dmaengine: idxd: Set defaults for GRPCFG traffic class

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@intel.com>
Link: https://lore.kernel.org/r/162681373005.1968485.3761065664382799202.stgit@djiang5-desk3.ch.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

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

drivers/dma/idxd/idxd.h

@@ -16,6 +16,7 @@
 #define IDXD_DRIVER_VERSION	"1.00"
 
 extern struct kmem_cache *idxd_desc_pool;
+extern bool tc_override;
 
 struct idxd_wq;
 struct idxd_dev;

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;

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

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;