drivers: Remove explicit invocations of mmiowb()

mmiowb() is now implied by spin_unlock() on architectures that require
it, so there is no reason to call it from driver code. This patch was
generated using coccinelle:

	@mmiowb@
	@@
	- mmiowb();

and invoked as:

$ for d in drivers include/linux/qed sound; do \
spatch --include-headers --sp-file mmiowb.cocci --dir $d --in-place; done

NOTE: mmiowb() has only ever guaranteed ordering in conjunction with
spin_unlock(). However, pairing each mmiowb() removal in this patch with
the corresponding call to spin_unlock() is not at all trivial, so there
is a small chance that this change may regress any drivers incorrectly
relying on mmiowb() to order MMIO writes between CPUs using lock-free
synchronisation. If you've ended up bisecting to this commit, you can
reintroduce the mmiowb() calls using wmb() instead, which should restore
the old behaviour on all architectures other than some esoteric ia64
systems.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

2 files changed, 0 insertions, 10 deletions

diff --git a/drivers/ntb/hw/idt/ntb_hw_idt.c b/drivers/ntb/hw/idt/ntb_hw_idt.c
index 1dede87dd54f..dcf234680535 100644
--- a/drivers/ntb/hw/idt/ntb_hw_idt.c
+++ b/drivers/ntb/hw/idt/ntb_hw_idt.c
@@ -358,8 +358,6 @@ static void idt_sw_write(struct idt_ntb_dev *ndev,
 	iowrite32((u32)reg, ndev->cfgspc + (ptrdiff_t)IDT_NT_GASAADDR);
 	/* Put the new value of the register */
 	iowrite32(data, ndev->cfgspc + (ptrdiff_t)IDT_NT_GASADATA);
-	/* Make sure the PCIe transactions are executed */
-	mmiowb();
 	/* Unlock GASA registers operations */
 	spin_unlock_irqrestore(&ndev->gasa_lock, irqflags);
 }
@@ -750,7 +748,6 @@ static void idt_ntb_local_link_enable(struct idt_ntb_dev *ndev)
 	spin_lock_irqsave(&ndev->mtbl_lock, irqflags);
 	idt_nt_write(ndev, IDT_NT_NTMTBLADDR, ndev->part);
 	idt_nt_write(ndev, IDT_NT_NTMTBLDATA, mtbldata);
-	mmiowb();
 	spin_unlock_irqrestore(&ndev->mtbl_lock, irqflags);
 
 	/* Notify the peers by setting and clearing the global signal bit */
@@ -778,7 +775,6 @@ static void idt_ntb_local_link_disable(struct idt_ntb_dev *ndev)
 	spin_lock_irqsave(&ndev->mtbl_lock, irqflags);
 	idt_nt_write(ndev, IDT_NT_NTMTBLADDR, ndev->part);
 	idt_nt_write(ndev, IDT_NT_NTMTBLDATA, 0);
-	mmiowb();
 	spin_unlock_irqrestore(&ndev->mtbl_lock, irqflags);
 
 	/* Notify the peers by setting and clearing the global signal bit */
@@ -1339,7 +1335,6 @@ static int idt_ntb_peer_mw_set_trans(struct ntb_dev *ntb, int pidx, int widx,
 		idt_nt_write(ndev, IDT_NT_LUTLDATA, (u32)addr);
 		idt_nt_write(ndev, IDT_NT_LUTMDATA, (u32)(addr >> 32));
 		idt_nt_write(ndev, IDT_NT_LUTUDATA, data);
-		mmiowb();
 		spin_unlock_irqrestore(&ndev->lut_lock, irqflags);
 		/* Limit address isn't specified since size is fixed for LUT */
 	}
@@ -1393,7 +1388,6 @@ static int idt_ntb_peer_mw_clear_trans(struct ntb_dev *ntb, int pidx,
 		idt_nt_write(ndev, IDT_NT_LUTLDATA, 0);
 		idt_nt_write(ndev, IDT_NT_LUTMDATA, 0);
 		idt_nt_write(ndev, IDT_NT_LUTUDATA, 0);
-		mmiowb();
 		spin_unlock_irqrestore(&ndev->lut_lock, irqflags);
 	}
 
@@ -1812,7 +1806,6 @@ static int idt_ntb_peer_msg_write(struct ntb_dev *ntb, int pidx, int midx,
 	/* Set the route and send the data */
 	idt_sw_write(ndev, partdata_tbl[ndev->part].msgctl[midx], swpmsgctl);
 	idt_nt_write(ndev, ntdata_tbl.msgs[midx].out, msg);
-	mmiowb();
 	/* Unlock the messages routing table */
 	spin_unlock_irqrestore(&ndev->msg_locks[midx], irqflags);
 
diff --git a/drivers/ntb/test/ntb_perf.c b/drivers/ntb/test/ntb_perf.c
index 2a9d6b0d1f19..11a6cd374004 100644
--- a/drivers/ntb/test/ntb_perf.c
+++ b/drivers/ntb/test/ntb_perf.c
@@ -284,11 +284,9 @@ static int perf_spad_cmd_send(struct perf_peer *peer, enum perf_cmd cmd,
 		ntb_peer_spad_write(perf->ntb, peer->pidx,
 				    PERF_SPAD_HDATA(perf->gidx),
 				    upper_32_bits(data));
-		mmiowb();
 		ntb_peer_spad_write(perf->ntb, peer->pidx,
 				    PERF_SPAD_CMD(perf->gidx),
 				    cmd);
-		mmiowb();
 		ntb_peer_db_set(perf->ntb, PERF_SPAD_NOTIFY(peer->gidx));
 
 		dev_dbg(&perf->ntb->dev, "DB ring peer %#llx\n",
@@ -379,7 +377,6 @@ static int perf_msg_cmd_send(struct perf_peer *peer, enum perf_cmd cmd,
 
 		ntb_peer_msg_write(perf->ntb, peer->pidx, PERF_MSG_HDATA,
 				   upper_32_bits(data));
-		mmiowb();
 
 		/* This call shall trigger peer message event */
 		ntb_peer_msg_write(perf->ntb, peer->pidx, PERF_MSG_CMD, cmd);