On Wed, Apr 20, 2016 at 05:17:56PM +0200, Peter Rosin wrote: > Add i2c_lock_bus() and i2c_unlock_bus(), which call the new lock_bus and > unlock_bus ops in the adapter. These funcs/ops take an additional flags > argument that indicates for what purpose the adapter is locked. > > There are two flags, I2C_LOCK_ADAPTER and I2C_LOCK_SEGMENT, but they are > both implemented the same. For now. Locking the adapter means that the > whole bus is locked, locking the segment means that only the current bus > segment is locked (i.e. i2c traffic on the parent side of mux is still > allowed even if the child side of the mux is locked. > > Also support a trylock_bus op (but no function to call it, as it is not > expected to be needed outside of the i2c core). > > Implement i2c_lock_adapter/i2c_unlock_adapter in terms of the new locking > scheme (i.e. lock with the I2C_LOCK_ADAPTER flag). > > Annotate some of the locking with explicit I2C_LOCK_SEGMENT flags. Can you explain a little why it is SEGMENT and not ADAPTER here? That probably makes it easier to get into this patch. And to double check my understanding: I was surprised to not see any i2c_lock_adapter() or I2C_LOCK_ADAPTER in action. This is because muxes call I2C_LOCK_SEGMENT on their parent which in case of the parent being the root adapter is essentially the same as I2C_LOCK_ADAPTER. Correct? > > Signed-off-by: Peter Rosin <peda@xxxxxxxxxx> > --- > drivers/i2c/i2c-core.c | 46 ++++++++++++++++++++++++++++------------------ > include/linux/i2c.h | 28 ++++++++++++++++++++++++++-- > 2 files changed, 54 insertions(+), 20 deletions(-) > > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index 0f2f8484e8ec..21f46d011c33 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -960,10 +960,12 @@ static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr) > } > > /** > - * i2c_lock_adapter - Get exclusive access to an I2C bus segment > + * i2c_adapter_lock_bus - Get exclusive access to an I2C bus segment > * @adapter: Target I2C bus segment > + * @flags: I2C_LOCK_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENT > + * locks only this branch in the adapter tree > */ I think this kerneldoc should be moved to i2c_lock_adapter and/or i2c_lock_bus() which are now in i2c.h. This is what users will use, not this static, adapter-specific implementation. I think it is enough to have a comment here explaining what is special in handling adapters. Thanks, Wolfram -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
