[PATCH] drivers: pci: initialise class to 0 before reading

[Bin Meng]

Hi Hugh,

On Wed, Jan 1, 2020 at 9:50 PM Hugh Cole-Baker <sigmaris at gmail.com> wrote:
>
> Hi Bin,
>
> > On 1 Jan 2020, at 13:25, Bin Meng <bmeng.cn at gmail.com> wrote:
> >
> > On Wed, Jan 1, 2020 at 7:15 PM Hugh Cole-Baker <sigmaris at gmail.com> wrote:
> >>
> >> Otherwise, uninitialised memory from the upper 32 bits can end up in
> >> find_id.class, and this causes bugs later when looking for a driver for
> >> the class.
> >>
> >> Signed-off-by: Hugh Cole-Baker <sigmaris at gmail.com>
> >> ---
> >> drivers/pci/pci-uclass.c | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
> >> index fab20fc60e..c28a1cc363 100644
> >> --- a/drivers/pci/pci-uclass.c
> >> +++ b/drivers/pci/pci-uclass.c
> >> @@ -773,7 +773,7 @@ int pci_bind_bus_devices(struct udevice *bus)
> >>             bdf += PCI_BDF(0, 0, 1)) {
> >>                struct pci_child_platdata *pplat;
> >>                struct udevice *dev;
> >> -               ulong class;
> >> +               ulong class = 0;
> >>
> >>                if (!PCI_FUNC(bdf))
> >>                        found_multi = false;
> >> --
> >
> > I see class is initialized in the call to:
> >
> > pci_bus_read_config(bus, bdf, PCI_CLASS_REVISION, &class,
> >    PCI_SIZE_32);
> > class >>= 8;
> >
>
> Maybe the driver I'm working with is doing its read_config wrongly? I'm
> trying to use this Rockchip PCIe driver [1] with upstream u-boot. The
> driver casts &class to u32*, uses readl() and only sets the lower 32
> bits. I was assuming that this was normal for a read of PCI_SIZE_32.
> However, looking at some of the other drivers, it seems like it should
> be using pci_conv_32_to_size() instead?
>

The bug should be that

https://github.com/radxa/u-boot/blob/rk3399-pie-gms-express-baseline/drivers/pci/pcie_rockchip.c#L318

u32 *val should be declared as ulong *val.

> [1] https://github.com/radxa/u-boot/blob/rk3399-pie-gms-express-baseline/drivers/pci/pcie_rockchip.c#L435
>

Regards,
Bin