Re: [PATCH v1 1/1] i2c: designware: Fix hold and setup time issue

[sathyanarayanan kuppuswamy <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>]

On 06/02/2015 10:46 AM, Wolfram Sang wrote:
> On Mon, Apr 06, 2015 at 07:40:28PM -0700, Kuppuswamy Sathyanarayanan wrote:
> > If the device configuration is updated by firmware and
> > the information is not passed to driver via firmware
> > interfaces like ACPI or DT parameters, then that information
> > will be lost once the device either resets or suspends. This
> > patch checks the boot value of hold and setup time during
> > device probe and updates the driver hold and setup time params.
> > This fix will ensure that the updates to hold and setup time
> > values are not lost after device suspend or resets.
> >
> > Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> Adding Mika to CC.
>
> > ---
> >   drivers/i2c/busses/i2c-designware-core.c    | 37 +++++++++++++++++++++++++++++
> >   drivers/i2c/busses/i2c-designware-core.h    |  2 ++
> >   drivers/i2c/busses/i2c-designware-platdrv.c |  4 ++++
> >   3 files changed, 43 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
> > index 6e25c01..2598207 100644
> > --- a/drivers/i2c/busses/i2c-designware-core.c
> > +++ b/drivers/i2c/busses/i2c-designware-core.c
> > @@ -64,6 +64,7 @@
> >   #define DW_IC_RXFLR		0x78
> >   #define DW_IC_SDA_HOLD		0x7c
> >   #define DW_IC_TX_ABRT_SOURCE	0x80
> > +#define DW_IC_SDA_SETUP		0x94
> >   #define DW_IC_ENABLE_STATUS	0x9c
> >   #define DW_IC_COMP_PARAM_1	0xf4
> >   #define DW_IC_COMP_VERSION	0xf8
> > @@ -89,6 +90,9 @@
> >   					 DW_IC_INTR_TX_ABRT | \
> >   					 DW_IC_INTR_STOP_DET)
> >   
> > +#define DW_IC_DEFAULT_SDA_SETUP	0x64
> > +#define DW_IC_DEFAULT_SDA_HOLD	0x1
> > +
> >   #define DW_IC_STATUS_ACTIVITY	0x1
> >   
> >   #define DW_IC_ERR_TX_ABRT	0x1
> > @@ -271,6 +275,35 @@ static void __i2c_dw_enable(struct dw_i2c_dev *dev, bool enable)
> >   		 enable ? "en" : "dis");
> >   }
> >   
> > +/*
> > + * Update device default param values if its changed by
> > + * firmware
> > + */
> > +void dw_i2c_update_defaults(struct dw_i2c_dev *dev)
> > +{
> > +	int ret;
> > +
> > +	/*
> > +	 * make sure default is not updated by firmware
> > +	 * interfaces like OF or ACPI
> > +	 */
> > +
> > +	/* SDA hold time update */
> > +	if (!dev->sda_hold_time) {
> > +		ret = dw_readl(dev, DW_IC_SDA_HOLD);
> > +		if ((ret > 0) && (ret != DW_IC_DEFAULT_SDA_HOLD))
> > +			dev->sda_hold_time = ret;
> > +	}
> > +
> > +	/* SDA setup time update */
> > +	if (!dev->sda_setup_time) {
> > +		ret = dw_readl(dev, DW_IC_SDA_SETUP);
> > +		if ((ret > 0) && (ret != DW_IC_DEFAULT_SDA_SETUP))
> > +			dev->sda_setup_time = ret;
> > +	}
> > +}
> > +EXPORT_SYMBOL_GPL(dw_i2c_update_defaults);
> > +
> >   /**
> >    * i2c_dw_init() - initialize the designware i2c master hardware
> >    * @dev: device private data
> > @@ -368,6 +401,10 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
> >   				"Hardware too old to adjust SDA hold time.");
> >   	}
> >   
> > +	/* Configure SDA setup time if required */
> > +	if (dev->sda_setup_time)
> > +		dw_writel(dev, dev->sda_setup_time, DW_IC_SDA_SETUP);
> > +
> >   	/* Configure Tx/Rx FIFO threshold levels */
> >   	dw_writel(dev, dev->tx_fifo_depth / 2, DW_IC_TX_TL);
> >   	dw_writel(dev, 0, DW_IC_RX_TL);
> > diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
> > index 9630222..23ae2e8 100644
> > --- a/drivers/i2c/busses/i2c-designware-core.h
> > +++ b/drivers/i2c/busses/i2c-designware-core.h
> > @@ -98,6 +98,7 @@ struct dw_i2c_dev {
> >   	unsigned int		rx_fifo_depth;
> >   	int			rx_outstanding;
> >   	u32			sda_hold_time;
> > +	u32			sda_setup_time;
> >   	u32			sda_falling_time;
> >   	u32			scl_falling_time;
> >   	u16			ss_hcnt;
> > @@ -131,3 +132,4 @@ extern int i2c_dw_eval_lock_support(struct dw_i2c_dev *dev);
> >   #else
> >   static inline int i2c_dw_eval_lock_support(struct dw_i2c_dev *dev) { return 0; }
> >   #endif
> > +extern void dw_i2c_update_defaults(struct dw_i2c_dev *dev);
> > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> > index c270f5f..d8995d8 100644
> > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > @@ -233,6 +233,10 @@ static int dw_i2c_probe(struct platform_device *pdev)
> >   		dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
> >   		dev->adapter.nr = pdev->id;
> >   	}
> > +
> > +	/* call after firmware param update */
> > +	dw_i2c_update_defaults(dev);
> What about calling this from the pci driver?
Agreed. I will fix it in next version.
>

--
Sathyanarayanan Kuppuswamy
Android kernel developer

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