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authorAndrew Donnellan <andrew.donnellan@au1.ibm.com>2015-12-08 05:59:25 (GMT)
committerMichael Ellerman <mpe@ellerman.id.au>2015-12-09 03:05:10 (GMT)
commitdc9c41bd9ece090b54eb8f1bbdfb1930e10d3ae7 (patch)
treec846961873ea2b8037fc381a3e8aa9c92dbc0227 /arch
parent5b01310cfc8d2302dcca1d8da42873edab2ef784 (diff)
downloadlinux-dc9c41bd9ece090b54eb8f1bbdfb1930e10d3ae7.tar.xz
Revert "powerpc/eeh: Don't unfreeze PHB PE after reset"
This reverts commit 527d10ef3a315d3cb9dc098dacd61889a6c26439. The reverted commit breaks cxlflash devices following an EEH reset (and possibly other cxl devices, however this has not been tested). The reverted commit changed the behaviour of eeh_reset_device() so that PHB PEs are not unfrozen following the completion of the reset. This should not be problematic, as no device resources should have been associated with the PHB PE. However, when attempting to load the cxlflash driver after a reset, the driver attempts to read Vital Product Data through a call to pci_read_vpd() (which is called on the physical cxl device, not on the virtual AFU device). pci_read_vpd() in turn attempts to read from the cxl device's config space. This fails, as the PE it's trying to read from is still frozen. In turn, the driver gets an -ENODEV and fails to initialise. It appears this issue only affects some parts of the VPD area, as "lspci -vvv", which only reads a subset of the VPD bytes, is not broken by the original patch. At this stage, we don't fully understand why we're trying to read a frozen PE, and we don't know how this affects other cxl devices. It is possible that there is an underlying bug in the cxl driver or the powerpc CAPI support code, or alternatively a bug in the PCI resource allocation/mapping code that is incorrectly mapping resources to PE#0. As such, this fix is incomplete, however it is necessary to prevent a serious regression in CAPI support. In the meantime, revert the commit, especially as it was intended to be a non-functional change. Cc: Gavin Shan <gwshan@linux.vnet.ibm.com> Cc: Ian Munsie <imunsie@au1.ibm.com> Cc: Daniel Axtens <dja@axtens.net> Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/kernel/eeh_driver.c14
1 files changed, 4 insertions, 10 deletions
diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
index 80dfe89..8d14feb 100644
--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -590,16 +590,10 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus)
eeh_ops->configure_bridge(pe);
eeh_pe_restore_bars(pe);
- /*
- * If it's PHB PE, the frozen state on all available PEs should have
- * been cleared by the PHB reset. Otherwise, we unfreeze the PE and its
- * child PEs because they might be in frozen state.
- */
- if (!(pe->type & EEH_PE_PHB)) {
- rc = eeh_clear_pe_frozen_state(pe, false);
- if (rc)
- return rc;
- }
+ /* Clear frozen state */
+ rc = eeh_clear_pe_frozen_state(pe, false);
+ if (rc)
+ return rc;
/* Give the system 5 seconds to finish running the user-space
* hotplug shutdown scripts, e.g. ifdown for ethernet. Yes,