Subject: [PATCHv5 2/3] OMAP: I2C: Remove the reset in the init path

From: [email-masked] (Shubhrajyoti)
Date: Thu, 04 Aug 2011 22:11:18 +0530

On Wednesday 03 August 2011 04:57 AM, Kevin Hilman wrote:
> Shubhrajyoti D<[email-masked]>  writes:
>
>> -  The reset in the driver at init is not needed anymore as the
>>     hwmod framework takes care of reseting it.
>> -  Reset is removed from omap_i2c_init, which was called
>>     not only during probe, but also after time out and error handling.
>>     device_reset were added in those places to effect the reset.
> Not specifically related to this patch, as the reset behavior was
> already there, but do you know why the reset is needed after timeout and
> error handling?
>
> IOW, was the reset truly required in those cases, or was just the
> re-init necessary?
>
> To me doing a full reset of the IP in those cases sounds like a hack for
> a buggy driver.
My idea, there have been errata workaround that recommend reset in case 
of a
lockup that may happen after a warmreset.

>> -  Earlier the hwmod SYSC settings were over-written in the driver.
>>     Removing the same and letting the hwmod take care of the settings.
>> -  Clean up the SYSS_RESETDONE_MASK macro as it is no longer needed.
>> -  Clean up the SYSCONFIG SYSC bit defination macros.
>> -  Fix the typos in wakeup.
>>
>> Signed-off-by: Shubhrajyoti D<[email-masked]>
>> ---
>>   drivers/i2c/busses/i2c-omap.c |   83 +++++++++++------------------------------
>>   1 files changed, 22 insertions(+), 61 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
>> index 4e3256f..d8f4470 100644
>> --- a/drivers/i2c/busses/i2c-omap.c
>> +++ b/drivers/i2c/busses/i2c-omap.c
>> @@ -155,19 +155,6 @@ enum {
>>   #define OMAP_I2C_SYSTEST_SDA_O		(1<<  0)	/* SDA line drive out */
>>   #endif
>>
>> -/* OCP_SYSSTATUS bit definitions */
>> -#define SYSS_RESETDONE_MASK		(1<<  0)
>> -
>> -/* OCP_SYSCONFIG bit definitions */
>> -#define SYSC_CLOCKACTIVITY_MASK		(0x3<<  8)
>> -#define SYSC_SIDLEMODE_MASK		(0x3<<  3)
>> -#define SYSC_ENAWAKEUP_MASK		(1<<  2)
>> -#define SYSC_SOFTRESET_MASK		(1<<  1)
>> -#define SYSC_AUTOIDLE_MASK		(1<<  0)
>> -
>> -#define SYSC_IDLEMODE_SMART		0x2
>> -#define SYSC_CLOCKACTIVITY_FCLK		0x2
>> -
>>   /* Errata definitions */
>>   #define I2C_OMAP_ERRATA_I207		(1<<  0)
>>   #define I2C_OMAP3_1P153			(1<<  1)
>> @@ -182,6 +169,7 @@ struct omap_i2c_dev {
>>   	u32			latency;	/* maximum mpu wkup latency */
>>   	void			(*set_mpu_wkup_lat)(struct device *dev,
>>   						    long latency);
>> +	int			(*device_reset)(struct device *dev);
>>   	u32			speed;		/* Speed of bus in Khz */
>>   	u16			cmd_err;
>>   	u8			*buf;
>> @@ -317,60 +305,22 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
>>   	u16 psc = 0, scll = 0, sclh = 0, buf = 0;
>>   	u16 fsscll = 0, fssclh = 0, hsscll = 0, hssclh = 0;
>>   	unsigned long fclk_rate = 12000000;
>> -	unsigned long timeout;
>>   	unsigned long internal_clk = 0;
>>   	struct clk *fclk;
>>   	struct omap_i2c_bus_platform_data *pdata;
>>
>>   	pdata = dev->dev->platform_data;
>>
>> -	if (dev->rev>= OMAP_I2C_OMAP1_REV_2) {
>> -		/* Disable I2C controller before soft reset */
>> -		omap_i2c_write_reg(dev, OMAP_I2C_CON_REG,
>> -			omap_i2c_read_reg(dev, OMAP_I2C_CON_REG)&
>> -				~(OMAP_I2C_CON_EN));
>> -
>> -		omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, SYSC_SOFTRESET_MASK);
>> -		/* For some reason we need to set the EN bit before the
>> -		 * reset done bit gets set. */
>> -		timeout = jiffies + OMAP_I2C_TIMEOUT;
>> -		omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
>> -		while (!(omap_i2c_read_reg(dev, OMAP_I2C_SYSS_REG)&
>> -			 SYSS_RESETDONE_MASK)) {
>> -			if (time_after(jiffies, timeout)) {
>> -				dev_warn(dev->dev, "timeout waiting "
>> -						"for controller reset\n");
>> -				return -ETIMEDOUT;
>> -			}
>> -			msleep(1);
>> -		}
>> -
>> -		/* SYSC register is cleared by the reset; rewrite it */
>> -		if (dev->rev == OMAP_I2C_REV_ON_2430) {
>> -
>> -			omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG,
>> -					   SYSC_AUTOIDLE_MASK);
>> -
>> -		} else if (dev->rev>= OMAP_I2C_REV_ON_3430) {
>> -			dev->syscstate = SYSC_AUTOIDLE_MASK;
>> -			dev->syscstate |= SYSC_ENAWAKEUP_MASK;
>> -			dev->syscstate |= (SYSC_IDLEMODE_SMART<<
>> -			      __ffs(SYSC_SIDLEMODE_MASK));
>> -			dev->syscstate |= (SYSC_CLOCKACTIVITY_FCLK<<
>> -			      __ffs(SYSC_CLOCKACTIVITY_MASK));
>> -
>> -			omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG,
>> -							dev->syscstate);
>> -			/*
>> -			 * Enabling all wakup sources to stop I2C freezing on
>> -			 * WFI instruction.
>> -			 * REVISIT: Some wkup sources might not be needed.
>> -			 */
>> -			dev->westate = OMAP_I2C_WE_ALL;
>> -			if (dev->rev<  OMAP_I2C_REV_ON_3530_4430)
>> -				omap_i2c_write_reg(dev, OMAP_I2C_WE_REG,
>> -								dev->westate);
>> -		}
>> +	if (dev->rev>= OMAP_I2C_REV_ON_3430) {
>> +		/*
>> +		 * Enabling all wakeup sources to stop I2C freezing on
>> +		 * WFI instruction.
>> +		 * REVISIT: Some wakeup sources might not be needed.
>> +		 */
>> +		dev->westate = OMAP_I2C_WE_ALL;
>> +		if (dev->rev<  OMAP_I2C_REV_ON_3530_4430)
>> +			omap_i2c_write_reg(dev, OMAP_I2C_WE_REG,
>> +							dev->westate);
>>   	}
>>   	omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, 0);
>>
>> @@ -595,6 +545,11 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
>>   		return r;
>>   	if (r == 0) {
>>   		dev_err(dev->dev, "controller timed out\n");
>> +		if (dev->device_reset != NULL) {
> No need for the '!= NULL'
>
>                  if (dev->device_reset)
>
> is more typical.
>
> And based on my comments in 1/3, this would become device_shutdown.
>
>> +			r = dev->device_reset(dev->dev);
>> +			if (r<  0)
>> +				dev_err(dev->dev, "reset failed\n");
>> +		}
>>   		omap_i2c_init(dev);
>>   		return -ETIMEDOUT;
>>   	}
>> @@ -605,6 +560,11 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
>>   	/* We have an error */
>>   	if (dev->cmd_err&  (OMAP_I2C_STAT_AL | OMAP_I2C_STAT_ROVR |
>>   			    OMAP_I2C_STAT_XUDF)) {
>> +		if (dev->device_reset != NULL) {
>> +			r = dev->device_reset(dev->dev);
>> +			if (r<  0)
>> +				dev_err(dev->dev, "reset failed\n");
>> +		}
>>   		omap_i2c_init(dev);
>>   		return -EIO;
>>   	}
>> @@ -1005,6 +965,7 @@ omap_i2c_probe(struct platform_device *pdev)
>>   	if (pdata != NULL) {
>>   		speed = pdata->clkrate;
>>   		dev->set_mpu_wkup_lat = pdata->set_mpu_wkup_lat;
>> +		dev->device_reset = pdata->device_reset;
>>   	} else {
>>   		speed = 100;	/* Default speed */
>>   		dev->set_mpu_wkup_lat = NULL;
> Kevin