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>

6 files changed, 0 insertions, 11 deletions

diff --git a/drivers/staging/comedi/drivers/mite.c b/drivers/staging/comedi/drivers/mite.c
index 61e03ad84123..639ec1586976 100644
--- a/drivers/staging/comedi/drivers/mite.c
+++ b/drivers/staging/comedi/drivers/mite.c
@@ -371,7 +371,6 @@ static unsigned int mite_get_status(struct mite_channel *mite_chan)
 		writel(CHOR_CLRDONE,
 		       mite->mmio + MITE_CHOR(mite_chan->channel));
 	}
-	mmiowb();
 	spin_unlock_irqrestore(&mite->lock, flags);
 	return status;
 }
@@ -451,7 +450,6 @@ void mite_dma_arm(struct mite_channel *mite_chan)
 	mite_chan->done = 0;
 	/* arm */
 	writel(CHOR_START, mite->mmio + MITE_CHOR(mite_chan->channel));
-	mmiowb();
 	spin_unlock_irqrestore(&mite->lock, flags);
 }
 EXPORT_SYMBOL_GPL(mite_dma_arm);
@@ -638,7 +636,6 @@ void mite_release_channel(struct mite_channel *mite_chan)
 		       CHCR_CLR_LC_IE | CHCR_CLR_CONT_RB_IE,
 		       mite->mmio + MITE_CHCR(mite_chan->channel));
 		mite_chan->ring = NULL;
-		mmiowb();
 	}
 	spin_unlock_irqrestore(&mite->lock, flags);
 }
diff --git a/drivers/staging/comedi/drivers/ni_660x.c b/drivers/staging/comedi/drivers/ni_660x.c
index 405573e927cf..4ee9b260eab0 100644
--- a/drivers/staging/comedi/drivers/ni_660x.c
+++ b/drivers/staging/comedi/drivers/ni_660x.c
@@ -320,7 +320,6 @@ static inline void ni_660x_set_dma_channel(struct comedi_device *dev,
 	ni_660x_write(dev, chip, devpriv->dma_cfg[chip] |
 		      NI660X_DMA_CFG_RESET(mite_channel),
 		      NI660X_DMA_CFG);
-	mmiowb();
 }
 
 static inline void ni_660x_unset_dma_channel(struct comedi_device *dev,
@@ -333,7 +332,6 @@ static inline void ni_660x_unset_dma_channel(struct comedi_device *dev,
 	devpriv->dma_cfg[chip] &= ~NI660X_DMA_CFG_SEL_MASK(mite_channel);
 	devpriv->dma_cfg[chip] |= NI660X_DMA_CFG_SEL_NONE(mite_channel);
 	ni_660x_write(dev, chip, devpriv->dma_cfg[chip], NI660X_DMA_CFG);
-	mmiowb();
 }
 
 static int ni_660x_request_mite_channel(struct comedi_device *dev,
diff --git a/drivers/staging/comedi/drivers/ni_mio_common.c b/drivers/staging/comedi/drivers/ni_mio_common.c
index b04dad8c7092..668f2aa16baa 100644
--- a/drivers/staging/comedi/drivers/ni_mio_common.c
+++ b/drivers/staging/comedi/drivers/ni_mio_common.c
@@ -547,7 +547,6 @@ static inline void ni_set_bitfield(struct comedi_device *dev, int reg,
 			reg);
 		break;
 	}
-	mmiowb();
 	spin_unlock_irqrestore(&devpriv->soft_reg_copy_lock, flags);
 }
 
diff --git a/drivers/staging/comedi/drivers/ni_pcidio.c b/drivers/staging/comedi/drivers/ni_pcidio.c
index 4bdef87d5dd7..8f3864799c19 100644
--- a/drivers/staging/comedi/drivers/ni_pcidio.c
+++ b/drivers/staging/comedi/drivers/ni_pcidio.c
@@ -310,7 +310,6 @@ static int ni_pcidio_request_di_mite_channel(struct comedi_device *dev)
 	writeb(primary_DMAChannel_bits(devpriv->di_mite_chan->channel) |
 	       secondary_DMAChannel_bits(devpriv->di_mite_chan->channel),
 	       dev->mmio + DMA_LINE_CONTROL_GROUP1);
-	mmiowb();
 	spin_unlock_irqrestore(&devpriv->mite_channel_lock, flags);
 	return 0;
 }
@@ -327,7 +326,6 @@ static void ni_pcidio_release_di_mite_channel(struct comedi_device *dev)
 		writeb(primary_DMAChannel_bits(0) |
 		       secondary_DMAChannel_bits(0),
 		       dev->mmio + DMA_LINE_CONTROL_GROUP1);
-		mmiowb();
 	}
 	spin_unlock_irqrestore(&devpriv->mite_channel_lock, flags);
 }
diff --git a/drivers/staging/comedi/drivers/ni_tio.c b/drivers/staging/comedi/drivers/ni_tio.c
index 048cb35723ad..c1131a1622c0 100644
--- a/drivers/staging/comedi/drivers/ni_tio.c
+++ b/drivers/staging/comedi/drivers/ni_tio.c
@@ -234,7 +234,6 @@ static void ni_tio_set_bits_transient(struct ni_gpct *counter,
 		regs[reg] &= ~mask;
 		regs[reg] |= (value & mask);
 		ni_tio_write(counter, regs[reg] | transient, reg);
-		mmiowb();
 		spin_unlock_irqrestore(&counter_dev->regs_lock, flags);
 	}
 }
diff --git a/drivers/staging/comedi/drivers/s626.c b/drivers/staging/comedi/drivers/s626.c
index f5af6f4069dc..39049d3c56d7 100644
--- a/drivers/staging/comedi/drivers/s626.c
+++ b/drivers/staging/comedi/drivers/s626.c
@@ -108,7 +108,6 @@ static void s626_mc_enable(struct comedi_device *dev,
 {
 	unsigned int val = (cmd << 16) | cmd;
 
-	mmiowb();
 	writel(val, dev->mmio + reg);
 }
 
@@ -116,7 +115,6 @@ static void s626_mc_disable(struct comedi_device *dev,
 			    unsigned int cmd, unsigned int reg)
 {
 	writel(cmd << 16, dev->mmio + reg);
-	mmiowb();
 }
 
 static bool s626_mc_test(struct comedi_device *dev,