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SubjectRe: [PATCH v4 1/2] i2c: davinci: Add PM Runtime Support
Hi,

On 12 September 2017 at 04:11, Franklin S Cooper Jr <fcooper@ti.com> wrote:
> 66AK2G has I2C instances that are not apart of the ALWAYS_ON power domain
> unlike other Keystone 2 SoCs and OMAPL138. Therefore, pm_runtime
> is required to insure the power domain used by the specific I2C instance is
> properly turned on along with its functional clock.
>
> Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
> ---
> Version 4 changes:
> Fix wording on error message
> Fix additional error path
>
> Version 3 changes:
> Remove several statements that set clk to NULL
> Fix error path
>
> drivers/i2c/busses/i2c-davinci.c | 67 +++++++++++++++++++++++++++++++++-------
> 1 file changed, 55 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
> index b8c4353..a2d9f7c 100644
> --- a/drivers/i2c/busses/i2c-davinci.c
> +++ b/drivers/i2c/busses/i2c-davinci.c
> @@ -36,6 +36,7 @@
> #include <linux/gpio.h>
> #include <linux/of_device.h>
> #include <linux/platform_data/i2c-davinci.h>
> +#include <linux/pm_runtime.h>
>
> /* ----- global defines ----------------------------------------------- */
>
> @@ -122,6 +123,9 @@
> /* set the SDA GPIO low */
> #define DAVINCI_I2C_DCLR_PDCLR1 BIT(1)
>
> +/* timeout for pm runtime autosuspend */
> +#define DAVINCI_I2C_PM_TIMEOUT 1000 /* ms */
> +
> struct davinci_i2c_dev {
> struct device *dev;
> void __iomem *base;
> @@ -541,10 +545,17 @@ i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>
> dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
>
> + ret = pm_runtime_get_sync(dev->dev);
> + if (ret < 0) {
> + dev_err(dev->dev, "Failed to runtime_get device: %d\n", ret);
> + pm_runtime_put_noidle(dev->dev);
> + return ret;
> + }
> +
> ret = i2c_davinci_wait_bus_not_busy(dev);
> if (ret < 0) {
> dev_warn(dev->dev, "timeout waiting for bus ready\n");
> - return ret;
> + goto out;
> }
>
> for (i = 0; i < num; i++) {
> @@ -552,14 +563,19 @@ i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> dev_dbg(dev->dev, "%s [%d/%d] ret: %d\n", __func__, i + 1, num,
> ret);
> if (ret < 0)
> - return ret;
> + goto out;
> }
>
> + ret = num;
> #ifdef CONFIG_CPU_FREQ
> complete(&dev->xfr_complete);
> #endif
>
> - return num;
> +out:
> + pm_runtime_mark_last_busy(dev->dev);
> + pm_runtime_put_autosuspend(dev->dev);
> +
> + return ret;
> }
>
> static u32 i2c_davinci_func(struct i2c_adapter *adap)
> @@ -599,6 +615,9 @@ static irqreturn_t i2c_davinci_isr(int this_irq, void *dev_id)
> int count = 0;
> u16 w;
>
> + if (pm_runtime_suspended(dev->dev))
> + return IRQ_NONE;
> +
> while ((stat = davinci_i2c_read_reg(dev, DAVINCI_I2C_IVR_REG))) {
> dev_dbg(dev->dev, "%s: stat=0x%x\n", __func__, stat);
> if (count++ == 100) {
> @@ -802,13 +821,24 @@ static int davinci_i2c_probe(struct platform_device *pdev)
> dev->clk = devm_clk_get(&pdev->dev, NULL);
> if (IS_ERR(dev->clk))
> return PTR_ERR(dev->clk);
> - clk_prepare_enable(dev->clk);

You removed clk enable here, I think it can not work if we did not
open CONFIG_PM macro. I think you should keep clk enable here, and set
rpm active by pm_runtime_set_active() before issuing
pm_runtime_enable().

>
> mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> dev->base = devm_ioremap_resource(&pdev->dev, mem);
> if (IS_ERR(dev->base)) {
> - r = PTR_ERR(dev->base);
> - goto err_unuse_clocks;
> + return PTR_ERR(dev->base);
> + }
> +
> + pm_runtime_set_autosuspend_delay(dev->dev,
> + DAVINCI_I2C_PM_TIMEOUT);
> + pm_runtime_use_autosuspend(dev->dev);
> +
> + pm_runtime_enable(dev->dev);
> +
> + r = pm_runtime_get_sync(dev->dev);
> + if (r < 0) {
> + dev_err(dev->dev, "failed to runtime_get device: %d\n", r);
> + pm_runtime_put_noidle(dev->dev);
> + return r;
> }
>
> i2c_davinci_init(dev);
> @@ -849,27 +879,40 @@ static int davinci_i2c_probe(struct platform_device *pdev)
> if (r)
> goto err_unuse_clocks;
>
> + pm_runtime_mark_last_busy(dev->dev);
> + pm_runtime_put_autosuspend(dev->dev);
> +
> return 0;
>
> err_unuse_clocks:
> - clk_disable_unprepare(dev->clk);
> - dev->clk = NULL;
> + pm_runtime_dont_use_autosuspend(dev->dev);
> + pm_runtime_put_sync(dev->dev);
> + pm_runtime_disable(dev->dev);
> +
> return r;
> }
>
> static int davinci_i2c_remove(struct platform_device *pdev)
> {
> struct davinci_i2c_dev *dev = platform_get_drvdata(pdev);
> + int ret;
>
> i2c_davinci_cpufreq_deregister(dev);
>
> i2c_del_adapter(&dev->adapter);
>
> - clk_disable_unprepare(dev->clk);
> - dev->clk = NULL;
> + ret = pm_runtime_get_sync(&pdev->dev);
> + if (ret < 0) {
> + pm_runtime_put_noidle(&pdev->dev);
> + return ret;
> + }
>
> davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, 0);
>
> + pm_runtime_dont_use_autosuspend(dev->dev);
> + pm_runtime_put_sync(dev->dev);
> + pm_runtime_disable(dev->dev);
> +
> return 0;
> }
>
> @@ -880,7 +923,6 @@ static int davinci_i2c_suspend(struct device *dev)
>
> /* put I2C into reset */
> davinci_i2c_reset_ctrl(i2c_dev, 0);
> - clk_disable_unprepare(i2c_dev->clk);
>
> return 0;
> }
> @@ -889,7 +931,6 @@ static int davinci_i2c_resume(struct device *dev)
> {
> struct davinci_i2c_dev *i2c_dev = dev_get_drvdata(dev);
>
> - clk_prepare_enable(i2c_dev->clk);
> /* take I2C out of reset */
> davinci_i2c_reset_ctrl(i2c_dev, 1);
>
> @@ -899,6 +940,8 @@ static int davinci_i2c_resume(struct device *dev)
> static const struct dev_pm_ops davinci_i2c_pm = {
> .suspend = davinci_i2c_suspend,
> .resume = davinci_i2c_resume,
> + SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> + pm_runtime_force_resume)
> };
>
> #define davinci_i2c_pm_ops (&davinci_i2c_pm)
> --
> 2.9.4.dirty
>



--
Baolin.wang
Best Regards

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