Frank,
On Wed, Nov 04 2020 at 17:49, Frank Wunderlich wrote:
>> Von: "Thomas Gleixner" <tglx@xxxxxxxxxxxxx>
>> Any architecture which selects PCI_MSI_ARCH_FALLBACKS and does not have
>> irqdomain support runs into:
>>
>> if (!d)
>> bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
>>
>> which in turn makes pci_msi_supported() return 0 and consequently makes
>> pci_enable_msi[x]() fail.
>
> i'm not that deep into this, but just my thoughts...you are the experts :)
>
> checking for PCI_MSI_ARCH_FALLBACKS here does not help?
>
> something like this:
>
> #ifndef PCI_MSI_ARCH_FALLBACKS
> if (!d)
> bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
> #endif
TBH, that's butt ugly. So after staring long enough into the PCI code I
came up with a way to transport that information to the probe code.
That allows a particular device to say 'I can't do MSI' and at the same
time keeps the warning machinery intact which tells us that a particular
host controller driver is broken.
Uncompiled and untested as usual :)
Thanks,
tglx
---
drivers/pci/controller/pcie-mediatek.c | 4 ++++
drivers/pci/probe.c | 3 +++
include/linux/pci.h | 1 +
3 files changed, 8 insertions(+)
--- a/drivers/pci/controller/pcie-mediatek.c
+++ b/drivers/pci/controller/pcie-mediatek.c
@@ -143,6 +143,7 @@ struct mtk_pcie_port;
* struct mtk_pcie_soc - differentiate between host generations
* @need_fix_class_id: whether this host's class ID needed to be fixed or not
* @need_fix_device_id: whether this host's device ID needed to be fixed or not
+ * @no_msi: Bridge has no MSI support
* @device_id: device ID which this host need to be fixed
* @ops: pointer to configuration access functions
* @startup: pointer to controller setting functions
@@ -151,6 +152,7 @@ struct mtk_pcie_port;
struct mtk_pcie_soc {
bool need_fix_class_id;
bool need_fix_device_id;
+ bool no_msi;
unsigned int device_id;
struct pci_ops *ops;
int (*startup)(struct mtk_pcie_port *port);
@@ -1084,6 +1086,7 @@ static int mtk_pcie_probe(struct platfor
host->ops = pcie->soc->ops;
host->sysdata = pcie;
+ host->no_msi = pcie->soc->no_msi;
err = pci_host_probe(host);
if (err)
@@ -1173,6 +1176,7 @@ static const struct dev_pm_ops mtk_pcie_
};
static const struct mtk_pcie_soc mtk_pcie_soc_v1 = {
+ .no_msi = true,
.ops = &mtk_pcie_ops,
.startup = mtk_pcie_startup_port,
};
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -889,6 +889,9 @@ static int pci_register_host_bridge(stru
if (!bus)
return -ENOMEM;
+ if (bridge->no_msi)
+ bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
+
bridge->bus = bus;
/* Temporarily move resources off the list */
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -545,6 +545,7 @@ struct pci_host_bridge {
unsigned int native_dpc:1; /* OS may use PCIe DPC */
unsigned int preserve_config:1; /* Preserve FW resource setup */
unsigned int size_windows:1; /* Enable root bus sizing */
+ unsigned int no_msi:1; /* Bridge has no MSI support */
/* Resource alignment requirements */
resource_size_t (*align_resource)(struct pci_dev *dev,
