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Subject[PATCH v2 16/17] staging: qlge: Refill rx buffers up to multiple of 16
Date
Reading the {s,l}bq_prod_idx registers on a running device, it appears that
the adapter will only use buffers up to prod_idx & 0xfff0. The driver
currently uses fixed-size guard zones (16 for sbq, 32 for lbq - don't know
why this difference). After the previous patch, this approach no longer
guarantees prod_idx values aligned on multiples of 16. While it appears
that we can write unaligned values to prod_idx without ill effects on
device operation, it makes more sense to change qlge_refill_bq() to refill
up to a limit that corresponds with the device's behavior.

Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
---
drivers/staging/qlge/qlge.h | 8 ++++++++
drivers/staging/qlge/qlge_main.c | 29 +++++++++++------------------
2 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/drivers/staging/qlge/qlge.h b/drivers/staging/qlge/qlge.h
index 7c48e333d29b..e5a352df8228 100644
--- a/drivers/staging/qlge/qlge.h
+++ b/drivers/staging/qlge/qlge.h
@@ -1423,6 +1423,9 @@ struct qlge_bq {
__le64 *base_indirect;
dma_addr_t base_indirect_dma;
struct qlge_bq_desc *queue;
+ /* prod_idx is the index of the first buffer that may NOT be used by
+ * hw, ie. one after the last. Advanced by sw.
+ */
void __iomem *prod_idx_db_reg;
/* next index where sw should refill a buffer for hw */
u16 next_to_use;
@@ -1442,6 +1445,11 @@ struct qlge_bq {
offsetof(struct rx_ring, lbq))); \
})

+/* Experience shows that the device ignores the low 4 bits of the tail index.
+ * Refill up to a x16 multiple.
+ */
+#define QLGE_BQ_ALIGN(index) ALIGN_DOWN(index, 16)
+
#define QLGE_BQ_WRAP(index) ((index) & (QLGE_BQ_LEN - 1))

struct rx_ring {
diff --git a/drivers/staging/qlge/qlge_main.c b/drivers/staging/qlge/qlge_main.c
index 83e75005688a..02ad0cdf4856 100644
--- a/drivers/staging/qlge/qlge_main.c
+++ b/drivers/staging/qlge/qlge_main.c
@@ -1114,22 +1114,12 @@ static void qlge_refill_bq(struct qlge_bq *bq)
struct rx_ring *rx_ring = QLGE_BQ_CONTAINER(bq);
struct ql_adapter *qdev = rx_ring->qdev;
struct qlge_bq_desc *bq_desc;
- int free_count, refill_count;
- unsigned int reserved_count;
+ int refill_count;
int i;

- if (bq->type == QLGE_SB)
- reserved_count = 16;
- else
- reserved_count = 32;
-
- free_count = bq->next_to_clean - bq->next_to_use;
- if (free_count <= 0)
- free_count += QLGE_BQ_LEN;
-
- refill_count = free_count - reserved_count;
- /* refill batch size */
- if (refill_count < 16)
+ refill_count = QLGE_BQ_WRAP(QLGE_BQ_ALIGN(bq->next_to_clean - 1) -
+ bq->next_to_use);
+ if (!refill_count)
return;

i = bq->next_to_use;
@@ -1164,11 +1154,14 @@ static void qlge_refill_bq(struct qlge_bq *bq)
i += QLGE_BQ_LEN;

if (bq->next_to_use != i) {
- netif_printk(qdev, rx_status, KERN_DEBUG, qdev->ndev,
- "ring %u %s: updating prod idx = %d.\n",
- rx_ring->cq_id, bq_type_name[bq->type], i);
+ if (QLGE_BQ_ALIGN(bq->next_to_use) != QLGE_BQ_ALIGN(i)) {
+ netif_printk(qdev, rx_status, KERN_DEBUG, qdev->ndev,
+ "ring %u %s: updating prod idx = %d.\n",
+ rx_ring->cq_id, bq_type_name[bq->type],
+ i);
+ ql_write_db_reg(i, bq->prod_idx_db_reg);
+ }
bq->next_to_use = i;
- ql_write_db_reg(bq->next_to_use, bq->prod_idx_db_reg);
}
}

--
2.23.0
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