On Mon, Nov 23, 2015 at 01:40:26PM +0100, Thierry Reding wrote:
> From: Thierry Reding <treding@xxxxxxxxxx>
>
> The configuration space mapping on Tegra is somewhat special, and in
It'd be nice to have a tiny hint about specifically what is special
about Tegra config space mapping.
> order to avoid wasting virtual address space the configuration space
> for each bus needs to be stitched together from several blocks which
> form a single continuous virtual address range for accessors.
>
> Currently the configuration space is mapped upon the first access to
> one of its registers. However, the mapping operation may sleep under
> certain circumstances, so doing it from the configuration space
> accessors (they are protected by a spin lock) will trigger a warning.
Can you include the exact warning? Does it happen always? Always on
the first config access to a bus?
> To avoid the warning, use the ->add_bus() callback to perform the
> mapping at enumeration time when the operation is allowed to sleep.
>
> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
> ---
> drivers/pci/host/pci-tegra.c | 40 +++++++++++++++++++---------------------
> 1 file changed, 19 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
> index 3018ae52e092..c3666f9d7ef1 100644
> --- a/drivers/pci/host/pci-tegra.c
> +++ b/drivers/pci/host/pci-tegra.c
> @@ -426,31 +426,23 @@ free:
> return ERR_PTR(err);
> }
>
> -/*
> - * Look up a virtual address mapping for the specified bus number. If no such
> - * mapping exists, try to create one.
> - */
> -static void __iomem *tegra_pcie_bus_map(struct tegra_pcie *pcie,
> - unsigned int busnr)
> +static int tegra_pcie_add_bus(struct pci_bus *bus)
> {
> - struct tegra_pcie_bus *bus;
> + struct tegra_pcie *pcie = sys_to_pcie(bus->sysdata);
> + struct tegra_pcie_bus *b;
>
> - list_for_each_entry(bus, &pcie->buses, list)
> - if (bus->nr == busnr)
> - return (void __iomem *)bus->area->addr;
> + b = tegra_pcie_bus_alloc(pcie, bus->number);
> + if (IS_ERR(b))
> + return PTR_ERR(b);
>
> - bus = tegra_pcie_bus_alloc(pcie, busnr);
> - if (IS_ERR(bus))
> - return NULL;
> + list_add_tail(&b->list, &pcie->buses);
>
> - list_add_tail(&bus->list, &pcie->buses);
> -
> - return (void __iomem *)bus->area->addr;
> + return 0;
> }
>
> -static void __iomem *tegra_pcie_conf_address(struct pci_bus *bus,
> - unsigned int devfn,
> - int where)
> +static void __iomem *tegra_pcie_map_bus(struct pci_bus *bus,
> + unsigned int devfn,
> + int where)
> {
> struct tegra_pcie *pcie = sys_to_pcie(bus->sysdata);
> void __iomem *addr = NULL;
> @@ -466,7 +458,12 @@ static void __iomem *tegra_pcie_conf_address(struct pci_bus *bus,
> }
> }
> } else {
> - addr = tegra_pcie_bus_map(pcie, bus->number);
> + struct tegra_pcie_bus *b;
> +
> + list_for_each_entry(b, &pcie->buses, list)
> + if (b->nr == bus->number)
> + addr = (void __iomem *)b->area->addr;
> +
> if (!addr) {
> dev_err(pcie->dev,
> "failed to map cfg. space for bus %u\n",
> @@ -481,7 +478,8 @@ static void __iomem *tegra_pcie_conf_address(struct pci_bus *bus,
> }
>
> static struct pci_ops tegra_pcie_ops = {
> - .map_bus = tegra_pcie_conf_address,
> + .add_bus = tegra_pcie_add_bus,
> + .map_bus = tegra_pcie_map_bus,
> .read = pci_generic_config_read32,
> .write = pci_generic_config_write32,
> };
> --
> 2.5.0
>
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