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

Lee Jones
2017-03-23T13:42:52Z

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
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