[PATCHv8 04/18] I2C: OMAP: I2C register restore only if context is lost
Kevin Hilman
khilman at ti.com
Wed Apr 18 10:08:40 EDT 2012
"Datta, Shubhrajyoti" <shubhrajyoti at ti.com> writes:
> Hi Kevin,
>
>> Hi Kevin,
>> Thanks for your review,
>>
>> On Tue, Apr 17, 2012 at 7:15 PM, Kevin Hilman <khilman at ti.com> wrote:
>>> Shubhrajyoti D <shubhrajyoti at ti.com> writes:
>>>
>>>> Currently i2c register restore is done always.
>>>> Adding conditional restore.
>>>> The i2c register restore is done only if the context is lost.
>>>
>>> OK, minor comment below.
>
> Thanks for the suggestion of the error case restore.
> Updated the patch. Also added Tony's ack for the plat part.
>
>
> From 1ca222f6f50868e07d9a46575e73dd66fd2d542e Mon Sep 17 00:00:00 2001
> From: Shubhrajyoti D <shubhrajyoti at ti.com>
> Date: Tue, 17 Jan 2012 16:13:03 +0530
> Subject: [PATCH] I2C: OMAP: I2C register restore only if context is lost
>
> Currently i2c register restore is done always.
> Adding conditional restore.
> The i2c register restore is done only if the context is lost
> or in case of error to be on the safe side.
> Also remove the definition of SYSS_RESETDONE_MASK and use the
> one in omap_hwmod.h.
>
> Cc: Kevin Hilman <khilman at ti.com>
> [For the arch/arm/plat-omap/i2c.c part]
> Acked-by: Tony Lindgren <tony at atomide.com>
> Signed-off-by: Shubhrajyoti D <shubhrajyoti at ti.com>
> ---
> arch/arm/plat-omap/i2c.c | 3 ++
> drivers/i2c/busses/i2c-omap.c | 53 +++++++++++++++++++++++++++--------------
> include/linux/i2c-omap.h | 1 +
> 3 files changed, 39 insertions(+), 18 deletions(-)
>
> diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
> index db071bc..4ccab07 100644
> --- a/arch/arm/plat-omap/i2c.c
> +++ b/arch/arm/plat-omap/i2c.c
> @@ -179,6 +179,9 @@ static inline int omap2_i2c_add_bus(int bus_id)
> */
> if (cpu_is_omap34xx())
> pdata->set_mpu_wkup_lat = omap_pm_set_max_mpu_wakeup_lat_compat;
> +
> + pdata->get_context_loss_count = omap_pm_get_dev_context_loss_count;
> +
> 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 a882558..76cf066 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -43,6 +43,7 @@
> #include <linux/slab.h>
> #include <linux/i2c-omap.h>
> #include <linux/pm_runtime.h>
> +#include <plat/omap_device.h>
>
> /* I2C controller revisions */
> #define OMAP_I2C_OMAP1_REV_2 0x20
> @@ -157,9 +158,6 @@ enum {
> #define OMAP_I2C_SYSTEST_SDA_I (1 << 1) /* SDA line sense in */
> #define OMAP_I2C_SYSTEST_SDA_O (1 << 0) /* SDA line drive out */
>
> -/* OCP_SYSSTATUS bit definitions */
> -#define SYSS_RESETDONE_MASK (1 << 0)
> -
Unrelated to this patch.
> /* OCP_SYSCONFIG bit definitions */
> #define SYSC_CLOCKACTIVITY_MASK (0x3 << 8)
> #define SYSC_SIDLEMODE_MASK (0x3 << 3)
> @@ -184,6 +182,7 @@ struct omap_i2c_dev {
> u32 latency; /* maximum mpu wkup latency */
> void (*set_mpu_wkup_lat)(struct device *dev,
> long latency);
> + int (*get_context_loss_count)(struct device *dev);
> u32 speed; /* Speed of bus in kHz */
> u32 dtrev; /* extra revision from DT */
> u32 flags;
> @@ -206,6 +205,7 @@ struct omap_i2c_dev {
> u16 syscstate;
> u16 westate;
> u16 errata;
> + int dev_lost_count;
> };
>
> static const u8 reg_map_ip_v1[] = {
> @@ -1025,6 +1025,7 @@ omap_i2c_probe(struct platform_device *pdev)
> dev->speed = pdata->clkrate;
> dev->flags = pdata->flags;
> dev->set_mpu_wkup_lat = pdata->set_mpu_wkup_lat;
> + dev->get_context_loss_count = pdata->get_context_loss_count;
> dev->dtrev = pdata->rev;
> }
>
> @@ -1151,12 +1152,32 @@ omap_i2c_remove(struct platform_device *pdev)
> }
>
> #ifdef CONFIG_PM_RUNTIME
> +static void omap_i2c_restore(struct omap_i2c_dev *dev)
> +{
> + omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, 0);
> + omap_i2c_write_reg(dev, OMAP_I2C_PSC_REG, dev->pscstate);
> + omap_i2c_write_reg(dev, OMAP_I2C_SCLL_REG, dev->scllstate);
> + omap_i2c_write_reg(dev, OMAP_I2C_SCLH_REG, dev->sclhstate);
> + omap_i2c_write_reg(dev, OMAP_I2C_BUF_REG, dev->bufstate);
> + omap_i2c_write_reg(dev, OMAP_I2C_WE_REG, dev->westate);
> + omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
> + /*
> + * Don't write to this register if the IE state is 0 as it can
> + * cause deadlock.
> + */
> + if (dev->iestate)
> + omap_i2c_write_reg(dev, OMAP_I2C_IE_REG, dev->iestate);
> +
> +}
> static int omap_i2c_runtime_suspend(struct device *dev)
> {
> struct platform_device *pdev = to_platform_device(dev);
> struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
> u16 iv;
>
> + if (_dev->get_context_loss_count)
> + _dev->dev_lost_count = _dev->get_context_loss_count(dev);
> +
> _dev->iestate = omap_i2c_read_reg(_dev, OMAP_I2C_IE_REG);
> if (_dev->dtrev == OMAP_I2C_IP_VERSION_2)
> omap_i2c_write_reg(_dev, OMAP_I2C_IP_V2_IRQENABLE_CLR, 1);
> @@ -1179,24 +1200,20 @@ static int omap_i2c_runtime_resume(struct device *dev)
> {
> struct platform_device *pdev = to_platform_device(dev);
> struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
> + int loss_cnt;
>
> - if (_dev->flags & OMAP_I2C_FLAG_RESET_REGS_POSTIDLE) {
> - omap_i2c_write_reg(_dev, OMAP_I2C_CON_REG, 0);
> - omap_i2c_write_reg(_dev, OMAP_I2C_PSC_REG, _dev->pscstate);
> - omap_i2c_write_reg(_dev, OMAP_I2C_SCLL_REG, _dev->scllstate);
> - omap_i2c_write_reg(_dev, OMAP_I2C_SCLH_REG, _dev->sclhstate);
> - omap_i2c_write_reg(_dev, OMAP_I2C_BUF_REG, _dev->bufstate);
> - omap_i2c_write_reg(_dev, OMAP_I2C_SYSC_REG, _dev->syscstate);
> - omap_i2c_write_reg(_dev, OMAP_I2C_WE_REG, _dev->westate);
> - omap_i2c_write_reg(_dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
> + if (_dev->get_context_loss_count) {
> + loss_cnt = _dev->get_context_loss_count(dev);
> + if (loss_cnt < 0) {
> + omap_i2c_restore(_dev);
> + return 0;
> + }
> + if (_dev->dev_lost_count == loss_cnt && _dev->dev_lost_count)
> + return 0;
Again, why does it matter if _dev->dev_lost_count != 0?
IMO, this is still more confusing than it needs to be. What is wrong
with
if (_dev->flags & OMAP_I2C_FLAG_RESET_REGS_POSTIDLE)
return 0;
/* read current loss_cnt */
if (_dev->dev_lost_count != loss_cnt)
omap_i2c_restore(_dev);
return 0;
Kevin
>
> - /*
> - * Don't write to this register if the IE state is 0 as it can
> - * cause deadlock.
> - */
> - if (_dev->iestate)
> - omap_i2c_write_reg(_dev, OMAP_I2C_IE_REG, _dev->iestate);
> + if (_dev->flags & OMAP_I2C_FLAG_RESET_REGS_POSTIDLE)
> + omap_i2c_restore(_dev);
>
> return 0;
> }
> diff --git a/include/linux/i2c-omap.h b/include/linux/i2c-omap.h
> index 92a0dc7..c76cbc0 100644
> --- a/include/linux/i2c-omap.h
> +++ b/include/linux/i2c-omap.h
> @@ -35,6 +35,7 @@ struct omap_i2c_bus_platform_data {
> u32 rev;
> u32 flags;
> void (*set_mpu_wkup_lat)(struct device *dev, long set);
> + int (*get_context_loss_count)(struct device *dev);
> };
>
> #endif
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