> > Allocate only one DMA channel for I2C and share it for both Tx and Rx. > > Since I2C supports only half duplex, there is no impact on perf with > > this. > > > > Signed-off-by: Akhil R <akhilrajeev@xxxxxxxxxx> > > --- > > v1->v2: Remove WARN_ON for DMA channel mismatch. There is only one > > channel in use with this change. > > > > drivers/i2c/busses/i2c-tegra.c | 54 ++++++++++------------------------ > > 1 file changed, 15 insertions(+), 39 deletions(-) > > I'm a little confused by this. All device trees already list the very > same reference for both TX and RX DMA channels in the I2C nodes, so > these channels are already effectively shared, aren't they? The value given in DT refers to the slave-id of an I2C instance and not the channel number. Each I2C instance was in-effect using two different DMA channels with the same slave-id. This change is to free up the extra DMA channel since both will not be used simultaneously. > > So all this does is to get rid of the duplicated pointer? In practice, > is the DMA channel pointer going to point to the exact same memory or > are these separate objects that happen to point to the same hardware > resource? They are indeed separate hardware resource itself. As I described above, two separate DMA channels were in use for each I2C instance. > > In either case, I think the commit message should clarify that. Also, a > few minor nits below... Agreed with the other comments. Regards, Akhil
