[RFC/PATCH 2/3] i2c: Fall back to emulated SMBus if the operation isn't supported natively
Adapter drivers might support only a subset of the SMBus operations natively. Those drivers currently have to manually emulate unsupported operations using I2C. Make the i2c_smbus_xfer() function fall back to i2c_smbus_xfer_emulated() when the adapter's .smbus_xfer() operation returns -EOPNOTSUPP, like it already does when the .smbus_xfer() operation isn't available at all. Signed-off-by: Laurent Pinchart --- drivers/i2c/i2c-core.c |9 +++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 8cfa660..16e750e 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -2113,8 +2113,8 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, union i2c_smbus_data *data) { unsigned long orig_jiffies; + s32 res = -EOPNOTSUPP; int try; - s32 res; flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB; @@ -2134,7 +2134,12 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, break; } i2c_unlock_adapter(adapter); - } else + } + + /* Fall back to i2c_smbus_xfer_emulated of the adapter doesn't implement +* native support for the SMBus operation. +*/ + if (res == -EOPNOTSUPP && adapter->algo->master_xfer) res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write, command, protocol, data); -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC/PATCH 2/3] i2c: Fall back to emulated SMBus if the operation isn't supported natively
Hi Laurent, On Tue, 26 Jun 2012 16:17:08 +0200, Laurent Pinchart wrote: > Adapter drivers might support only a subset of the SMBus operations > natively. Those drivers currently have to manually emulate unsupported > operations using I2C. > > Make the i2c_smbus_xfer() function fall back to > i2c_smbus_xfer_emulated() when the adapter's .smbus_xfer() operation > returns -EOPNOTSUPP, like it already does when the .smbus_xfer() > operation isn't available at all. > > Signed-off-by: Laurent Pinchart > --- > drivers/i2c/i2c-core.c |9 +++-- > 1 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index 8cfa660..16e750e 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -2113,8 +2113,8 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 > addr, unsigned short flags, > union i2c_smbus_data *data) > { > unsigned long orig_jiffies; > + s32 res = -EOPNOTSUPP; > int try; > - s32 res; > > flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB; > > @@ -2134,7 +2134,12 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 > addr, unsigned short flags, > break; > } > i2c_unlock_adapter(adapter); > - } else > + } > + > + /* Fall back to i2c_smbus_xfer_emulated of the adapter doesn't implement > + * native support for the SMBus operation. > + */ > + if (res == -EOPNOTSUPP && adapter->algo->master_xfer) > res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write, > command, protocol, data); > Looks good overall, but maybe the following variant would be preferable from a performance perspective: --- linux-3.5-rc7.orig/drivers/i2c/i2c-core.c 2012-07-17 16:35:42.566799611 +0200 +++ linux-3.5-rc7/drivers/i2c/i2c-core.c2012-07-17 16:59:55.334530352 +0200 @@ -2140,11 +2140,17 @@ s32 i2c_smbus_xfer(struct i2c_adapter *a break; } i2c_unlock_adapter(adapter); - } else - res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write, - command, protocol, data); - return res; + if (res != -EOPNOTSUPP || !adapter->algo->master_xfer) + return res; + /* +* Fall back to i2c_smbus_xfer_emulated if the adapter doesn't implement +* native support for the SMBus operation. +*/ + } + + return i2c_smbus_xfer_emulated(adapter, addr, flags, read_write, + command, protocol, data); } EXPORT_SYMBOL(i2c_smbus_xfer); What do you think? The advantage is that we can skip the tests for adapters which only implement adapter->algo->master_xfer(). -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC/PATCH 2/3] i2c: Fall back to emulated SMBus if the operation isn't supported natively
Hi Jean, On Tuesday 17 July 2012 17:02:43 Jean Delvare wrote: > On Tue, 26 Jun 2012 16:17:08 +0200, Laurent Pinchart wrote: > > Adapter drivers might support only a subset of the SMBus operations > > natively. Those drivers currently have to manually emulate unsupported > > operations using I2C. > > > > Make the i2c_smbus_xfer() function fall back to > > i2c_smbus_xfer_emulated() when the adapter's .smbus_xfer() operation > > returns -EOPNOTSUPP, like it already does when the .smbus_xfer() > > operation isn't available at all. > > > > Signed-off-by: Laurent Pinchart > > --- > > > > drivers/i2c/i2c-core.c |9 +++-- > > 1 files changed, 7 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > > index 8cfa660..16e750e 100644 > > --- a/drivers/i2c/i2c-core.c > > +++ b/drivers/i2c/i2c-core.c > > @@ -2113,8 +2113,8 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 > > addr, unsigned short flags, > >union i2c_smbus_data *data) > > { > > unsigned long orig_jiffies; > > + s32 res = -EOPNOTSUPP; > > int try; > > - s32 res; > > > > flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB; > > > > @@ -2134,7 +2134,12 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 > > addr, unsigned short flags, > > break; > > } > > i2c_unlock_adapter(adapter); > > - } else > > + } > > + > > + /* Fall back to i2c_smbus_xfer_emulated of the adapter doesn't implement > > +* native support for the SMBus operation. > > +*/ > > + if (res == -EOPNOTSUPP && adapter->algo->master_xfer) > > res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write, > > command, protocol, data); > > Looks good overall, but maybe the following variant would be preferable > from a performance perspective: > > --- linux-3.5-rc7.orig/drivers/i2c/i2c-core.c 2012-07-17 16:35:42.566799611 > +0200 +++ linux-3.5-rc7/drivers/i2c/i2c-core.c2012-07-17 > 16:59:55.334530352 +0200 @@ -2140,11 +2140,17 @@ s32 i2c_smbus_xfer(struct > i2c_adapter *a > break; > } > i2c_unlock_adapter(adapter); > - } else > - res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write, > - command, protocol, data); > > - return res; > + if (res != -EOPNOTSUPP || !adapter->algo->master_xfer) > + return res; > + /* > + * Fall back to i2c_smbus_xfer_emulated if the adapter doesn't implement > + * native support for the SMBus operation. > + */ > + } > + > + return i2c_smbus_xfer_emulated(adapter, addr, flags, read_write, > +command, protocol, data); > } > EXPORT_SYMBOL(i2c_smbus_xfer); > > > What do you think? The advantage is that we can skip the tests for > adapters which only implement adapter->algo->master_xfer(). I'm fine with that. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html