_PCIE_INT_MASK(port));
> }
>
> static int cns3xxx_pcie_abort_handler(unsigned long addr, unsigned int fsr,
>
> --
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