target/linux/generic/backport-6.1/729-17-v6.3-net-ethernet-mtk_wed-get-rid-of-queue-lock-for-tx-qu.patch

   1 From: Lorenzo Bianconi <lorenzo@kernel.org>
   2 Date: Thu, 12 Jan 2023 10:21:29 +0100
   3 Subject: [PATCH] net: ethernet: mtk_wed: get rid of queue lock for tx queue
   4
   5 Similar to MTK Wireless Ethernet Dispatcher (WED) MCU rx queue,
   6 we do not need to protect WED MCU tx queue with a spin lock since
   7 the tx queue is accessed in the two following routines:
   8 - mtk_wed_wo_queue_tx_skb():
   9   it is run at initialization and during mt7915 normal operation.
  10   Moreover MCU messages are serialized through MCU mutex.
  11 - mtk_wed_wo_queue_tx_clean():
  12   it runs just at mt7915 driver module unload when no more messages
  13   are sent to the MCU.
  14
  15 Remove tx queue spinlock.
  16
  17 Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
  18 Link: https://lore.kernel.org/r/7bd0337b2a13ab1a63673b7c03fd35206b3b284e.1673515140.git.lorenzo@kernel.org
  19 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
  20 ---
  21
  22 --- a/drivers/net/ethernet/mediatek/mtk_wed_wo.c
  23 +++ b/drivers/net/ethernet/mediatek/mtk_wed_wo.c
  24 @@ -258,7 +258,6 @@ mtk_wed_wo_queue_alloc(struct mtk_wed_wo
  25                        int n_desc, int buf_size, int index,
  26                        struct mtk_wed_wo_queue_regs *regs)
  27  {
  28 -       spin_lock_init(&q->lock);
  29         q->regs = *regs;
  30         q->n_desc = n_desc;
  31         q->buf_size = buf_size;
  32 @@ -290,7 +289,6 @@ mtk_wed_wo_queue_tx_clean(struct mtk_wed
  33         struct page *page;
  34         int i;
  35
  36 -       spin_lock_bh(&q->lock);
  37         for (i = 0; i < q->n_desc; i++) {
  38                 struct mtk_wed_wo_queue_entry *entry = &q->entry[i];
  39
  40 @@ -299,7 +297,6 @@ mtk_wed_wo_queue_tx_clean(struct mtk_wed
  41                 skb_free_frag(entry->buf);
  42                 entry->buf = NULL;
  43         }
  44 -       spin_unlock_bh(&q->lock);
  45
  46         if (!q->cache.va)
  47                 return;
  48 @@ -347,8 +344,6 @@ int mtk_wed_wo_queue_tx_skb(struct mtk_w
  49         int ret = 0, index;
  50         u32 ctrl;
  51
  52 -       spin_lock_bh(&q->lock);
  53 -
  54         q->tail = mtk_wed_mmio_r32(wo, q->regs.dma_idx);
  55         index = (q->head + 1) % q->n_desc;
  56         if (q->tail == index) {
  57 @@ -379,8 +374,6 @@ int mtk_wed_wo_queue_tx_skb(struct mtk_w
  58         mtk_wed_wo_queue_kick(wo, q, q->head);
  59         mtk_wed_wo_kickout(wo);
  60  out:
  61 -       spin_unlock_bh(&q->lock);
  62 -
  63         dev_kfree_skb(skb);
  64
  65         return ret;
  66 --- a/drivers/net/ethernet/mediatek/mtk_wed_wo.h
  67 +++ b/drivers/net/ethernet/mediatek/mtk_wed_wo.h
  68 @@ -211,7 +211,6 @@ struct mtk_wed_wo_queue {
  69         struct mtk_wed_wo_queue_regs regs;
  70
  71         struct page_frag_cache cache;
  72 -       spinlock_t lock;
  73
  74         struct mtk_wed_wo_queue_desc *desc;
  75         dma_addr_t desc_dma;