During a kdump kernel boot in PowerPC, we request a reset of the
PHBs to the FW. It makes sense, since if we are booting a kdump
kernel it means we had some trouble before and we cannot rely in
the adapters' health; they could be in a bad state, hence the
reset is needed.
But not only in a kdump kernel we could use this reset - there are
situations, specially when debugging drivers, that we could break
an adapter in a way it requires such reset. One can tell to just
go ahead and reboot the machine, but happens that many times doing
kexec is much faster, and so preferable than a full power cycle.
Also, we could have situations in which adapters are in bad state
due to adapter's FW issue, and only a PHB Fundamental Reset could
revive them.
This patch enables the reset_devices parameter to perform such reset.
The parameter is barely used - only few drivers make use of it.
This is a PowerPC-only change.
Signed-off-by: Guilherme G. Piccoli <gpicc...@linux.vnet.ibm.com>
---
This patch was built/tested against powerpc/next branch.
We recently had a situation in which i40e driver couldn't start,
even after a full power cycle, due to a bug in its FW triggered
by a DCB condition in switch (thanks Mauro for narrowing this).
This patch enabled us to revive the adapter and use network
while debugging.
Documentation/admin-guide/kernel-parameters.txt | 3 ++-
arch/powerpc/platforms/powernv/pci-ioda.c | 7 +++++--
init/main.c | 4 ++--
3 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index 05496622b4ef..e75cf4a9345d 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3656,7 +3656,8 @@
the bottom of the address space.
reset_devices [KNL] Force drivers to reset the underlying device
- during initialization.
+ during initialization. In PowerPC bare-metal (aka
+ PowerNV), it also issues a Fundamental Reset on PHBs.
resume= [SWSUSP]
Specify the partition device for software suspend
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c
b/arch/powerpc/platforms/powernv/pci-ioda.c
index fb5cd7511189..0a5f2a221a09 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -4014,9 +4014,12 @@ static void __init pnv_pci_init_ioda_phb(struct
device_node *np,
* If we're running in kdump kernel, the previous kernel never
* shutdown PCI devices correctly. We already got IODA table
* cleaned out. So we have to issue PHB reset to stop all PCI
- * transactions from previous kernel.
+ * transactions from previous kernel. Also, reset_devices
+ * parameter will force the issue of reset (useful in debug
+ * scenarios).
*/
- if (is_kdump_kernel()) {
+
+ if (is_kdump_kernel() || reset_devices) {
pr_info(" Issue PHB reset ...\n");
pnv_eeh_phb_reset(hose, EEH_RESET_FUNDAMENTAL);
pnv_eeh_phb_reset(hose, EEH_RESET_DEACTIVATE);
diff --git a/init/main.c b/init/main.c
index 0ee9c6866ada..9d3dc50fadfe 100644
--- a/init/main.c
+++ b/init/main.c
@@ -157,10 +157,10 @@ EXPORT_SYMBOL(reset_devices);
static int __init set_reset_devices(char *str)
{
reset_devices = 1;
- return 1;
+ return 0;
}
-__setup("reset_devices", set_reset_devices);
+early_param("reset_devices", set_reset_devices);
static const char *argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
const char *envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
--
2.14.2
