[PATCH] dmaengine: idxd: Set defaults for GRPCFG traffic class

[Dave Jiang <dave.jiang@xxxxxxxxx>]

Set GRPCFG traffic class to value of 1 for best performance on current
generation of accelerators. Also add override option to allow experimentation.
Sysfs knobs are disabled for DSA/IAX gen1 devices.

Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
---
 Documentation/admin-guide/kernel-parameters.txt |    5 +++++
 drivers/dma/idxd/idxd.h                         |    1 +
 drivers/dma/idxd/init.c                         |   13 +++++++++++--
 drivers/dma/idxd/registers.h                    |    3 +++
 drivers/dma/idxd/sysfs.c                        |    6 ++++++
 5 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index bdb22006f713..ec5411cdec20 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1747,6 +1747,11 @@
 			support for the idxd driver. By default it is set to
 			true (1).
 
+	idxd.tc_override= [HW]
+			Format: <bool>
+			Allow override of default traffic class configuration
+			for the device. By default it is set to false (0).
+
 	ieee754=	[MIPS] Select IEEE Std 754 conformance mode
 			Format: { strict | legacy | 2008 | relaxed }
 			Default: strict
diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
index 34d4f43bfedc..94983bced189 100644
--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -17,6 +17,7 @@
 #define IDXD_DRIVER_VERSION	"1.00"
 
 extern struct kmem_cache *idxd_desc_pool;
+extern bool tc_override;
 
 struct idxd_wq;
 struct idxd_dev;
diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
index 8db56f98059f..eb09bc591c31 100644
--- a/drivers/dma/idxd/init.c
+++ b/drivers/dma/idxd/init.c
@@ -32,6 +32,10 @@ static bool sva = true;
 module_param(sva, bool, 0644);
 MODULE_PARM_DESC(sva, "Toggle SVA support on/off");
 
+bool tc_override;
+module_param(tc_override, bool, 0644);
+MODULE_PARM_DESC(tc_override, "Override traffic class defaults");
+
 #define DRV_NAME "idxd"
 
 bool support_enqcmd;
@@ -336,8 +340,13 @@ static int idxd_setup_groups(struct idxd_device *idxd)
 		}
 
 		idxd->groups[i] = group;
-		group->tc_a = -1;
-		group->tc_b = -1;
+		if (idxd->hw.version < DEVICE_VERSION_2 && !tc_override) {
+			group->tc_a = 1;
+			group->tc_b = 1;
+		} else {
+			group->tc_a = -1;
+			group->tc_b = -1;
+		}
 	}
 
 	return 0;
diff --git a/drivers/dma/idxd/registers.h b/drivers/dma/idxd/registers.h
index 7343a8f48819..ffc7550a77ee 100644
--- a/drivers/dma/idxd/registers.h
+++ b/drivers/dma/idxd/registers.h
@@ -7,6 +7,9 @@
 #define PCI_DEVICE_ID_INTEL_DSA_SPR0	0x0b25
 #define PCI_DEVICE_ID_INTEL_IAX_SPR0	0x0cfe
 
+#define DEVICE_VERSION_1		0x100
+#define DEVICE_VERSION_2		0x200
+
 #define IDXD_MMIO_BAR		0
 #define IDXD_WQ_BAR		2
 #define IDXD_PORTAL_SIZE	PAGE_SIZE
diff --git a/drivers/dma/idxd/sysfs.c b/drivers/dma/idxd/sysfs.c
index b883e9f16e7f..881a12596d4b 100644
--- a/drivers/dma/idxd/sysfs.c
+++ b/drivers/dma/idxd/sysfs.c
@@ -327,6 +327,9 @@ static ssize_t group_traffic_class_a_store(struct device *dev,
 	if (idxd->state == IDXD_DEV_ENABLED)
 		return -EPERM;
 
+	if (idxd->hw.version < DEVICE_VERSION_2 && !tc_override)
+		return -EPERM;
+
 	if (val < 0 || val > 7)
 		return -EINVAL;
 
@@ -366,6 +369,9 @@ static ssize_t group_traffic_class_b_store(struct device *dev,
 	if (idxd->state == IDXD_DEV_ENABLED)
 		return -EPERM;
 
+	if (idxd->hw.version < DEVICE_VERSION_2 && !tc_override)
+		return -EPERM;
+
 	if (val < 0 || val > 7)
 		return -EINVAL;