From: Webb Scales <webbnh@xxxxxx>
Encapsulate the conditional predicate which tests for legacy controllers
in a separate function and rework the code comments.
Reviewed-by: Scott Teel <scott.teel@xxxxxxxx>
Signed-off-by: Webb Scales <webbnh@xxxxxx>
Signed-off-by: Don Brace <don.brace@xxxxxxxx>
---
drivers/scsi/hpsa.c | 30 +++++++++++++++++++++---------
1 file changed, 21 insertions(+), 9 deletions(-)
diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index ec2503a..08d96a9 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -3107,7 +3107,8 @@ out:
kfree(logdev_list);
}
-/* hpsa_scatter_gather takes a struct scsi_cmnd, (cmd), and does the pci
+/*
+ * hpsa_scatter_gather takes a struct scsi_cmnd, (cmd), and does the pci
* dma mapping and fills in the scatter gather entries of the
* hpsa command, cp.
*/
@@ -3165,7 +3166,7 @@ static int hpsa_scatter_gather(struct ctlr_info *h,
sglist_finished:
cp->Header.SGList = (u8) use_sg; /* no. SGs contig in this cmd */
- cp->Header.SGTotal = cpu_to_le16(use_sg); /* total sgs in this cmd list */
+ cp->Header.SGTotal = cpu_to_le16(use_sg); /* total sgs in cmd list */
return 0;
}
@@ -6162,6 +6163,15 @@ static void hpsa_get_max_perf_mode_cmds(struct ctlr_info *h)
}
}
+/* If the controller reports that the total max sg entries is greater than 512,
+ * then we know that chained SG blocks work. (Original smart arrays did not
+ * support chained SG blocks and would return zero for max sg entries.)
+ */
+static int hpsa_supports_chained_sg_blocks(struct ctlr_info *h)
+{
+ return h->maxsgentries > 512;
+}
+
/* Interrogate the hardware for some limits:
* max commands, max SG elements without chaining, and with chaining,
* SG chain block size, etc.
@@ -6172,18 +6182,20 @@ static void hpsa_find_board_params(struct ctlr_info *h)
h->nr_cmds = h->max_commands - 4; /* Allow room for some ioctls */
h->maxsgentries = readl(&(h->cfgtable->MaxScatterGatherElements));
h->fw_support = readl(&(h->cfgtable->misc_fw_support));
- /*
- * Limit in-command s/g elements to 32 save dma'able memory.
- * Howvever spec says if 0, use 31
- */
- h->max_cmd_sg_entries = 31;
- if (h->maxsgentries > 512) {
+ if (hpsa_supports_chained_sg_blocks(h)) {
+ /* Limit in-command s/g elements to 32 save dma'able memory. */
h->max_cmd_sg_entries = 32;
h->chainsize = h->maxsgentries - h->max_cmd_sg_entries;
h->maxsgentries--; /* save one for chain pointer */
} else {
- h->chainsize = 0;
+ /*
+ * Original smart arrays supported at most 31 s/g entries
+ * embedded inline in the command (trying to use more
+ * would lock up the controller)
+ */
+ h->max_cmd_sg_entries = 31;
h->maxsgentries = 31; /* default to traditional values */
+ h->chainsize = 0;
}
/* Find out what task management functions are supported and cache */
--
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