From: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
To: ray.jui@broadcom.com, helgaas@kernel.org, sbranden@broadcom.com,
f.fainelli@gmail.com, lorenzo.pieralisi@arm.com, robh@kernel.org
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
Subject: [PATCH v3 2/2] PCI: Reduce warnings on possible RW1C corruption
Date: Mon, 3 Aug 2020 15:52:41 +1200 [thread overview]
Message-ID: <20200803035241.7737-2-mark.tomlinson@alliedtelesis.co.nz> (raw)
In-Reply-To: <20200803035241.7737-1-mark.tomlinson@alliedtelesis.co.nz>
For hardware that only supports 32-bit writes to PCI there is the
possibility of clearing RW1C (write-one-to-clear) bits. A rate-limited
messages was introduced by fb2659230120, but rate-limiting is not the
best choice here. Some devices may not show the warnings they should if
another device has just produced a bunch of warnings. Also, the number
of messages can be a nuisance on devices which are otherwise working
fine.
This patch changes the ratelimit to a single warning per bus. This
ensures no bus is 'starved' of emitting a warning and also that there
isn't a continuous stream of warnings. It would be preferable to have a
warning per device, but the pci_dev structure is not available here, and
a lookup from devfn would be far too slow.
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Fixes: fb2659230120 ("PCI: Warn on possible RW1C corruption for sub-32 bit config writes")
Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
---
drivers/pci/access.c | 9 ++++++---
include/linux/pci.h | 1 +
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 79c4a2ef269a..ab85cb7df9b6 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -160,9 +160,12 @@ int pci_generic_config_write32(struct pci_bus *bus, unsigned int devfn,
* write happen to have any RW1C (write-one-to-clear) bits set, we
* just inadvertently cleared something we shouldn't have.
*/
- dev_warn_ratelimited(&bus->dev, "%d-byte config write to %04x:%02x:%02x.%d offset %#x may corrupt adjacent RW1C bits\n",
- size, pci_domain_nr(bus), bus->number,
- PCI_SLOT(devfn), PCI_FUNC(devfn), where);
+ if (!bus->unsafe_warn) {
+ dev_warn(&bus->dev, "%d-byte config write to %04x:%02x:%02x.%d offset %#x may corrupt adjacent RW1C bits\n",
+ size, pci_domain_nr(bus), bus->number,
+ PCI_SLOT(devfn), PCI_FUNC(devfn), where);
+ bus->unsafe_warn = true;
+ }
mask = ~(((1 << (size * 8)) - 1) << ((where & 0x3) * 8));
tmp = readl(addr) & mask;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 34c1c4f45288..5b6ab593ae09 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -613,6 +613,7 @@ struct pci_bus {
unsigned char primary; /* Number of primary bridge */
unsigned char max_bus_speed; /* enum pci_bus_speed */
unsigned char cur_bus_speed; /* enum pci_bus_speed */
+ bool unsafe_warn; /* warned about RW1C config write */
#ifdef CONFIG_PCI_DOMAINS_GENERIC
int domain_nr;
#endif
--
2.28.0
next prev parent reply other threads:[~2020-08-03 3:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-03 3:52 [PATCH v3 1/2] PCI: iproc: Set affinity mask on MSI interrupts Mark Tomlinson
2020-08-03 3:52 ` Mark Tomlinson [this message]
2020-08-05 22:48 ` Ray Jui
2020-09-07 16:16 ` Lorenzo Pieralisi
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