From: Manish Honap <[email protected]> media_ready was only ever set by cxl_pci, in advance of registering a memdev and with CXL Memory Device register assumptions. A consumer that creates a memdev without cxl_pci, such as a mailbox-less Type-2 accelerator brought up through devm_cxl_probe_mem(), therefore handed cxl_mem a device with media_ready still false, and cxl_mem_probe() rejected it with -EBUSY. __devm_cxl_add_memdev() turns that into -ENXIO back to the caller and the bind fails.
Move the readiness wait into cxl_mem_probe() so every memdev consumer gets a ready resource regardless of how the memdev was created. When media_ready is not already set, wait on the device's DVSEC Mem_Info_Valid and Mem_Active bits and mark it ready. cxl_pci keeps setting media_ready before it registers its memdev, so that path skips the wait. The CXL Memory Device register group is optional and many Type-2 devices do not implement it, so cxl_await_media_ready() must not read the Memdev Status register unless the group is mapped. Reading regs.memdev on a device that lacks it would fault. Gate that read on regs.memdev; the DVSEC bits already prove readiness for such devices. Signed-off-by: Manish Honap <[email protected]> --- drivers/cxl/core/pci.c | 15 +++++++++++---- drivers/cxl/mem.c | 9 +++++++-- 2 files changed, 18 insertions(+), 6 deletions(-) diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c index 08d4c955137d..9b372d5a1aa4 100644 --- a/drivers/cxl/core/pci.c +++ b/drivers/cxl/core/pci.c @@ -151,7 +151,6 @@ int cxl_await_media_ready(struct cxl_dev_state *cxlds) struct pci_dev *pdev = to_pci_dev(cxlds->dev); int d = cxlds->cxl_dvsec; int rc, i, hdm_count; - u64 md_status; u16 cap; rc = pci_read_config_word(pdev, @@ -172,9 +171,17 @@ int cxl_await_media_ready(struct cxl_dev_state *cxlds) return rc; } - md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET); - if (!CXLMDEV_READY(md_status)) - return -EIO; + /* + * It is possible some Type-2 devices (CXL_DEVTYPE_DEVMEM) do not + * implement regs.memdev; only consult the Memdev Status register when + * the group is actually present. + */ + if (cxlds->regs.memdev) { + u64 md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET); + + if (!CXLMDEV_READY(md_status)) + return -EIO; + } return 0; } diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c index 798e5c369cfc..9c6e99b9124c 100644 --- a/drivers/cxl/mem.c +++ b/drivers/cxl/mem.c @@ -105,8 +105,13 @@ static int cxl_mem_probe(struct device *dev) struct dentry *dentry; int rc; - if (!cxlds->media_ready) - return -EBUSY; + if (!cxlds->media_ready) { + rc = cxl_await_media_ready(cxlds); + if (rc) + return rc; + cxlds->media_ready = true; + dev_dbg(dev, "CXL media ready\n"); + } /* * Someone is trying to reattach this device after it lost its port -- 2.25.1
