Re: [v2,02/10] i2c-i801: Move hostcfg set/reset to i801_access()

[Corey Minyard]

On 06/09/2016 04:39 AM, Benjamin Tissoires wrote:
> On May 29 2016 or thereabouts, Corey Minyard wrote:
> > From: Corey Minyard <cminyard@xxxxxxxxxx>
> >
> > The HSTCFG register save/restore was done in i2c_block_transaction,
> > but all the checks were already done in i801_access, so move it into
> > those checks.
> >
> > This results in a small savings of code, and moves some special
> > handing for I2C transactions into code that is already handling
> > special things for I2C transactions.
> >
> > Signed-off-by: Corey Minyard <cminyard@xxxxxxxxxx>
> > ---
> >   drivers/i2c/busses/i2c-i801.c | 41 +++++++++++++++++++----------------------
> >   1 file changed, 19 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
> > index 818c0c8..205f9d0 100644
> > --- a/drivers/i2c/busses/i2c-i801.c
> > +++ b/drivers/i2c/busses/i2c-i801.c
> > @@ -661,20 +661,6 @@ static int i801_block_transaction(struct i801_priv *priv,
> >   				  int command, int hwpec)
> >   {
> >   	int result = 0;
> > -	unsigned char hostc;
> > -
> > -	if (command == I2C_SMBUS_I2C_BLOCK_DATA) {
> > -		if (read_write == I2C_SMBUS_WRITE) {
> > -			/* set I2C_EN bit in configuration register */
> > -			pci_read_config_byte(priv->pci_dev, SMBHSTCFG, &hostc);
> > -			pci_write_config_byte(priv->pci_dev, SMBHSTCFG,
> > -					      hostc | SMBHSTCFG_I2C_EN);
> > -		} else if (!(priv->features & FEATURE_I2C_BLOCK_READ)) {
> > -			dev_err(&priv->pci_dev->dev,
> > -				"I2C block read is unsupported!\n");
> > -			return -EOPNOTSUPP;
> > -		}
> > -	}
> >   
> >   	if (read_write == I2C_SMBUS_WRITE
> >   	 || command == I2C_SMBUS_I2C_BLOCK_DATA) {
> > @@ -699,11 +685,6 @@ static int i801_block_transaction(struct i801_priv *priv,
> >   							     read_write,
> >   							     command);
> >   
> > -	if (command == I2C_SMBUS_I2C_BLOCK_DATA
> > -	 && read_write == I2C_SMBUS_WRITE) {
> > -		/* restore saved configuration register value */
> > -		pci_write_config_byte(priv->pci_dev, SMBHSTCFG, hostc);
> > -	}
> >   	return result;
> >   }
> >   
> > @@ -715,6 +696,7 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr,
> >   	int hwpec;
> >   	int block = 0;
> >   	int ret = 0, xact = 0;
> > +	int hostc = -1;
> >   	struct i801_priv *priv = i2c_get_adapdata(adap);
> >   
> >   	pm_runtime_get_sync(&priv->pci_dev->dev);
> > @@ -764,12 +746,24 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr,
> >   		/* NB: page 240 of ICH5 datasheet shows that the R/#W
> >   		 * bit should be cleared here, even when reading */
> >   		outb_p((addr & 0x7f) << 1, SMBHSTADD(priv));
> > -		if (read_write == I2C_SMBUS_READ) {
> > +		if (read_write == I2C_SMBUS_WRITE) {
> > +			unsigned char thostc;
> > +
> > +			outb_p(command, SMBHSTCMD(priv));
> > +			/* set I2C_EN bit in configuration register */
> > +			pci_read_config_byte(priv->pci_dev, SMBHSTCFG, &thostc);
> > +			pci_write_config_byte(priv->pci_dev, SMBHSTCFG,
> > +					      thostc | SMBHSTCFG_I2C_EN);
> > +			hostc = thostc;
> > +		} else if (!(priv->features & FEATURE_I2C_BLOCK_READ)) {
> nitpick: I'd prefer seeing:
> if (write) {
>    foo
> } else {
>    if (!FEATURE_I2C_BLOCK_READ) {
>      goto out
>    }
>    bar
> }
>
> It's equivalent but I feel like it's easier to understand.

First, thanks for all the reviews.  I really appreciate it.

On this particular change, it's moved from another location unchanged,
and it follows the style of the rest of the file.  I personally think 
it's better
to leave it like it is.

-corey

> Other than that, no strong opinion on the patch itself, but it's correct
> (the code path stays the same):
> Reviewed-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
>
> Cheers,
> Benjamin
>
> > +			dev_err(&priv->pci_dev->dev,
> > +				"I2C block read is unsupported!\n");
> > +			ret = -EOPNOTSUPP;
> > +			goto out;
> > +		} else
> >   			/* NB: page 240 of ICH5 datasheet also shows
> >   			 * that DATA1 is the cmd field when reading */
> >   			outb_p(command, SMBHSTDAT1(priv));
> > -		} else
> > -			outb_p(command, SMBHSTCMD(priv));
> >   		block = 1;
> >   		break;
> >   	default:
> > @@ -798,6 +792,9 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr,
> >   		outb_p(inb_p(SMBAUXCTL(priv)) &
> >   		       ~(SMBAUXCTL_CRC | SMBAUXCTL_E32B), SMBAUXCTL(priv));
> >   
> > +	if (hostc >= 0)
> > +		pci_write_config_byte(priv->pci_dev, SMBHSTCFG, hostc);
> > +
> >   	if (block)
> >   		goto out;
> >   	if (ret)