https://github.com/torvalds/linux
Revision e4f6dfa9ef756a3934a4caf618b1e86e9e8e21d0 authored by Dan Williams on 04 November 2022, 00:30:54 UTC, committed by Dan Williams on 04 November 2022, 23:01:24 UTC
When programming port decode targets, the algorithm wants to ensure that two devices are compatible to be programmed as peers beneath a given port. A compatible peer is a target that shares the same dport, and where that target's interleave position also routes it to the same dport. Compatibility is determined by the device's interleave position being >= to distance. For example, if a given dport can only map every Nth position then positions less than N away from the last target programmed are incompatible. The @distance for the host-bridge's cxl_port in a simple dual-ported host-bridge configuration with 2 direct-attached devices is 1, i.e. An x2 region divided by 2 dports to reach 2 region targets. An x4 region under an x2 host-bridge would need 2 intervening switches where the @distance at the host bridge level is 2 (x4 region divided by 2 switches to reach 4 devices). However, the distance between peers underneath a single ported host-bridge is always zero because there is no limit to the number of devices that can be mapped. In other words, there are no decoders to program in a passthrough, all descendants are mapped and distance only starts matters for the intervening descendant ports of the passthrough port. Add tracking for the number of dports mapped to a port, and use that to detect the passthrough case for calculating @distance. Cc: <stable@vger.kernel.org> Reported-by: Bobo WL <lmw.bobo@gmail.com> Reported-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Link: http://lore.kernel.org/r/20221010172057.00001559@huawei.com Fixes: 27b3f8d13830 ("cxl/region: Program target lists") Reviewed-by: Vishal Verma <vishal.l.verma@intel.com> Link: https://lore.kernel.org/r/166752185440.947915.6617495912508299445.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
1 parent e41c845
Tip revision: e4f6dfa9ef756a3934a4caf618b1e86e9e8e21d0 authored by Dan Williams on 04 November 2022, 00:30:54 UTC
cxl/region: Fix 'distance' calculation with passthrough ports
cxl/region: Fix 'distance' calculation with passthrough ports
Tip revision: e4f6dfa
File | Mode | Size |
---|---|---|
Documentation | ||
LICENSES | ||
arch | ||
block | ||
certs | ||
crypto | ||
drivers | ||
fs | ||
include | ||
init | ||
io_uring | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
rust | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | -rw-r--r-- | 19.9 KB |
.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 151 bytes |
.gitattributes | -rw-r--r-- | 62 bytes |
.gitignore | -rw-r--r-- | 2.0 KB |
.mailmap | -rw-r--r-- | 24.0 KB |
.rustfmt.toml | -rw-r--r-- | 369 bytes |
COPYING | -rw-r--r-- | 496 bytes |
CREDITS | -rw-r--r-- | 99.1 KB |
Kbuild | -rw-r--r-- | 2.5 KB |
Kconfig | -rw-r--r-- | 555 bytes |
MAINTAINERS | -rw-r--r-- | 671.9 KB |
Makefile | -rw-r--r-- | 69.0 KB |
README | -rw-r--r-- | 727 bytes |
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...