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, 8 deletions

diff --git a/drivers/net/wireless/broadcom/b43/main.c b/drivers/net/wireless/broadcom/b43/main.c
index 74be3c809225..4c7980f84591 100644
--- a/drivers/net/wireless/broadcom/b43/main.c
+++ b/drivers/net/wireless/broadcom/b43/main.c
@@ -485,7 +485,6 @@ static void b43_ram_write(struct b43_wldev *dev, u16 offset, u32 val)
 		val = swab32(val);
 
 	b43_write32(dev, B43_MMIO_RAM_CONTROL, offset);
-	mmiowb();
 	b43_write32(dev, B43_MMIO_RAM_DATA, val);
 }
 
@@ -656,9 +655,7 @@ static void b43_tsf_write_locked(struct b43_wldev *dev, u64 tsf)
 	/* The hardware guarantees us an atomic write, if we
 	 * write the low register first. */
 	b43_write32(dev, B43_MMIO_REV3PLUS_TSF_LOW, low);
-	mmiowb();
 	b43_write32(dev, B43_MMIO_REV3PLUS_TSF_HIGH, high);
-	mmiowb();
 }
 
 void b43_tsf_write(struct b43_wldev *dev, u64 tsf)
@@ -1822,11 +1819,9 @@ static void b43_beacon_update_trigger_work(struct work_struct *work)
 		if (b43_bus_host_is_sdio(dev->dev)) {
 			/* wl->mutex is enough. */
 			b43_do_beacon_update_trigger_work(dev);
-			mmiowb();
 		} else {
 			spin_lock_irq(&wl->hardirq_lock);
 			b43_do_beacon_update_trigger_work(dev);
-			mmiowb();
 			spin_unlock_irq(&wl->hardirq_lock);
 		}
 	}
@@ -2078,7 +2073,6 @@ static irqreturn_t b43_interrupt_thread_handler(int irq, void *dev_id)
 
 	mutex_lock(&dev->wl->mutex);
 	b43_do_interrupt_thread(dev);
-	mmiowb();
 	mutex_unlock(&dev->wl->mutex);
 
 	return IRQ_HANDLED;
@@ -2143,7 +2137,6 @@ static irqreturn_t b43_interrupt_handler(int irq, void *dev_id)
 
 	spin_lock(&dev->wl->hardirq_lock);
 	ret = b43_do_interrupt(dev);
-	mmiowb();
 	spin_unlock(&dev->wl->hardirq_lock);
 
 	return ret;
diff --git a/drivers/net/wireless/broadcom/b43/sysfs.c b/drivers/net/wireless/broadcom/b43/sysfs.c
index 3190493bd07f..93d03b673670 100644
--- a/drivers/net/wireless/broadcom/b43/sysfs.c
+++ b/drivers/net/wireless/broadcom/b43/sysfs.c
@@ -129,7 +129,6 @@ static ssize_t b43_attr_interfmode_store(struct device *dev,
 	} else
 		err = -ENOSYS;
 
-	mmiowb();
 	mutex_unlock(&wldev->wl->mutex);
 
 	return err ? err : count;