[PATCH net v3 1/2] net: ethernet: mtk_wed: skip ring reset in wdma_tx_ring_setup for WED v3

[PATCH net v3 1/2] net: ethernet: mtk_wed: skip ring reset in wdma_tx_ring_setup for WED v3

[Zhi-Jun You]

Currently WED v3 tx wdma ring, ring reset happens in a separate code
block unconditionally.

Moreover, v3 has double the size of wdma_desc and has different init
values. mtk_wed_ring_reset doens't deal with that and would corrupt the
wdma_desc.

Fix this by skipping mtk_wed_ring_reset in mtk_wdma_tx_ring_setup for
WED v3.

Fixes: e2f64db13aa1 ("net: ethernet: mtk_wed: introduce WED support for MT7988")
Signed-off-by: Zhi-Jun You <hujy652@gmail.com>
---
Changes in v3:
- new patch addressing WED v3 ring reset issue raised by Sashiko
- Link to the review: https://lore.kernel.org/netdev/20260630144831.1109-1-hujy652@gmail.com/
---
 drivers/net/ethernet/mediatek/mtk_wed.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_wed.c b/drivers/net/ethernet/mediatek/mtk_wed.c
index 10d9beaae372..7d2775a97fa0 100644
--- a/drivers/net/ethernet/mediatek/mtk_wed.c
+++ b/drivers/net/ethernet/mediatek/mtk_wed.c
@@ -1938,7 +1938,7 @@ mtk_wed_wdma_tx_ring_setup(struct mtk_wed_device *dev, int idx, int size,
 	wdma_w32(dev, MTK_WDMA_RING_TX(idx) + MTK_WED_RING_OFS_CPU_IDX, 0);
 	wdma_w32(dev, MTK_WDMA_RING_TX(idx) + MTK_WED_RING_OFS_DMA_IDX, 0);
 
-	if (reset)
+	if (!mtk_wed_is_v3_or_greater(dev->hw) && reset)
 		mtk_wed_ring_reset(wdma, MTK_WED_WDMA_RING_SIZE, true);
 
 	if (!idx)  {
-- 
2.47.3

[PATCH net v3 2/2] net:ethernet: mtk_wed: setup WDMA_RING_TX(0) for non-DBDC MT7986

[Zhi-Jun You]

WDMA_RING_TX(0) is required to set MTK_WED_WDMA_RING_TX for WED RX
but on a non-DBDC MT7986 it is never setup because idx is 1.

Setting MTK_WED_WDMA_RING_TX with WDMA_RING_TX(1) is not feasible because
WED still tries to send through WDMA_RING_TX(0). This is verified with
register dump.

Fix this by calling mtk_wed_wdma_tx_ring_setup if wed is v2 and
rx_ring[0] is not allocated and reset tx_wdma[0] if it's already
allocated.

Fixes: 4c5de09eb0d0 ("net: ethernet: mtk_wed: add configure wed wo support")
Signed-off-by: Zhi-Jun You <hujy652@gmail.com>
---
Changes in v3:
- no change
- Link to v2: https://lore.kernel.org/r/20260711112128.971-1-hujy652@gmail.com
Changes in v2:
- Address warm reset concern raised by AI review.
- Return value concern is skipped until further comment from reviewers.
- Added a comment to explain this special case.
- Link to v1: https://lore.kernel.org/r/20260630144831.1109-1-hujy652@gmail.com
---
 drivers/net/ethernet/mediatek/mtk_wed.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/mediatek/mtk_wed.c b/drivers/net/ethernet/mediatek/mtk_wed.c
index 7d2775a97fa0..b48abad995d7 100644
--- a/drivers/net/ethernet/mediatek/mtk_wed.c
+++ b/drivers/net/ethernet/mediatek/mtk_wed.c
@@ -2334,6 +2334,13 @@ mtk_wed_start(struct mtk_wed_device *dev, u32 irq_mask)
 		if (!dev->rx_wdma[i].desc)
 			mtk_wed_wdma_rx_ring_setup(dev, i, 16, false);
 
+	/*
+	 * non-DBDC MT7986 allocates only rx_ring[1] and tx_wdma[1] during setup
+	 * but tx_wdma[0] is also needed for WED to function.
+	 */
+	if (mtk_wed_is_v2(dev->hw) && !dev->rx_ring[0].desc)
+		mtk_wed_wdma_tx_ring_setup(dev, 0, MTK_WED_WDMA_RING_SIZE, !!dev->tx_wdma[0].desc);
+
 	if (dev->wlan.hw_rro) {
 		for (i = 0; i < MTK_WED_RX_PAGE_QUEUES; i++) {
 			u32 addr = MTK_WED_RRO_MSDU_PG_CTRL0(i) +
-- 
2.47.3

Re: [PATCH net v3 2/2] net:ethernet: mtk_wed: setup WDMA_RING_TX(0) for non-DBDC MT7986

[Paolo Abeni]

From: AI Reviewer <ai@example.com>

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.
Full review at: https://sashiko.dev/
---
--- Patch [2]: [PATCH net v3 2/2] net:ethernet: mtk_wed: setup WDMA_RING_TX(0) for non-DBDC MT7986 ---
commit 30cd2d1bc8bf876e5d201d631684431920a3f165
Author: Zhi-Jun You <hujy652@gmail.com>

net:ethernet: mtk_wed: setup WDMA_RING_TX(0) for non-DBDC MT7986

This commit fixes an issue on non-DBDC MT7986 where WDMA_RING_TX(0) is
never set up because idx is 1, even though it is required for WED RX to
function. It addresses this by explicitly calling mtk_wed_wdma_tx_ring_setup
if the WED version is v2 and rx_ring[0] is unallocated.

Link: https://lore.kernel.org/r/20260711112128.971-1-hujy652@gmail.com
Link: https://lore.kernel.org/r/20260630144831.1109-1-hujy652@gmail.com

> diff --git a/drivers/net/ethernet/mediatek/mtk_wed.c b/drivers/net/ethernet/mediatek/mtk_wed.c
> --- a/drivers/net/ethernet/mediatek/mtk_wed.c
> +++ b/drivers/net/ethernet/mediatek/mtk_wed.c
[ ... ]
> @@ -2334,6 +2334,13 @@ mtk_wed_start(struct mtk_wed_device *dev, u32 irq_mask)
>  		if (!dev->rx_wdma[i].desc)
>  			mtk_wed_wdma_rx_ring_setup(dev, i, 16, false);

[Severity: High]
This is a pre-existing issue, but does this code ignore the return value
from mtk_wed_wdma_rx_ring_setup()? 

If mtk_wed_ring_alloc() fails due to memory pressure, it returns an error
without configuring the hardware base registers. Because the error is
ignored, when DMA is later enabled in mtk_wed_start(), could the hardware
attempt to fetch from unmapped physical addresses and cause an IOMMU fault?

>  
> +	/*
> +	 * non-DBDC MT7986 allocates only rx_ring[1] and tx_wdma[1] during setup
> +	 * but tx_wdma[0] is also needed for WED to function.
> +	 */
> +	if (mtk_wed_is_v2(dev->hw) && !dev->rx_ring[0].desc)
> +		mtk_wed_wdma_tx_ring_setup(dev, 0, MTK_WED_WDMA_RING_SIZE, !!dev->tx_wdma[0].desc);

[Severity: High]
Does this new call to mtk_wed_wdma_tx_ring_setup() also need to check its
return value? 

Similar to the RX ring above, if mtk_wed_ring_alloc() fails to allocate
memory, the hardware base registers won't be configured. Since the caller
proceeds to enable hardware DMA regardless, might this lead to the WED
processing descriptors from unmapped memory and causing memory corruption
or a system crash?

> +
>  	if (dev->wlan.hw_rro) {
>  		for (i = 0; i < MTK_WED_RX_PAGE_QUEUES; i++) {
-- 
This is an AI-generated review.