Re: [PATCH] Revert "ARM: OMAP: convert I2C driver to PM QoS for MPU latency constraints"

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On Tue, Nov 6, 2012 at 5:31 PM, Paul Walmsley <paul@xxxxxxxxx> wrote:
>
> This reverts commit 3db11feffc1ad2ab9dea27789e6b5b3032827adc.
> This commit causes I2C timeouts to appear on several OMAP3430/3530-based
> boards:
>
>   http://marc.info/?l=linux-arm-kernel&m=135071372426971&w=2
>   http://marc.info/?l=linux-arm-kernel&m=135067558415214&w=2
>   http://marc.info/?l=linux-arm-kernel&m=135216013608196&w=2
>
> and appears to have been sent for merging before one of its prerequisites
> was merged:
>
>   http://marc.info/?l=linux-arm-kernel&m=135219411617621&w=2

Indeed.

Acked-by: Jean Pihet <j-pihet@xxxxxx>

>
> Signed-off-by: Paul Walmsley <paul@xxxxxxxxx>
> Cc: Jean Pihet <jean.pihet@xxxxxxxxxxxxxx>
> Cc: Kevin Hilman <khilman@xxxxxx>
> Cc: Aaro Koskinen <aaro.koskinen@xxxxxx>
> Cc: Felipe Balbi <balbi@xxxxxx>
> ---
>
> Intended for 3.7-rc.
>
>  arch/arm/plat-omap/i2c.c      |   21 +++++++++++++++++++++
>  drivers/i2c/busses/i2c-omap.c |   32 ++++++++++++++------------------
>  include/linux/i2c-omap.h      |    1 +
>  3 files changed, 36 insertions(+), 18 deletions(-)
>
> diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
> index a5683a8..6013831 100644
> --- a/arch/arm/plat-omap/i2c.c
> +++ b/arch/arm/plat-omap/i2c.c
> @@ -26,12 +26,14 @@
>  #include <linux/kernel.h>
>  #include <linux/platform_device.h>
>  #include <linux/i2c.h>
> +#include <linux/i2c-omap.h>
>  #include <linux/slab.h>
>  #include <linux/err.h>
>  #include <linux/clk.h>
>
>  #include <mach/irqs.h>
>  #include <plat/i2c.h>
> +#include <plat/omap-pm.h>
>  #include <plat/omap_device.h>
>
>  #define OMAP_I2C_SIZE          0x3f
> @@ -127,6 +129,16 @@ static inline int omap1_i2c_add_bus(int bus_id)
>
>
>  #ifdef CONFIG_ARCH_OMAP2PLUS
> +/*
> + * XXX This function is a temporary compatibility wrapper - only
> + * needed until the I2C driver can be converted to call
> + * omap_pm_set_max_dev_wakeup_lat() and handle a return code.
> + */
> +static void omap_pm_set_max_mpu_wakeup_lat_compat(struct device *dev, long t)
> +{
> +       omap_pm_set_max_mpu_wakeup_lat(dev, t);
> +}
> +
>  static inline int omap2_i2c_add_bus(int bus_id)
>  {
>         int l;
> @@ -158,6 +170,15 @@ static inline int omap2_i2c_add_bus(int bus_id)
>         dev_attr = (struct omap_i2c_dev_attr *)oh->dev_attr;
>         pdata->flags = dev_attr->flags;
>
> +       /*
> +        * When waiting for completion of a i2c transfer, we need to
> +        * set a wake up latency constraint for the MPU. This is to
> +        * ensure quick enough wakeup from idle, when transfer
> +        * completes.
> +        * Only omap3 has support for constraints
> +        */
> +       if (cpu_is_omap34xx())
> +               pdata->set_mpu_wkup_lat = omap_pm_set_max_mpu_wakeup_lat_compat;
>         pdev = omap_device_build(name, bus_id, oh, pdata,
>                         sizeof(struct omap_i2c_bus_platform_data),
>                         NULL, 0, 0);
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index db31eae..0b02543 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -43,7 +43,6 @@
>  #include <linux/slab.h>
>  #include <linux/i2c-omap.h>
>  #include <linux/pm_runtime.h>
> -#include <linux/pm_qos.h>
>
>  /* I2C controller revisions */
>  #define OMAP_I2C_OMAP1_REV_2           0x20
> @@ -187,8 +186,9 @@ struct omap_i2c_dev {
>         int                     reg_shift;      /* bit shift for I2C register addresses */
>         struct completion       cmd_complete;
>         struct resource         *ioarea;
> -       u32                     latency;        /* maximum MPU wkup latency */
> -       struct pm_qos_request   pm_qos_request;
> +       u32                     latency;        /* maximum mpu wkup latency */
> +       void                    (*set_mpu_wkup_lat)(struct device *dev,
> +                                                   long latency);
>         u32                     speed;          /* Speed of bus in kHz */
>         u32                     dtrev;          /* extra revision from DT */
>         u32                     flags;
> @@ -494,7 +494,9 @@ static void omap_i2c_resize_fifo(struct omap_i2c_dev *dev, u8 size, bool is_rx)
>                 dev->b_hw = 1; /* Enable hardware fixes */
>
>         /* calculate wakeup latency constraint for MPU */
> -       dev->latency = (1000000 * dev->threshold) / (1000 * dev->speed / 8);
> +       if (dev->set_mpu_wkup_lat != NULL)
> +               dev->latency = (1000000 * dev->threshold) /
> +                       (1000 * dev->speed / 8);
>  }
>
>  /*
> @@ -629,16 +631,8 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>         if (r < 0)
>                 goto out;
>
> -       /*
> -        * When waiting for completion of a i2c transfer, we need to
> -        * set a wake up latency constraint for the MPU. This is to
> -        * ensure quick enough wakeup from idle, when transfer
> -        * completes.
> -        */
> -       if (dev->latency)
> -               pm_qos_add_request(&dev->pm_qos_request,
> -                                  PM_QOS_CPU_DMA_LATENCY,
> -                                  dev->latency);
> +       if (dev->set_mpu_wkup_lat != NULL)
> +               dev->set_mpu_wkup_lat(dev->dev, dev->latency);
>
>         for (i = 0; i < num; i++) {
>                 r = omap_i2c_xfer_msg(adap, &msgs[i], (i == (num - 1)));
> @@ -646,8 +640,8 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>                         break;
>         }
>
> -       if (dev->latency)
> -               pm_qos_remove_request(&dev->pm_qos_request);
> +       if (dev->set_mpu_wkup_lat != NULL)
> +               dev->set_mpu_wkup_lat(dev->dev, -1);
>
>         if (r == 0)
>                 r = num;
> @@ -1104,6 +1098,7 @@ omap_i2c_probe(struct platform_device *pdev)
>         } else if (pdata != NULL) {
>                 dev->speed = pdata->clkrate;
>                 dev->flags = pdata->flags;
> +               dev->set_mpu_wkup_lat = pdata->set_mpu_wkup_lat;
>                 dev->dtrev = pdata->rev;
>         }
>
> @@ -1159,8 +1154,9 @@ omap_i2c_probe(struct platform_device *pdev)
>                         dev->b_hw = 1; /* Enable hardware fixes */
>
>                 /* calculate wakeup latency constraint for MPU */
> -               dev->latency = (1000000 * dev->fifo_size) /
> -                              (1000 * dev->speed / 8);
> +               if (dev->set_mpu_wkup_lat != NULL)
> +                       dev->latency = (1000000 * dev->fifo_size) /
> +                                      (1000 * dev->speed / 8);
>         }
>
>         /* reset ASAP, clearing any IRQs */
> diff --git a/include/linux/i2c-omap.h b/include/linux/i2c-omap.h
> index df804ba..92a0dc7 100644
> --- a/include/linux/i2c-omap.h
> +++ b/include/linux/i2c-omap.h
> @@ -34,6 +34,7 @@ struct omap_i2c_bus_platform_data {
>         u32             clkrate;
>         u32             rev;
>         u32             flags;
> +       void            (*set_mpu_wkup_lat)(struct device *dev, long set);
>  };
>
>  #endif
> --
> 1.7.10.4
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