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[PATCH v2 5/9] mfd: t7l66xb: make use of raw_spinlock variants

Started byJulia Cartwright <julia@ni.com>
First post2017-03-22 00:40 +0100
Last post2017-03-23 14:50 +0100
Articles 2 — 2 participants

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  [PATCH v2 5/9] mfd: t7l66xb: make use of raw_spinlock variants Julia Cartwright <julia@ni.com> - 2017-03-22 00:40 +0100
    Re: [PATCH v2 5/9] mfd: t7l66xb: make use of raw_spinlock variants Lee Jones <lee.jones@linaro.org> - 2017-03-23 14:50 +0100

#1606079 — [PATCH v2 5/9] mfd: t7l66xb: make use of raw_spinlock variants

FromJulia Cartwright <julia@ni.com>
Date2017-03-22 00:40 +0100
Subject[PATCH v2 5/9] mfd: t7l66xb: make use of raw_spinlock variants
Message-ID<tnBxE-1Vz-13@gated-at.bofh.it>
The t7l66xb mfd driver currently implements an irq_chip for handling
interrupts; due to how irq_chip handling is done, it's necessary for the
irq_chip methods to be invoked from hardirq context, even on a a
real-time kernel.  Because the spinlock_t type becomes a "sleeping"
spinlock w/ RT kernels, it is not suitable to be used with irq_chips.

A quick audit of the operations under the lock reveal that they do only
minimal, bounded work, and are therefore safe to do under a raw spinlock.

Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Julia Cartwright <julia@ni.com>
---
v1 -> v2:
  - No functional change.  Added Lee's ack.

 drivers/mfd/t7l66xb.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/mfd/t7l66xb.c b/drivers/mfd/t7l66xb.c
index 94bd89cb1f06..22c811396edc 100644
--- a/drivers/mfd/t7l66xb.c
+++ b/drivers/mfd/t7l66xb.c
@@ -69,7 +69,7 @@ static const struct resource t7l66xb_mmc_resources[] = {
 struct t7l66xb {
 	void __iomem		*scr;
 	/* Lock to protect registers requiring read/modify/write ops. */
-	spinlock_t		lock;
+	raw_spinlock_t		lock;
 
 	struct resource		rscr;
 	struct clk		*clk48m;
@@ -89,13 +89,13 @@ static int t7l66xb_mmc_enable(struct platform_device *mmc)
 
 	clk_prepare_enable(t7l66xb->clk32k);
 
-	spin_lock_irqsave(&t7l66xb->lock, flags);
+	raw_spin_lock_irqsave(&t7l66xb->lock, flags);
 
 	dev_ctl = tmio_ioread8(t7l66xb->scr + SCR_DEV_CTL);
 	dev_ctl |= SCR_DEV_CTL_MMC;
 	tmio_iowrite8(dev_ctl, t7l66xb->scr + SCR_DEV_CTL);
 
-	spin_unlock_irqrestore(&t7l66xb->lock, flags);
+	raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);
 
 	tmio_core_mmc_enable(t7l66xb->scr + 0x200, 0,
 		t7l66xb_mmc_resources[0].start & 0xfffe);
@@ -110,13 +110,13 @@ static int t7l66xb_mmc_disable(struct platform_device *mmc)
 	unsigned long flags;
 	u8 dev_ctl;
 
-	spin_lock_irqsave(&t7l66xb->lock, flags);
+	raw_spin_lock_irqsave(&t7l66xb->lock, flags);
 
 	dev_ctl = tmio_ioread8(t7l66xb->scr + SCR_DEV_CTL);
 	dev_ctl &= ~SCR_DEV_CTL_MMC;
 	tmio_iowrite8(dev_ctl, t7l66xb->scr + SCR_DEV_CTL);
 
-	spin_unlock_irqrestore(&t7l66xb->lock, flags);
+	raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);
 
 	clk_disable_unprepare(t7l66xb->clk32k);
 
@@ -206,11 +206,11 @@ static void t7l66xb_irq_mask(struct irq_data *data)
 	unsigned long			flags;
 	u8 imr;
 
-	spin_lock_irqsave(&t7l66xb->lock, flags);
+	raw_spin_lock_irqsave(&t7l66xb->lock, flags);
 	imr = tmio_ioread8(t7l66xb->scr + SCR_IMR);
 	imr |= 1 << (data->irq - t7l66xb->irq_base);
 	tmio_iowrite8(imr, t7l66xb->scr + SCR_IMR);
-	spin_unlock_irqrestore(&t7l66xb->lock, flags);
+	raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);
 }
 
 static void t7l66xb_irq_unmask(struct irq_data *data)
@@ -219,11 +219,11 @@ static void t7l66xb_irq_unmask(struct irq_data *data)
 	unsigned long flags;
 	u8 imr;
 
-	spin_lock_irqsave(&t7l66xb->lock, flags);
+	raw_spin_lock_irqsave(&t7l66xb->lock, flags);
 	imr = tmio_ioread8(t7l66xb->scr + SCR_IMR);
 	imr &= ~(1 << (data->irq - t7l66xb->irq_base));
 	tmio_iowrite8(imr, t7l66xb->scr + SCR_IMR);
-	spin_unlock_irqrestore(&t7l66xb->lock, flags);
+	raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);
 }
 
 static struct irq_chip t7l66xb_chip = {
@@ -321,7 +321,7 @@ static int t7l66xb_probe(struct platform_device *dev)
 	if (!t7l66xb)
 		return -ENOMEM;
 
-	spin_lock_init(&t7l66xb->lock);
+	raw_spin_lock_init(&t7l66xb->lock);
 
 	platform_set_drvdata(dev, t7l66xb);
 
-- 
2.12.0

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#1607507

FromLee Jones <lee.jones@linaro.org>
Date2017-03-23 14:50 +0100
Message-ID<tobhM-2SB-13@gated-at.bofh.it>
In reply to#1606079
On Tue, 21 Mar 2017, Julia Cartwright wrote:

> The t7l66xb mfd driver currently implements an irq_chip for handling
> interrupts; due to how irq_chip handling is done, it's necessary for the
> irq_chip methods to be invoked from hardirq context, even on a a
> real-time kernel.  Because the spinlock_t type becomes a "sleeping"
> spinlock w/ RT kernels, it is not suitable to be used with irq_chips.
> 
> A quick audit of the operations under the lock reveal that they do only
> minimal, bounded work, and are therefore safe to do under a raw spinlock.
> 
> Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>
> Signed-off-by: Julia Cartwright <julia@ni.com>
> ---
> v1 -> v2:
>   - No functional change.  Added Lee's ack.
> 
>  drivers/mfd/t7l66xb.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)

Applied, thanks.

> diff --git a/drivers/mfd/t7l66xb.c b/drivers/mfd/t7l66xb.c
> index 94bd89cb1f06..22c811396edc 100644
> --- a/drivers/mfd/t7l66xb.c
> +++ b/drivers/mfd/t7l66xb.c
> @@ -69,7 +69,7 @@ static const struct resource t7l66xb_mmc_resources[] = {
>  struct t7l66xb {
>  	void __iomem		*scr;
>  	/* Lock to protect registers requiring read/modify/write ops. */
> -	spinlock_t		lock;
> +	raw_spinlock_t		lock;
>  
>  	struct resource		rscr;
>  	struct clk		*clk48m;
> @@ -89,13 +89,13 @@ static int t7l66xb_mmc_enable(struct platform_device *mmc)
>  
>  	clk_prepare_enable(t7l66xb->clk32k);
>  
> -	spin_lock_irqsave(&t7l66xb->lock, flags);
> +	raw_spin_lock_irqsave(&t7l66xb->lock, flags);
>  
>  	dev_ctl = tmio_ioread8(t7l66xb->scr + SCR_DEV_CTL);
>  	dev_ctl |= SCR_DEV_CTL_MMC;
>  	tmio_iowrite8(dev_ctl, t7l66xb->scr + SCR_DEV_CTL);
>  
> -	spin_unlock_irqrestore(&t7l66xb->lock, flags);
> +	raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);
>  
>  	tmio_core_mmc_enable(t7l66xb->scr + 0x200, 0,
>  		t7l66xb_mmc_resources[0].start & 0xfffe);
> @@ -110,13 +110,13 @@ static int t7l66xb_mmc_disable(struct platform_device *mmc)
>  	unsigned long flags;
>  	u8 dev_ctl;
>  
> -	spin_lock_irqsave(&t7l66xb->lock, flags);
> +	raw_spin_lock_irqsave(&t7l66xb->lock, flags);
>  
>  	dev_ctl = tmio_ioread8(t7l66xb->scr + SCR_DEV_CTL);
>  	dev_ctl &= ~SCR_DEV_CTL_MMC;
>  	tmio_iowrite8(dev_ctl, t7l66xb->scr + SCR_DEV_CTL);
>  
> -	spin_unlock_irqrestore(&t7l66xb->lock, flags);
> +	raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);
>  
>  	clk_disable_unprepare(t7l66xb->clk32k);
>  
> @@ -206,11 +206,11 @@ static void t7l66xb_irq_mask(struct irq_data *data)
>  	unsigned long			flags;
>  	u8 imr;
>  
> -	spin_lock_irqsave(&t7l66xb->lock, flags);
> +	raw_spin_lock_irqsave(&t7l66xb->lock, flags);
>  	imr = tmio_ioread8(t7l66xb->scr + SCR_IMR);
>  	imr |= 1 << (data->irq - t7l66xb->irq_base);
>  	tmio_iowrite8(imr, t7l66xb->scr + SCR_IMR);
> -	spin_unlock_irqrestore(&t7l66xb->lock, flags);
> +	raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);
>  }
>  
>  static void t7l66xb_irq_unmask(struct irq_data *data)
> @@ -219,11 +219,11 @@ static void t7l66xb_irq_unmask(struct irq_data *data)
>  	unsigned long flags;
>  	u8 imr;
>  
> -	spin_lock_irqsave(&t7l66xb->lock, flags);
> +	raw_spin_lock_irqsave(&t7l66xb->lock, flags);
>  	imr = tmio_ioread8(t7l66xb->scr + SCR_IMR);
>  	imr &= ~(1 << (data->irq - t7l66xb->irq_base));
>  	tmio_iowrite8(imr, t7l66xb->scr + SCR_IMR);
> -	spin_unlock_irqrestore(&t7l66xb->lock, flags);
> +	raw_spin_unlock_irqrestore(&t7l66xb->lock, flags);
>  }
>  
>  static struct irq_chip t7l66xb_chip = {
> @@ -321,7 +321,7 @@ static int t7l66xb_probe(struct platform_device *dev)
>  	if (!t7l66xb)
>  		return -ENOMEM;
>  
> -	spin_lock_init(&t7l66xb->lock);
> +	raw_spin_lock_init(&t7l66xb->lock);
>  
>  	platform_set_drvdata(dev, t7l66xb);
>  

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

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