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Message-ID: <1BAFE6F6C881BF42822005164F1491C33EC28748@DBDE04.ent.ti.com>
Date: Wed, 5 Jun 2013 09:04:31 +0000
From: "Hebbar, Gururaja" <gururaja.hebbar@...com>
To: "Strashko, Grygorii" <grygorii.strashko@...com>
CC: "khilman@...aro.org" <khilman@...aro.org>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
"linus.walleij@...aro.org" <linus.walleij@...aro.org>,
"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
"davinci-linux-open-source@...ux.davincidsp.com"
<davinci-linux-open-source@...ux.davincidsp.com>,
"devicetree-discuss@...ts.ozlabs.org"
<devicetree-discuss@...ts.ozlabs.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux@....linux.org.uk" <linux@....linux.org.uk>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Bedia, Vaibhav" <vaibhav.bedia@...com>,
"Rajashekhara, Sudhakar" <sudhakar.raj@...com>,
Tony Lindgren <tony@...mide.com>,
Wolfram Sang <wsa@...-dreams.de>,
"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>
Subject: RE: [PATCH 11/11] i2c: omap: enhance pinctrl support
On Fri, May 31, 2013 at 20:25:38, Strashko, Grygorii wrote:
> On 05/31/2013 01:13 PM, Hebbar Gururaja wrote:
> > Amend the I2C omap pin controller to optionally take a pin control
> > handle and set the state of the pins to:
> >
> > - "default" on boot, resume and before performing an i2c transfer
> > - "idle" after initial default, after resume default, and after each
> > i2c xfer
> > - "sleep" on suspend()
> >
> > By optionally putting the pins into sleep state in the suspend callback
> > we can accomplish two things.
> > - One is to minimize current leakage from pins and thus save power,
> > - second, we can prevent the IP from driving pins output in an
> > uncontrolled manner, which may happen if the power domain drops the
> > domain regulator.
> >
> > Note:
> > A .suspend & .resume callback is added which simply puts the pins to sleep
> > state upon suspend & are moved to default & idle state upon resume.
> >
> > If any of the above pin states are missing in dt, a warning message
> > about the missing state is displayed.
> > If certain pin-states are not available, to remove this warning message
> > pass respective state name with null phandler.
> >
> > (Changes based on i2c-nomadik.c)
> >
> > Signed-off-by: Hebbar Gururaja <gururaja.hebbar@...com>
> > Cc: Tony Lindgren <tony@...mide.com>
> > Cc: Wolfram Sang <wsa@...-dreams.de>
> > Cc: linux-omap@...r.kernel.org
> > Cc: linux-i2c@...r.kernel.org
> > ---
> > :100644 100644 e02f9e3... 588ba28... M drivers/i2c/busses/i2c-omap.c
> > drivers/i2c/busses/i2c-omap.c | 112 ++++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 105 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> > index e02f9e3..588ba28 100644
> > --- a/drivers/i2c/busses/i2c-omap.c
> > +++ b/drivers/i2c/busses/i2c-omap.c
> > @@ -214,7 +214,11 @@ struct omap_i2c_dev {
> > u16 westate;
> > u16 errata;
> >
> > - struct pinctrl *pins;
> > + /* Three pin states - default, idle & sleep */
> > + struct pinctrl *pinctrl;
> > + struct pinctrl_state *pins_default;
> > + struct pinctrl_state *pins_idle;
> > + struct pinctrl_state *pins_sleep;
> > };
> >
> > static const u8 reg_map_ip_v1[] = {
> > @@ -641,6 +645,11 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> > if (IS_ERR_VALUE(r))
> > goto out;
> >
> The current HWMOD framework configures PINs to enable state before
> enabling the device and
> switch PINs to idle state after disabling the device. Why here its done
> in different order?
AFAIK, in case of DT boot, "oh->mux" will be NULL. So hwmod will not change
Any pins.
> > + /* Optionaly enable pins to be muxed in and configured */
> > + if (!IS_ERR(dev->pins_default))
> > + if (pinctrl_select_state(dev->pinctrl, dev->pins_default))
> > + dev_err(dev->dev, "could not set default pins\n");
> > +
> > r = omap_i2c_wait_for_bb(dev);
> > if (r < 0)
> > goto out;
> > @@ -664,7 +673,13 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> >
> > out:
> > pm_runtime_mark_last_busy(dev->dev);
> > +
> > pm_runtime_put_autosuspend(dev->dev);
> > + /* Optionally let pins go into idle state */
> > + if (!IS_ERR(dev->pins_idle))
> > + if (pinctrl_select_state(dev->pinctrl, dev->pins_idle))
> > + dev_err(dev->dev, "could not set pins to idle state\n");
> > +
> > return r;
> > }
> >
> > @@ -1123,14 +1138,47 @@ omap_i2c_probe(struct platform_device *pdev)
> > dev->set_mpu_wkup_lat = pdata->set_mpu_wkup_lat;
> > }
> >
> > - dev->pins = devm_pinctrl_get_select_default(&pdev->dev);
> > - if (IS_ERR(dev->pins)) {
> > - if (PTR_ERR(dev->pins) == -EPROBE_DEFER)
> > + dev->pinctrl = devm_pinctrl_get(&pdev->dev);
> May be struct device ->pins->p can be used instead of dev->pinctrl?
> > + if (!IS_ERR(dev->pinctrl)) {
> > + dev->pins_default = pinctrl_lookup_state(dev->pinctrl,
> > + PINCTRL_STATE_DEFAULT);
> > + if (IS_ERR(dev->pins_default))
> > + dev_dbg(&pdev->dev, "could not get default pinstate\n");
> > + else
> > + if (pinctrl_select_state(dev->pinctrl,
> > + dev->pins_default))
> > + dev_err(&pdev->dev,
> > + "could not set default pinstate\n");
> Don't need to set Default pin state
> Default pins state is applied by DD framework automatically before
> device probing
> and stored in struct device ->pins->default_state
Correct.
> > +
> > + dev->pins_idle = pinctrl_lookup_state(dev->pinctrl,
> > + PINCTRL_STATE_IDLE);
> > + if (IS_ERR(dev->pins_idle))
> > + dev_dbg(&pdev->dev, "could not get idle pinstate\n");
> > + else
> > + /* If possible, let's idle until the first transfer */
> > + if (pinctrl_select_state(dev->pinctrl, dev->pins_idle))
> > + dev_err(&pdev->dev,
> > + "could not set idle pinstate\n");
> > +
> > + dev->pins_sleep = pinctrl_lookup_state(dev->pinctrl,
> > + PINCTRL_STATE_SLEEP);
> > + if (IS_ERR(dev->pins_sleep))
> > + dev_dbg(&pdev->dev, "could not get sleep pinstate\n");
> > + } else {
> > + if (PTR_ERR(dev->pinctrl) == -EPROBE_DEFER)
> > return -EPROBE_DEFER;
> >
> > - dev_warn(&pdev->dev, "did not get pins for i2c error: %li\n",
> > - PTR_ERR(dev->pins));
> > - dev->pins = NULL;
> > + /*
> > + * Since we continue even when pinctrl node is not found,
> > + * Invalidate pins as not available. This is to make sure that
> > + * IS_ERR(pins_xxx) results in failure when used.
> > + */
> > + dev->pins_default = ERR_PTR(-ENODATA);
> > + dev->pins_idle = ERR_PTR(-ENODATA);
> > + dev->pins_sleep = ERR_PTR(-ENODATA);
> > +
> > + dev_dbg(&pdev->dev, "did not get pins for i2c error: %li\n",
> > + PTR_ERR(dev->pinctrl));
> > }
> >
> > dev->dev = &pdev->dev;
> > @@ -1300,6 +1348,10 @@ static int omap_i2c_runtime_suspend(struct device *dev)
> > omap_i2c_read_reg(_dev, OMAP_I2C_STAT_REG);
> > }
> >
> > + if (!IS_ERR(_dev->pins_idle))
> > + if (pinctrl_select_state(_dev->pinctrl, _dev->pins_idle))
> > + dev_err(dev, "could not set pins to idle state\n");
> > +
> It's done in omap_i2c_xfer
Correct.
> > return 0;
> > }
> >
> > @@ -1311,13 +1363,59 @@ static int omap_i2c_runtime_resume(struct device *dev)
> > if (!_dev->regs)
> > return 0;
> >
> > + /* Optionally place the pins to the default state */
> > + if (!IS_ERR(_dev->pins_default))
> > + if (pinctrl_select_state(_dev->pinctrl, _dev->pins_default))
> > + dev_err(dev, "could not set pins to default state\n");
> > +
> It's done in omap_i2c_xfer
Hmmm. What is not a single transaction has taken place. In that case
omap_i2c_xfer() would have not been called.
> > __omap_i2c_init(_dev);
> >
> > return 0;
> > }
> > #endif /* CONFIG_PM_RUNTIME */
> >
> > +#ifdef CONFIG_PM_SLEEP
> > +static int omap_i2c_suspend(struct device *dev)
> Please, use .suspend_noirq() - it's possible that I2C will be used
> even after "device suspend" stage especially on SMP platforms((( ),
> but its prohibited to use it after "suspend_noirq" stage (
Ok will check about those implementation.
> > +{
> > + struct platform_device *pdev = to_platform_device(dev);
> > + struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
> > +
> > + pm_runtime_get_sync(dev);
> Here is the better way to detect late I2C activities during suspending:
> i2c_lock_adapter(&_dev->adapter);
>
> /* Check for active I2C transaction */
> if (atomic_read(&dev->power.usage_count) > 1) {
> dev_info(dev,
> "active I2C transaction detected - suspend aborted\n");
> return -EBUSY;
> }
>
> i2c_unlock_adapter(&_dev->adapter);
Hmm. Correct.
> > + if (omap_i2c_wait_for_bb(_dev) < 0) {
> > + pm_runtime_put_sync(dev);
> > + return -EBUSY;
> > + }
> > + pm_runtime_put_sync(dev);
> > +
> > + if (!IS_ERR(_dev->pins_sleep))
> > + if (pinctrl_select_state(_dev->pinctrl, _dev->pins_sleep))
> > + dev_err(dev, "could not set pins to sleep state\n");
> > +
> > + return 0;
> > +}
> Not sure it's right - Lest assume suspend_noirq() is used here.
> Then, at this point, OMAP device framework will disable device
> (_od_suspend_noirq()).
> But PINs will be switched to IDLE state before that. Is it ok?
> Possibly Kevin could clarify this point?
Seems he has a entirely different approach for this implementation.
> > +
> > +static int omap_i2c_resume(struct device *dev)
> Please, use .resume_noirq()
Ok.
> > +{
> The same is here - OMAP device framework will enable device
> (_od_suspend_noirq()) here.
> But PINs are still in IDLE state???
Needs to re-check. I will see how I can overcome this issue.
> > + struct platform_device *pdev = to_platform_device(dev);
> > + struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
> > +
> > + /* First go to the default state */
> > + if (!IS_ERR(_dev->pins_default))
> > + if (pinctrl_select_state(_dev->pinctrl, _dev->pins_default))
> > + dev_err(dev, "could not set pins to default state\n");
> > +
> > + /* Then let's idle the pins until the next transfer happens */
> > + if (!IS_ERR(_dev->pins_idle))
> > + if (pinctrl_select_state(_dev->pinctrl, _dev->pins_idle))
> > + dev_err(dev, "could not set pins to idle state\n");
> > +
> This is wrong - at this moment I2C device can be as in Enabled state
> as in Disabled
As above. Needs to re-check. I will see how I can overcome this issue.
> > + return 0;
> > +}
> > +#endif
> > +
> > +
> > static struct dev_pm_ops omap_i2c_pm_ops = {
> > + SET_SYSTEM_SLEEP_PM_OPS(omap_i2c_suspend, omap_i2c_resume)
> > SET_RUNTIME_PM_OPS(omap_i2c_runtime_suspend,
> > omap_i2c_runtime_resume, NULL)
> > };
>
>
Thanks for the thorough review.
Regards,
Gururaja
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