2020-09-08 21:19:58

by Felix Fietkau

[permalink] [raw]
Subject: [PATCH 07/11] mt76: dma: cache dma map address/len in struct mt76_queue_entry

Accessing them from uncached memory can be expensive, so it's cheaper to
cache them

Signed-off-by: Felix Fietkau <[email protected]>
---
drivers/net/wireless/mediatek/mt76/dma.c | 43 +++++++++++------------
drivers/net/wireless/mediatek/mt76/mt76.h | 2 ++
2 files changed, 22 insertions(+), 23 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c
index 7f669a2432a4..38cc40c99ba1 100644
--- a/drivers/net/wireless/mediatek/mt76/dma.c
+++ b/drivers/net/wireless/mediatek/mt76/dma.c
@@ -49,6 +49,7 @@ mt76_dma_add_buf(struct mt76_dev *dev, struct mt76_queue *q,
struct mt76_queue_buf *buf, int nbufs, u32 info,
struct sk_buff *skb, void *txwi)
{
+ struct mt76_queue_entry *entry;
struct mt76_desc *desc;
u32 ctrl;
int i, idx = -1;
@@ -61,16 +62,27 @@ mt76_dma_add_buf(struct mt76_dev *dev, struct mt76_queue *q,
for (i = 0; i < nbufs; i += 2, buf += 2) {
u32 buf0 = buf[0].addr, buf1 = 0;

+ idx = q->head;
+ q->head = (q->head + 1) % q->ndesc;
+
+ desc = &q->desc[idx];
+ entry = &q->entry[idx];
+
if (buf[0].skip_unmap)
- q->entry[q->head].skip_buf0 = true;
- q->entry[q->head].skip_buf1 = i == nbufs - 1;
+ entry->skip_buf0 = true;
+ entry->skip_buf1 = i == nbufs - 1;
+
+ entry->dma_addr[0] = buf[0].addr;
+ entry->dma_len[0] = buf[0].len;

ctrl = FIELD_PREP(MT_DMA_CTL_SD_LEN0, buf[0].len);
if (i < nbufs - 1) {
+ entry->dma_addr[1] = buf[1].addr;
+ entry->dma_len[1] = buf[1].len;
buf1 = buf[1].addr;
ctrl |= FIELD_PREP(MT_DMA_CTL_SD_LEN1, buf[1].len);
if (buf[1].skip_unmap)
- q->entry[q->head].skip_buf1 = true;
+ entry->skip_buf1 = true;
}

if (i == nbufs - 1)
@@ -78,11 +90,6 @@ mt76_dma_add_buf(struct mt76_dev *dev, struct mt76_queue *q,
else if (i == nbufs - 2)
ctrl |= MT_DMA_CTL_LAST_SEC1;

- idx = q->head;
- q->head = (q->head + 1) % q->ndesc;
-
- desc = &q->desc[idx];
-
WRITE_ONCE(desc->buf0, cpu_to_le32(buf0));
WRITE_ONCE(desc->buf1, cpu_to_le32(buf1));
WRITE_ONCE(desc->info, cpu_to_le32(info));
@@ -102,24 +109,14 @@ mt76_dma_tx_cleanup_idx(struct mt76_dev *dev, struct mt76_queue *q, int idx,
struct mt76_queue_entry *prev_e)
{
struct mt76_queue_entry *e = &q->entry[idx];
- __le32 __ctrl = READ_ONCE(q->desc[idx].ctrl);
- u32 ctrl = le32_to_cpu(__ctrl);
-
- if (!e->skip_buf0) {
- __le32 addr = READ_ONCE(q->desc[idx].buf0);
- u32 len = FIELD_GET(MT_DMA_CTL_SD_LEN0, ctrl);

- dma_unmap_single(dev->dev, le32_to_cpu(addr), len,
+ if (!e->skip_buf0)
+ dma_unmap_single(dev->dev, e->dma_addr[0], e->dma_len[0],
DMA_TO_DEVICE);
- }
-
- if (!e->skip_buf1) {
- __le32 addr = READ_ONCE(q->desc[idx].buf1);
- u32 len = FIELD_GET(MT_DMA_CTL_SD_LEN1, ctrl);

- dma_unmap_single(dev->dev, le32_to_cpu(addr), len,
+ if (!e->skip_buf1)
+ dma_unmap_single(dev->dev, e->dma_addr[1], e->dma_len[1],
DMA_TO_DEVICE);
- }

if (e->txwi == DMA_DUMMY_DATA)
e->txwi = NULL;
@@ -207,7 +204,7 @@ mt76_dma_get_buf(struct mt76_dev *dev, struct mt76_queue *q, int idx,
void *buf = e->buf;
int buf_len = SKB_WITH_OVERHEAD(q->buf_size);

- buf_addr = le32_to_cpu(READ_ONCE(desc->buf0));
+ buf_addr = e->dma_addr[0];
if (len) {
u32 ctl = le32_to_cpu(READ_ONCE(desc->ctrl));
*len = FIELD_GET(MT_DMA_CTL_SD_LEN0, ctl);
diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
index 2d44fe522ade..9dbb7dd65d23 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -102,6 +102,8 @@ struct mt76_queue_entry {
struct urb *urb;
int buf_sz;
};
+ u32 dma_addr[2];
+ u16 dma_len[2];
u16 wcid;
bool skip_buf0:1;
bool skip_buf1:1;
--
2.28.0