@@ -219,46 +219,12 @@ static int cxl_pci_mbox_get(struct cxl_dev_state *cxlds)
mutex_lock_io(&cxlds->mbox_mutex);
- /*
- * XXX: There is some amount of ambiguity in the 2.0 version of the spec
- * around the mailbox interface ready (8.2.8.5.1.1). The purpose of the
- * bit is to allow firmware running on the device to notify the driver
- * that it's ready to receive commands. It is unclear if the bit needs
- * to be read for each transaction mailbox, ie. the firmware can switch
- * it on and off as needed. Second, there is no defined timeout for
- * mailbox ready, like there is for the doorbell interface.
- *
- * Assumptions:
- * 1. The firmware might toggle the Mailbox Interface Ready bit, check
- * it for every command.
- *
- * 2. If the doorbell is clear, the firmware should have first set the
- * Mailbox Interface Ready bit. Therefore, waiting for the doorbell
- * to be ready is sufficient.
- */
- rc = cxl_pci_mbox_wait_for_doorbell(cxlds);
- if (rc) {
- dev_warn(dev, "Mailbox interface not ready\n");
- goto out;
- }
-
- md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET);
- if (!(md_status & CXLMDEV_MBOX_IF_READY && CXLMDEV_READY(md_status))) {
- dev_err(dev, "mbox: reported doorbell ready, but not mbox ready\n");
- rc = -EBUSY;
- goto out;
- }
-
- /*
- * Hardware shouldn't allow a ready status but also have failure bits
- * set. Spit out an error, this should be a bug report
- */
rc = check_device_status(cxlds);
if (rc)
goto out;
if (CXLMDEV_RESET_NEEDED(md_status)) {
- dev_err(dev, "mbox: reported ready, but reset needed\n");
+ dev_err(dev, "mbox: reset needed\n");
rc = -EFAULT;
goto out;
}
The expectation is that the mailbox interface ready bit will be set at the start of any access through the mailbox interface. Therefore, waiting for the doorbell busy bit to be clear would imply that the mailbox interface is ready. The original driver implementation used the doorbell timeout for the Mailbox Interface Ready bit to piggyback off of, since the latter doesn't have a defined timeout (introduced in commit 8adaf747c9f0 ("cxl/mem: Find device capabilities"), a timeout has since been defined with an ECN to the 2.0 spec). With the current driver waiting for mailbox interface ready as a part of probe() it's no longer necessary to use the piggyback. With the piggybacking no longer necessary it doesn't make sense to check doorbell status when acquiring the mailbox. It will be checked during the normal mailbox exchange protocol. While here, make minor whitespace fix in the comment describing the behavior. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> (v1) Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> --- Changes since v1: Reword commit message (Jonathan) Drop comment block altogether (Dan) Don't check IF ready in mbox_get() (Dan) --- drivers/cxl/pci.c | 36 +----------------------------------- 1 file changed, 1 insertion(+), 35 deletions(-)