[PATCH 0/3] libsas: SATA PHY connection rate matching during disovery

[PATCH 0/3] libsas: SATA PHY connection rate matching during disovery

[John Garry]

This patchset looks to resolve an issue we see whereby a SATA end device
negotiated linkrate may exceed the min linkrate to the initiator, and
not be able to establish a connection.

According to the SAS spec, we should lower the SATA PHY linkrate when this
condition occurs.

It appears that some SAS HBAs (whose driver do not use libsas) already do
this automatically (via firmware, I assume).

This patchset solves this issue during device discovery phase when
detecting a new device, but not during revalidation after the user has
reprogrammed some PHY linkrates in the topology. Solving for the latter is
much more complicated, and will be done as follow-up to this series.

A minor tidy-up to libsas.h is also included.

John Garry (3):
  scsi: libsas: Fix some indentation in libsas.h
  scsi: libsas: Check SMP PHY control function result
  scsi: libsas: Support SATA PHY connection rate unmatch fixing during
    discovery

 drivers/scsi/libsas/sas_expander.c | 29 +++++++++++++++++++-
 include/scsi/libsas.h              | 56 ++++++++++++++++++--------------------
 2 files changed, 55 insertions(+), 30 deletions(-)

-- 
1.9.1

[PATCH 1/3] scsi: libsas: Fix some indentation in libsas.h

[John Garry]

Currently much indentation in this file is done with whitespaces instead
of tabs, which can make reading difficult, so fix this up.

Some other little minor tidy-up is done, but this file still has many
other checkpatch warnings (generally linelength > 80 or function
arguments have no identifier names).

All libsas code can be audited for checkpatch issues later.

Signed-off-by: John Garry <john.garry@huawei.com>
---
 include/scsi/libsas.h | 56 +++++++++++++++++++++++++--------------------------
 1 file changed, 27 insertions(+), 29 deletions(-)

diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 3de3b10..857086c 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -52,8 +52,8 @@ enum sas_phy_role {
 };
 
 enum sas_phy_type {
-        PHY_TYPE_PHYSICAL,
-        PHY_TYPE_VIRTUAL
+	PHY_TYPE_PHYSICAL,
+	PHY_TYPE_VIRTUAL
 };
 
 /* The events are mnemonically described in sas_dump.c
@@ -91,7 +91,7 @@ enum discover_event {
 
 #define to_dom_device(_obj) container_of(_obj, struct domain_device, dev_obj)
 #define to_dev_attr(_attr)  container_of(_attr, struct domain_dev_attribute,\
-                                         attr)
+					 attr)
 
 enum routing_attribute {
 	DIRECT_ROUTING,
@@ -184,37 +184,37 @@ struct domain_device {
 	spinlock_t done_lock;
 	enum sas_device_type dev_type;
 
-        enum sas_linkrate linkrate;
-        enum sas_linkrate min_linkrate;
-        enum sas_linkrate max_linkrate;
+	enum sas_linkrate linkrate;
+	enum sas_linkrate min_linkrate;
+	enum sas_linkrate max_linkrate;
 
-        int  pathways;
+	int  pathways;
 
-        struct domain_device *parent;
-        struct list_head siblings; /* devices on the same level */
-        struct asd_sas_port *port;        /* shortcut to root of the tree */
+	struct domain_device *parent;
+	struct list_head siblings; /* devices on the same level */
+	struct asd_sas_port *port;        /* shortcut to root of the tree */
 	struct sas_phy *phy;
 
-        struct list_head dev_list_node;
+	struct list_head dev_list_node;
 	struct list_head disco_list_node; /* awaiting probe or destruct */
 
-        enum sas_protocol    iproto;
-        enum sas_protocol    tproto;
+	enum sas_protocol    iproto;
+	enum sas_protocol    tproto;
 
-        struct sas_rphy *rphy;
+	struct sas_rphy *rphy;
 
-        u8  sas_addr[SAS_ADDR_SIZE];
-        u8  hashed_sas_addr[HASHED_SAS_ADDR_SIZE];
+	u8  sas_addr[SAS_ADDR_SIZE];
+	u8  hashed_sas_addr[HASHED_SAS_ADDR_SIZE];
 
-        u8  frame_rcvd[32];
+	u8  frame_rcvd[32];
 
-        union {
-                struct expander_device ex_dev;
-                struct sata_device     sata_dev; /* STP & directly attached */
+	union {
+		struct expander_device ex_dev;
+		struct sata_device     sata_dev; /* STP & directly attached */
 		struct ssp_device      ssp_dev;
-        };
+	};
 
-        void *lldd_dev;
+	void *lldd_dev;
 	unsigned long state;
 	struct kref kref;
 };
@@ -512,10 +512,10 @@ enum exec_status {
 
 /* When a task finishes with a response, the LLDD examines the
  * response:
- * 	- For an ATA task task_status_struct::stat is set to
+ *	- For an ATA task task_status_struct::stat is set to
  * SAS_PROTO_RESPONSE, and the task_status_struct::buf is set to the
  * contents of struct ata_task_resp.
- * 	- For SSP tasks, if no data is present or status/TMF response
+ *	- For SSP tasks, if no data is present or status/TMF response
  * is valid, task_status_struct::stat is set.  If data is present
  * (SENSE data), the LLDD copies up to SAS_STATUS_BUF_SIZE, sets
  * task_status_struct::buf_valid_size, and task_status_struct::stat is
@@ -671,15 +671,13 @@ struct sas_domain_function_template {
 extern void sas_resume_ha(struct sas_ha_struct *sas_ha);
 extern void sas_suspend_ha(struct sas_ha_struct *sas_ha);
 
-int sas_set_phy_speed(struct sas_phy *phy,
-		      struct sas_phy_linkrates *rates);
+int sas_set_phy_speed(struct sas_phy *phy, struct sas_phy_linkrates *rates);
 int sas_phy_reset(struct sas_phy *phy, int hard_reset);
-extern int sas_queuecommand(struct Scsi_Host * ,struct scsi_cmnd *);
+extern int sas_queuecommand(struct Scsi_Host *, struct scsi_cmnd *);
 extern int sas_target_alloc(struct scsi_target *);
 extern int sas_slave_configure(struct scsi_device *);
 extern int sas_change_queue_depth(struct scsi_device *, int new_depth);
-extern int sas_bios_param(struct scsi_device *,
-			  struct block_device *,
+extern int sas_bios_param(struct scsi_device *, struct block_device *,
 			  sector_t capacity, int *hsc);
 extern struct scsi_transport_template *
 sas_domain_attach_transport(struct sas_domain_function_template *);
-- 
1.9.1

[PATCH 2/3] scsi: libsas: Check SMP PHY control function result

[John Garry]

Currently the SMP PHY control execution result is checked, however the
function result for the command is not.

As such, we may be missing all potential errors, like SMP FUNCTION FAILED,
INVALID REQUEST FRAME LENGTH, etc., meaning the PHY control request has
failed.

In some scenarios we need to ensure the function result is accepted, so
add a check for this.

Tested-by: Jian Luo <luojian5@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/scsi/libsas/sas_expander.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 17eb418..8817b8e 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -614,7 +614,14 @@ int sas_smp_phy_control(struct domain_device *dev, int phy_id,
 	}
 
 	res = smp_execute_task(dev, pc_req, PC_REQ_SIZE, pc_resp,PC_RESP_SIZE);
-
+	if (res) {
+		pr_err("ex %016llx phy%02d PHY control failed: %d\n",
+		       SAS_ADDR(dev->sas_addr), phy_id, res);
+	} else if (pc_resp[2] != SMP_RESP_FUNC_ACC) {
+		pr_err("ex %016llx phy%02d PHY control failed: function result 0x%x\n",
+		       SAS_ADDR(dev->sas_addr), phy_id, pc_resp[2]);
+		res = pc_resp[2];
+	}
 	kfree(pc_resp);
 	kfree(pc_req);
 	return res;
-- 
1.9.1

[PATCH 3/3] scsi: libsas: Support SATA PHY connection rate unmatch fixing during discovery

[John Garry]

   +----------+             +----------+
   |          |             |          |
   |          |--- 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>
---
 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 8817b8e..83e3715 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -824,6 +824,26 @@ 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;
-- 
1.9.1

Re: [PATCH 0/3] libsas: SATA PHY connection rate matching during disovery

[Martin K. Petersen]

John,

> This patchset looks to resolve an issue we see whereby a SATA end device
> negotiated linkrate may exceed the min linkrate to the initiator, and
> not be able to establish a connection.

Looks good to me. Applied to 5.1/scsi-queue. Thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering