Hi Bjorn,
On 1/26/2016 10:22 AM, Bjorn Helgaas wrote:
Hi Ray,
On Wed, Jan 20, 2016 at 02:55:10PM -0800, Ray Jui wrote:
Commit 943ebae781f5 ("PCI: iproc: Add PAXC interface support") causes
regression on EP device detection on BCMA based platforms. This patch
fixes the issue by allowing multiple devices to be configured on the
same bus, for all PAXB based child buses
Reported-by: Rafal Milecki <zajec5@xxxxxxxxx>
Fixes: 943ebae781f5 ("PCI: iproc: Add PAXC interface support")
Signed-off-by: Ray Jui <rjui@xxxxxxxxxxxx>
---
drivers/pci/host/pcie-iproc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/host/pcie-iproc.c b/drivers/pci/host/pcie-iproc.c
index 5816bce..4627561 100644
--- a/drivers/pci/host/pcie-iproc.c
+++ b/drivers/pci/host/pcie-iproc.c
@@ -171,10 +171,11 @@ static inline void iproc_pcie_ob_write(struct iproc_pcie *pcie,
}
static inline bool iproc_pcie_device_is_valid(struct iproc_pcie *pcie,
+ unsigned int busnum,
unsigned int slot,
unsigned int fn)
{
- if (slot > 0)
+ if ((pcie->type == IPROC_PCIE_PAXC || busnum == 0) && slot > 0)
return false;
/* PAXC can only support limited number of functions */
I don't understand this. Here's the whole function (with this patch
applied):
static inline bool iproc_pcie_device_is_valid(struct iproc_pcie *pcie,
unsigned int busnum,
unsigned int slot,
unsigned int fn)
{
if ((pcie->type == IPROC_PCIE_PAXC || busnum == 0) && slot > 0)
return false;
/* PAXC can only support limited number of functions */
if (pcie->type == IPROC_PCIE_PAXC && fn >= MAX_NUM_PAXC_PF)
return false;
return true;
}
This says:
- On bus 00, device 0 is the only valid device. That seems
plausible because the devices on bus 00 are probably built-in to
the SoC.
- On PAXC-based systems, device 0 is the only valid device on *any*
bus. Is that really true? If there's any way to add a plug-in
card, this seems overly restrictive.
Yah, PAXC is connected with one internal device within the SoC. There's
no connection brought out of the chip.
PCIe devices are generally all device 0, but this would mean you
cannot plug in a PCIe-to-PCI bridge leading to a PCI device with a
non-zero device number.
I think it also means you could not plug in a PCIe device with ARI
enabled, because I think we store the upper 5 bits of the 8-bit
ARI function number in the PCI_SLOT bits.
- On PAXC-based systems, only functions 0, 1, 2, and 3 are valid
anywhere in the hierarchy. I think this again restricts what what
cards can be plugged in.
Yes, the internal device connected to PAXC supports 4 physical functions.
If iProc only supports devices built directly into the SoC, maybe
these constraints are valid. But if it supports any plugin or
external devices, they don't seem to make sense.
Correct. PAXC only connects to one built-in device, while PAXB can
support external EP devices.
Also, is it the case that an iProc root bus is always bus number zero?
That's certainly not the case for many other host controllers, but
maybe you only have one possible host controller per system and the
base number is not programmable.
An iProc based SoC can potentially have multiple root complexes, with
each of them resides on separate PCIe domain (and always on bus 0). I
think this is similar to how Exynos PCIe host controller is modeled.
Bjorn
Thanks,
Ray
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