From: Dave Jiang Date: Fri, 29 Aug 2025 18:09:19 +0000 (-0700) Subject: cxl: Add helper to detect top of CXL device topology X-Git-Tag: v6.18-rc1~85^2^2~9 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4fde89539a18d39169a511fda00db65eeba1a8e0;p=thirdparty%2Fkernel%2Flinux.git cxl: Add helper to detect top of CXL device topology Add a helper to replace the open code detection of CXL device hierarchy root, or the host bridge. The helper will be used for delayed downstream port (dport) creation. Reviewed-by: Jonathan Cameron Reviewed-by: Li Ming Reviewed-by: Dan Williams Reviewed-by: Alison Schofield Reviewed-by: Robert Richter Tested-by: Robert Richter Signed-off-by: Dave Jiang --- diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index 29197376b18e3..855623cebd7d0 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -33,6 +33,15 @@ static DEFINE_IDA(cxl_port_ida); static DEFINE_XARRAY(cxl_root_buses); +/* + * The terminal device in PCI is NULL and @platform_bus + * for platform devices (for cxl_test) + */ +static bool is_cxl_host_bridge(struct device *dev) +{ + return (!dev || dev == &platform_bus); +} + int cxl_num_decoders_committed(struct cxl_port *port) { lockdep_assert_held(&cxl_rwsem.region); @@ -1541,7 +1550,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd, resource_size_t component_reg_phys; int rc; - if (!dparent) { + if (is_cxl_host_bridge(dparent)) { /* * The iteration reached the topology root without finding the * CXL-root 'cxl_port' on a previous iteration, fail for now to @@ -1629,11 +1638,7 @@ retry: struct device *uport_dev; struct cxl_dport *dport; - /* - * The terminal "grandparent" in PCI is NULL and @platform_bus - * for platform devices - */ - if (!dport_dev || dport_dev == &platform_bus) + if (is_cxl_host_bridge(dport_dev)) return 0; uport_dev = dport_dev->parent;