From: Dan Williams dan.j.williams@intel.com
commit 8f0220af58c3b73e9041377a23708d37600b33c1 upstream.
commit eb0764b822b9 ("cxl/port: Enable the HDM decoder capability for switch ports")
...was added on the observation of CXL memory not being accessible after setting up a region on a "cold-plugged" device. A "cold-plugged" CXL device is one that was not present at boot, so platform-firmware/BIOS has no chance to set it up.
While it is true that the debug found the enable bit clear in the host-bridge's instance of the global control register (CXL 3.0 8.2.4.19.2 CXL HDM Decoder Global Control Register), that bit is described as:
"This bit is only applicable to CXL.mem devices and shall return 0 on CXL Host Bridges and Upstream Switch Ports."
So it is meant to be zero, and further testing confirmed that this "fix" had no effect on the failure. Revert it, and be more vigilant about proposed fixes in the future. Since the original copied stable@, flag this revert for stable@ as well.
Cc: stable@vger.kernel.org Fixes: eb0764b822b9 ("cxl/port: Enable the HDM decoder capability for switch ports") Reviewed-by: Jonathan Cameron Jonathan.Cameron@huawei.com Reviewed-by: Dave Jiang dave.jiang@intel.com Link: https://lore.kernel.org/r/168685882012.3475336.16733084892658264991.stgit@dw... Signed-off-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/cxl/core/pci.c | 27 ++++----------------------- drivers/cxl/cxl.h | 1 - drivers/cxl/port.c | 14 +++++--------- tools/testing/cxl/Kbuild | 1 - tools/testing/cxl/test/mock.c | 15 --------------- 5 files changed, 9 insertions(+), 49 deletions(-)
--- a/drivers/cxl/core/pci.c +++ b/drivers/cxl/core/pci.c @@ -308,36 +308,17 @@ static void disable_hdm(void *_cxlhdm) hdm + CXL_HDM_DECODER_CTRL_OFFSET); }
-int devm_cxl_enable_hdm(struct cxl_port *port, struct cxl_hdm *cxlhdm) +static int devm_cxl_enable_hdm(struct device *host, struct cxl_hdm *cxlhdm) { - void __iomem *hdm; + void __iomem *hdm = cxlhdm->regs.hdm_decoder; u32 global_ctrl;
- /* - * If the hdm capability was not mapped there is nothing to enable and - * the caller is responsible for what happens next. For example, - * emulate a passthrough decoder. - */ - if (IS_ERR(cxlhdm)) - return 0; - - hdm = cxlhdm->regs.hdm_decoder; global_ctrl = readl(hdm + CXL_HDM_DECODER_CTRL_OFFSET); - - /* - * If the HDM decoder capability was enabled on entry, skip - * registering disable_hdm() since this decode capability may be - * owned by platform firmware. - */ - if (global_ctrl & CXL_HDM_DECODER_ENABLE) - return 0; - writel(global_ctrl | CXL_HDM_DECODER_ENABLE, hdm + CXL_HDM_DECODER_CTRL_OFFSET);
- return devm_add_action_or_reset(&port->dev, disable_hdm, cxlhdm); + return devm_add_action_or_reset(host, disable_hdm, cxlhdm); } -EXPORT_SYMBOL_NS_GPL(devm_cxl_enable_hdm, CXL);
int cxl_dvsec_rr_decode(struct device *dev, int d, struct cxl_endpoint_dvsec_info *info) @@ -511,7 +492,7 @@ int cxl_hdm_decode_init(struct cxl_dev_s if (info->mem_enabled) return 0;
- rc = devm_cxl_enable_hdm(port, cxlhdm); + rc = devm_cxl_enable_hdm(&port->dev, cxlhdm); if (rc) return rc;
--- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -710,7 +710,6 @@ struct cxl_endpoint_dvsec_info { struct cxl_hdm; struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port, struct cxl_endpoint_dvsec_info *info); -int devm_cxl_enable_hdm(struct cxl_port *port, struct cxl_hdm *cxlhdm); int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm, struct cxl_endpoint_dvsec_info *info); int devm_cxl_add_passthrough_decoder(struct cxl_port *port); --- a/drivers/cxl/port.c +++ b/drivers/cxl/port.c @@ -60,17 +60,13 @@ static int discover_region(struct device static int cxl_switch_port_probe(struct cxl_port *port) { struct cxl_hdm *cxlhdm; - int rc, nr_dports; + int rc;
- nr_dports = devm_cxl_port_enumerate_dports(port); - if (nr_dports < 0) - return nr_dports; - - cxlhdm = devm_cxl_setup_hdm(port, NULL); - rc = devm_cxl_enable_hdm(port, cxlhdm); - if (rc) + rc = devm_cxl_port_enumerate_dports(port); + if (rc < 0) return rc;
+ cxlhdm = devm_cxl_setup_hdm(port, NULL); if (!IS_ERR(cxlhdm)) return devm_cxl_enumerate_decoders(cxlhdm, NULL);
@@ -79,7 +75,7 @@ static int cxl_switch_port_probe(struct return PTR_ERR(cxlhdm); }
- if (nr_dports == 1) { + if (rc == 1) { dev_dbg(&port->dev, "Fallback to passthrough decoder\n"); return devm_cxl_add_passthrough_decoder(port); } --- a/tools/testing/cxl/Kbuild +++ b/tools/testing/cxl/Kbuild @@ -6,7 +6,6 @@ ldflags-y += --wrap=acpi_pci_find_root ldflags-y += --wrap=nvdimm_bus_register ldflags-y += --wrap=devm_cxl_port_enumerate_dports ldflags-y += --wrap=devm_cxl_setup_hdm -ldflags-y += --wrap=devm_cxl_enable_hdm ldflags-y += --wrap=devm_cxl_add_passthrough_decoder ldflags-y += --wrap=devm_cxl_enumerate_decoders ldflags-y += --wrap=cxl_await_media_ready --- a/tools/testing/cxl/test/mock.c +++ b/tools/testing/cxl/test/mock.c @@ -149,21 +149,6 @@ struct cxl_hdm *__wrap_devm_cxl_setup_hd } EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_setup_hdm, CXL);
-int __wrap_devm_cxl_enable_hdm(struct cxl_port *port, struct cxl_hdm *cxlhdm) -{ - int index, rc; - struct cxl_mock_ops *ops = get_cxl_mock_ops(&index); - - if (ops && ops->is_mock_port(port->uport)) - rc = 0; - else - rc = devm_cxl_enable_hdm(port, cxlhdm); - put_cxl_mock_ops(index); - - return rc; -} -EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_enable_hdm, CXL); - int __wrap_devm_cxl_add_passthrough_decoder(struct cxl_port *port) { int rc, index;