From dc9c41bd9ece090b54eb8f1bbdfb1930e10d3ae7 Mon Sep 17 00:00:00 2001 From: Andrew Donnellan Date: Tue, 8 Dec 2015 16:59:25 +1100 Subject: [PATCH] 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 Cc: Ian Munsie Cc: Daniel Axtens Signed-off-by: Andrew Donnellan Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/eeh_driver.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c index 80dfe8965df9..8d14feb40f12 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, -- 2.30.2