From 3e8aaacdad4f66641f87ab441fe644b45f8ebdff Mon Sep 17 00:00:00 2001 From: Robert Richter Date: Thu, 8 Jan 2026 11:13:23 +0100 Subject: [PATCH] cxl/port: Fix target list setup for multiple decoders sharing the same dport If a switch port has more than one decoder that is using the same downstream port, the enumeration of the target lists may fail with: # dmesg | grep target.list update_decoder_targets: cxl decoder1.0: dport3 found in target list, index 3 update_decoder_targets: cxl decoder1.0: dport2 found in target list, index 2 update_decoder_targets: cxl decoder1.0: dport0 found in target list, index 0 update_decoder_targets: cxl decoder2.0: dport3 found in target list, index 1 update_decoder_targets: cxl decoder4.0: dport3 found in target list, index 1 cxl_mem mem6: failed to find endpoint12:0000:00:01.4 in target list of decoder2.1 cxl_mem mem8: failed to find endpoint13:0000:20:01.4 in target list of decoder4.1 The case, that the same downstream port can be used in multiple target lists, is allowed and possible. Fix the update of the target list. Enumerate all children of the switch port and do not stop the iteration after the first matching target was found. With the fix applied: # dmesg | grep target.list update_decoder_targets: cxl decoder1.0: dport2 found in target list, index 2 update_decoder_targets: cxl decoder1.0: dport0 found in target list, index 0 update_decoder_targets: cxl decoder1.0: dport3 found in target list, index 3 update_decoder_targets: cxl decoder2.0: dport3 found in target list, index 1 update_decoder_targets: cxl decoder2.1: dport3 found in target list, index 1 update_decoder_targets: cxl decoder4.0: dport3 found in target list, index 1 update_decoder_targets: cxl decoder4.1: dport3 found in target list, index 1 Analyzing the conditions when this happens: 1) A dport is shared by multiple decoders. 2) The decoders have interleaving configured (ways > 1). The configuration above has the following hierarchy details (fixed version): root0 |_ | | | decoder0.1 | ways: 2 | target_list: 0,1 |_______________________________________ | | | dport0 | dport1 | | port2 port4 | | |___________________ |_____________________ | | | | | | | decoder2.0 decoder2.1 | decoder4.0 decoder4.1 | ways: 2 ways: 2 | ways: 2 ways: 2 | target_list: 2,3 target_list: 2,3 | target_list: 2,3 target_list: 2,3 |___________________ |___________________ | | | | | dport2 | dport3 | dport2 | dport3 | | | | endpoint7 endpoint12 endpoint9 endpoint13 |_ |_ |_ |_ | | | | | | | | | decoder7.0 | decoder12.0 | decoder9.0 | decoder13.0 | decoder7.2 | decoder12.2 | decoder9.2 | decoder13.2 | | | | mem3 mem5 mem6 mem8 Note: Device numbers vary for every boot. Current kernel fails to enumerate endpoint12 and endpoint13 as the target list is not updated for the second decoder. Fixes: 4f06d81e7c6a ("cxl: Defer dport allocation for switch ports") Reviewed-by: Dave Jiang Reviewed-by: Alison Schofield Reviewed-by: Jonathan Cameron Signed-off-by: Robert Richter Link: https://patch.msgid.link/20260108101324.509667-1-rrichter@amd.com Signed-off-by: Dave Jiang --- drivers/cxl/core/port.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index fef3aa0c6680..3310dbfae9d6 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -1590,7 +1590,7 @@ static int update_decoder_targets(struct device *dev, void *data) cxlsd->target[i] = dport; dev_dbg(dev, "dport%d found in target list, index %d\n", dport->port_id, i); - return 1; + return 0; } } -- 2.47.3