From: John Garry john.garry@huawei.com
[ Upstream commit cec9771d2e954650095aa37a6a97722c8194e7d2 ]
+----------+ +----------+ | | | | | |--- 3.0 G ---| |--- 6.0 G --- SAS disk | | | | | |--- 3.0 G ---| |--- 6.0 G --- SAS disk |initiator | | | | device |--- 3.0 G ---| Expander |--- 6.0 G --- SAS disk | | | | | |--- 3.0 G ---| |--- 6.0 G --- SATA disk -->failed to connect | | | | | | | |--- 6.0 G --- SATA disk -->failed to connect | | | | +----------+ +----------+
According to Serial Attached SCSI - 1.1 (SAS-1.1): If an expander PHY attached to a SATA PHY is using a physical link rate greater than the maximum connection rate supported by the pathway from an STP initiator port, a management application client should use the SMP PHY CONTROL function (see 10.4.3.10) to set the PROGRAMMED MAXIMUM PHYSICAL LINK RATE field of the expander PHY to the maximum connection rate supported by the pathway from that STP initiator port.
Currently libsas does not support checking if this condition occurs, nor rectifying when it does.
Such a condition is not at all common, however it has been seen on some pre-silicon environments where the initiator PHY only supports a 1.5 Gbit maximum linkrate, mated with 12G expander PHYs and 3/6G SATA phy.
This patch adds support for checking and rectifying this condition during initial device discovery only.
We do support checking min pathway connection rate during revalidation phase, when new devices can be detected in the topology. However we do not support in the case of the the user reprogramming PHY linkrates, such that min pathway condition is not met/maintained.
A note on root port PHY rates: The libsas root port PHY rates calculation is broken. Libsas sets the rates (min, max, and current linkrate) of a root port to the same linkrate of the first PHY member of that same port. In doing so, it assumes that all other PHYs which subsequently join the port to have the same negotiated linkrate, when they could actually be different.
In practice this doesn't happen, as initiator and expander PHYs are normally initialised with consistent min/max linkrates.
This has not caused an issue so far, so leave alone for now.
Tested-by: Jian Luo luojian5@huawei.com Signed-off-by: John Garry john.garry@huawei.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/libsas/sas_expander.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)
diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c index 259ee0d3c3e61..819a655473588 100644 --- a/drivers/scsi/libsas/sas_expander.c +++ b/drivers/scsi/libsas/sas_expander.c @@ -817,6 +817,26 @@ static struct domain_device *sas_ex_discover_end_dev(
#ifdef CONFIG_SCSI_SAS_ATA if ((phy->attached_tproto & SAS_PROTOCOL_STP) || phy->attached_sata_dev) { + if (child->linkrate > parent->min_linkrate) { + struct sas_phy_linkrates rates = { + .maximum_linkrate = parent->min_linkrate, + .minimum_linkrate = parent->min_linkrate, + }; + int ret; + + pr_notice("ex %016llx phy%02d SATA device linkrate > min pathway connection rate, attempting to lower device linkrate\n", + SAS_ADDR(child->sas_addr), phy_id); + ret = sas_smp_phy_control(parent, phy_id, + PHY_FUNC_LINK_RESET, &rates); + if (ret) { + pr_err("ex %016llx phy%02d SATA device could not set linkrate (%d)\n", + SAS_ADDR(child->sas_addr), phy_id, ret); + goto out_free; + } + pr_notice("ex %016llx phy%02d SATA device set linkrate successfully\n", + SAS_ADDR(child->sas_addr), phy_id); + child->linkrate = child->min_linkrate; + } res = sas_get_ata_info(child, phy); if (res) goto out_free;