On Sat, Sep 12, 2015 at 12:21:57AM +0100, David Daney wrote:
> From: David Daney <david.daney@xxxxxxxxxx>
>
> There are two problems with the bus_max calculation:
>
> 1) The u8 data type can overflow for large config space windows.
>
> 2) The calculation is incorrect for a bus range that doesn't start at
> zero.
>
> Since the configuration space is relative to bus zero, make bus_max
> just be the size of the config window scaled by bus_shift. Then clamp
> it to a maximum of 255, per PCI. Use a data type of int to avoid
> overflow problems.
>
> Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> ---
> drivers/pci/host/pci-host-generic.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
> index cd6f898..fce5bf7 100644
> --- a/drivers/pci/host/pci-host-generic.c
> +++ b/drivers/pci/host/pci-host-generic.c
> @@ -164,7 +164,7 @@ out_release_res:
> static int gen_pci_parse_map_cfg_windows(struct gen_pci *pci)
> {
> int err;
> - u8 bus_max;
> + int bus_max;
> resource_size_t busn;
> struct resource *bus_range;
> struct device *dev = pci->host.dev.parent;
> @@ -177,8 +177,9 @@ static int gen_pci_parse_map_cfg_windows(struct gen_pci *pci)
> }
>
> /* Limit the bus-range to fit within reg */
> - bus_max = pci->cfg.bus_range->start +
> - (resource_size(&pci->cfg.res) >> pci->cfg.ops.bus_shift) - 1;
> + bus_max = (resource_size(&pci->cfg.res) >> pci->cfg.ops.bus_shift) - 1;
> + if (bus_max > 255)
> + bus_max = 255;
> pci->cfg.bus_range->end = min_t(resource_size_t,
> pci->cfg.bus_range->end, bus_max);
Hmm, this is changing the meaning of the bus-range property in the
device-tree, which really needs to match what IEEE Std 1275-1994 requires.
My understanding was that the bus-range could be used to offset the config
space, which is why it's subtracted from the bus number in
gen_pci_map_cfg_bus_[e]cam. Also, why is your config space so large that
we end up overflowing bus_max?
Will
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