Hi Stefano,
On 09/02/2021 17:47, Stefano Stabellini wrote:
On Tue, 9 Feb 2021, Bertrand Marquis wrote:
Hi Stefano,
On 8 Feb 2021, at 23:56, Stefano Stabellini <sstabell...@kernel.org> wrote:
PCI buses differ from default buses in a few important ways, so it is
important to detect them properly. Normally, PCI buses are expected to
have the following property:
device_type = "pci"
In reality, it is not always the case. To handle PCI bus nodes that
don't have the device_type property, also consider the node name: if the
node name is "pcie" or "pci" then consider the bus as a PCI bus.
This commit is based on the Linux kernel commit
d1ac0002dd29 "of: address: Work around missing device_type property in
pcie nodes".
This fixes Xen boot on RPi4.
I am a bit confused with this sentence... How did you manage to boot Xen
on RPi4 before hand?
We are really handling here a wrong device-tree bug that could easily be fixed
by the user.
We should at least mention in the commit message that this is a workaround
to solve RPi4 buggy device tree.
Not sure if it can be "easily" fixed by the user -- it took me a few
hours to figure out what the problem was, and I know Xen and device tree
pretty well :-)
Yes it would be good to have a link to the discussion in the commit
message, using the Link tag. It could be done on commit, or I can add it
to the next version.
A summary of the discussion would be useful in the commit message so a
reader can easily make the connection between the Linux commit and the
Xen one.
Link: https://lore.kernel.org/xen-devel/ybmqq3tzu++aa...@mattapan.m5p.com/
Signed-off-by: Stefano Stabellini <stefano.stabell...@xilinx.com>
diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index 18825e333e..f1a96a3b90 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -563,14 +563,28 @@ static unsigned int dt_bus_default_get_flags(const __be32
*addr)
* PCI bus specific translator
*/
+static bool_t dt_node_is_pci(const struct dt_device_node *np)
+{
+ bool is_pci = !strcmp(np->name, "pcie") || !strcmp(np->name, "pci");
The Linux commit is a bit more restrictive and only does that for “pcie”.
Any reason why you also want to have this workaround done also for “pci” ?
Yes, that's because in our case the offending node is named "pci" not
"pcie" so the original Linux commit wouldn't cover it.
+
+ if (is_pci)
+ printk(XENLOG_WARNING "%s: Missing device_type\n", np->full_name);
+
+ return is_pci;
+}
+
static bool_t dt_bus_pci_match(const struct dt_device_node *np)
{
/*
* "pciex" is PCI Express "vci" is for the /chaos bridge on 1st-gen PCI
* powermacs "ht" is hypertransport
+ *
+ * If none of the device_type match, and that the node name is
+ * "pcie" or "pci", accept the device as PCI (with a warning).
*/
return !strcmp(np->type, "pci") || !strcmp(np->type, "pciex") ||
- !strcmp(np->type, "vci") || !strcmp(np->type, "ht");
+ !strcmp(np->type, "vci") || !strcmp(np->type, "ht") ||
+ dt_node_is_pci(np);
}
static void dt_bus_pci_count_cells(const struct dt_device_node *np,
--
Julien Grall
