[PATCH 6/6] spi/pl022: add support for pm_runtime autosuspend

[Viresh Kumar]

On 11/9/2011 4:09 PM, Linus WALLEIJ wrote:
> From: Chris Blair <chris.blair at stericsson.com>
> 
> Adds support for configuring the spi bus to use autosuspend for
> runtime power management. This can reduce the latency in starting an
> spi transfer by not suspending the device immediately following
> completion of a transfer. If another transfer then takes place before
> the autosuspend timeout, the call to resume the device can return
> immediately rather than needing to risk sleeping in order to resume
> the device.
> 
> Signed-off-by: Chris Blair <chris.blair at stericsson.com>
> Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
> ---
>  drivers/spi/spi-pl022.c    |   20 ++++++++++++++++++--
>  include/linux/amba/pl022.h |    4 ++++
>  2 files changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c
> index 2e3522d..d3d6521 100644
> --- a/drivers/spi/spi-pl022.c
> +++ b/drivers/spi/spi-pl022.c
> @@ -1515,7 +1515,13 @@ static void pump_messages(struct work_struct *work)
>  			/* nothing more to do - disable spi/ssp and power off */
>  			writew((readw(SSP_CR1(pl022->virtbase)) &
>  				(~SSP_CR1_MASK_SSE)), SSP_CR1(pl022->virtbase));
> -			pm_runtime_put(&pl022->adev->dev);
> +
> +			if (pl022->master_info->autosuspend_delay > 0) {
> +				pm_runtime_mark_last_busy(&pl022->adev->dev);
> +				pm_runtime_put_autosuspend(&pl022->adev->dev);
> +			} else {
> +				pm_runtime_put(&pl022->adev->dev);
> +			}
>  		}
>  		pl022->busy = false;
>  		spin_unlock_irqrestore(&pl022->queue_lock, flags);
> @@ -2245,7 +2251,17 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id)
>  	dev_dbg(dev, "probe succeeded\n");
>  
>  	/* let runtime pm put suspend */
> -	pm_runtime_put(dev);
> +	if (platform_info->autosuspend_delay > 0) {
> +		dev_info(&adev->dev,
> +			"will use autosuspend for runtime pm, delay %dms\n",
> +			platform_info->autosuspend_delay);
> +		pm_runtime_set_autosuspend_delay(dev,
> +			platform_info->autosuspend_delay);
> +		pm_runtime_use_autosuspend(dev);
> +		pm_runtime_put_autosuspend(dev);
> +	} else {
> +		pm_runtime_put(dev);
> +	}
>  	return 0;
>  
>   err_spi_register:
> diff --git a/include/linux/amba/pl022.h b/include/linux/amba/pl022.h
> index 4ce98f5..572f637 100644
> --- a/include/linux/amba/pl022.h
> +++ b/include/linux/amba/pl022.h
> @@ -238,6 +238,9 @@ struct dma_chan;
>   * @enable_dma: if true enables DMA driven transfers.
>   * @dma_rx_param: parameter to locate an RX DMA channel.
>   * @dma_tx_param: parameter to locate a TX DMA channel.
> + * @autosuspend_delay: delay in ms following transfer completion before the
> + *     runtime power management system suspends the device. A setting of 0
> + *     indicates no delay and the device will be suspended immediately.
>   */
>  struct pl022_ssp_controller {
>  	u16 bus_id;
> @@ -246,6 +249,7 @@ struct pl022_ssp_controller {
>  	bool (*dma_filter)(struct dma_chan *chan, void *filter_param);
>  	void *dma_rx_param;
>  	void *dma_tx_param;
> +	int autosuspend_delay;
>  };
>  
>  /**

Reviewed-by: Viresh Kumar <viresh.kumar at st.com>

-- 
viresh