Thread (18 messages) flat view 18 messages, 5 authors, 2021-05-17

Re: [PATCH 6/6] PCI: keystone: Add workaround for Errata #i2037 (AM65x SR 1.0)

From: Krzysztof Wilczyński <hidden>
Date: 2021-03-26 07:19:52
Also in: linux-arm-kernel, linux-pci, lkml

Hi Kishon,

A few small nitpicks.
Errata #i2037 in AM65x/DRA80xM Processors Silicon Revision 1.0
(SPRZ452D–July 2018–Revised December 2019 [1]) mentions when an
inbound PCIe TLP spans more than two internal AXI 128-byte bursts,
the bus may corrupt the packet payload and the corrupt data may
cause associated applications or the processor to hang.

The workaround for Errata #i2037 is to limit the maximum read
request size and maximum payload size to 128 Bytes. Add workaround
for Errata #i2037 here. The errata and workaround is applicable
only to AM65x SR 1.0 and later versions of the silicon will have
this fixed.
I think it would be either "128 B" or "128 bytes", there is no need to
capitalise bytes.

[...]
+	/*
+	 * Memory transactions fail with PCI controller in AM654 PG1.0
+	 * when MRRS is set to more than 128 Bytes. Force the MRRS to
+	 * 128 Bytes in all downstream devices.
+	 */
Same here, it would be "128 bytes" in the comment above.

[...]
+		if (pcie_get_readrq(dev) > 128) {
+			dev_info(&dev->dev, "limiting MRRS to 128\n");
+			pcie_set_readrq(dev, 128);
+		}
[...]

Might be nice to add unit here, so "128 bytes".

Krzysztof
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