drivers/block/sx8: several minor changes
* Newer hardware doesn't corrupt data when the queue depth
is greater than one. Rather than force the user to recompile
with a greater queue depth, make it a module parameter.
* update copyright date
* add MODULE_VERSION()
* trim trailing whitespace
* move CARM_SG_BOUNDARY to a separate enum, since its unsigned long
* bump to version 1.0
diff --git a/drivers/block/sx8.c b/drivers/block/sx8.c
index d57007b9..b5f6126 100644
--- a/drivers/block/sx8.c
+++ b/drivers/block/sx8.c
@@ -1,7 +1,7 @@
/*
* sx8.c: Driver for Promise SATA SX8 looks-like-I2O hardware
*
- * Copyright 2004 Red Hat, Inc.
+ * Copyright 2004-2005 Red Hat, Inc.
*
* Author/maintainer: Jeff Garzik <jgarzik@pobox.com>
*
@@ -31,10 +31,6 @@
#include <asm/semaphore.h>
#include <asm/uaccess.h>
-MODULE_AUTHOR("Jeff Garzik");
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("Promise SATA SX8 block driver");
-
#if 0
#define CARM_DEBUG
#define CARM_VERBOSE_DEBUG
@@ -45,9 +41,35 @@
#undef CARM_NDEBUG
#define DRV_NAME "sx8"
-#define DRV_VERSION "0.8"
+#define DRV_VERSION "1.0"
#define PFX DRV_NAME ": "
+MODULE_AUTHOR("Jeff Garzik");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Promise SATA SX8 block driver");
+MODULE_VERSION(DRV_VERSION);
+
+/*
+ * SX8 hardware has a single message queue for all ATA ports.
+ * When this driver was written, the hardware (firmware?) would
+ * corrupt data eventually, if more than one request was outstanding.
+ * As one can imagine, having 8 ports bottlenecking on a single
+ * command hurts performance.
+ *
+ * Based on user reports, later versions of the hardware (firmware?)
+ * seem to be able to survive with more than one command queued.
+ *
+ * Therefore, we default to the safe option -- 1 command -- but
+ * allow the user to increase this.
+ *
+ * SX8 should be able to support up to ~60 queued commands (CARM_MAX_REQ),
+ * but problems seem to occur when you exceed ~30, even on newer hardware.
+ */
+static int max_queue = 1;
+module_param(max_queue, int, 0444);
+MODULE_PARM_DESC(max_queue, "Maximum number of queued commands. (min==1, max==30, safe==1)");
+
+
#define NEXT_RESP(idx) ((idx + 1) % RMSG_Q_LEN)
/* 0xf is just arbitrary, non-zero noise; this is sorta like poisoning */
@@ -90,12 +112,10 @@
/* command message queue limits */
CARM_MAX_REQ = 64, /* max command msgs per host */
- CARM_MAX_Q = 1, /* one command at a time */
CARM_MSG_LOW_WATER = (CARM_MAX_REQ / 4), /* refill mark */
/* S/G limits, host-wide and per-request */
CARM_MAX_REQ_SG = 32, /* max s/g entries per request */
- CARM_SG_BOUNDARY = 0xffffUL, /* s/g segment boundary */
CARM_MAX_HOST_SG = 600, /* max s/g entries per host */
CARM_SG_LOW_WATER = (CARM_MAX_HOST_SG / 4), /* re-fill mark */
@@ -181,6 +201,10 @@
FL_DYN_MAJOR = (1 << 17),
};
+enum {
+ CARM_SG_BOUNDARY = 0xffffUL, /* s/g segment boundary */
+};
+
enum scatter_gather_types {
SGT_32BIT = 0,
SGT_64BIT = 1,
@@ -448,7 +472,7 @@
for (i = 0; i < ARRAY_SIZE(msg_sizes); i++)
if (msg_size <= msg_sizes[i])
return i;
-
+
return -ENOENT;
}
@@ -509,7 +533,7 @@
if (host->hw_sg_used >= (CARM_MAX_HOST_SG - CARM_MAX_REQ_SG))
return NULL;
- for (i = 0; i < CARM_MAX_Q; i++)
+ for (i = 0; i < max_queue; i++)
if ((host->msg_alloc & (1ULL << i)) == 0) {
struct carm_request *crq = &host->req[i];
crq->port = NULL;
@@ -521,14 +545,14 @@
assert(host->n_msgs <= CARM_MAX_REQ);
return crq;
}
-
+
DPRINTK("no request available, returning NULL\n");
return NULL;
}
static int carm_put_request(struct carm_host *host, struct carm_request *crq)
{
- assert(crq->tag < CARM_MAX_Q);
+ assert(crq->tag < max_queue);
if (unlikely((host->msg_alloc & (1ULL << crq->tag)) == 0))
return -EINVAL; /* tried to clear a tag that was not active */
@@ -791,7 +815,7 @@
int is_ok)
{
carm_end_request_queued(host, crq, is_ok);
- if (CARM_MAX_Q == 1)
+ if (max_queue == 1)
carm_round_robin(host);
else if ((host->n_msgs <= CARM_MSG_LOW_WATER) &&
(host->hw_sg_used <= CARM_SG_LOW_WATER)) {
