On 6/29/22 14:47, Krzysztof Adamski wrote:
W dniu 26.06.2021 o 12:27, Raviteja Narayanam pisze:
Xilinx I2C IP has two modes of operation, both of which implement
I2C transactions. The only difference from sw perspective is the
programming sequence for these modes.
Dynamic mode -> Simple to program, less number of steps in sequence.
Standard mode -> Gives flexibility, more number of steps in sequence.
In dynamic mode, during the i2c-read transactions, if there is a
delay(> 200us) between the register writes (address & byte count),
read transaction fails. On a system with load, this scenario is
occurring frequently.
To avoid this, switch to standard mode if there is a read request.
Added a quirk to identify the IP version effected by this and follow
the standard mode.
Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xxxxxxxxxx>
[...]
If those two modes only differ in software complexity but we are not
able to support only the simpler one and we have support for the more
complicated (standard mode) anyways, we know that standard mode
can handle or the cases while dynamic mode cannot, we also know that
dynamic mode is broken on some versions of the core, why do we actually
keep support for dynamic mode?
If I recall it right, the dynamic mode was supposed to handle transfers
longer than 255 Bytes, which the core cannot do in Standard mode. It is
needed e.g. by Atmel MXT touch controller. I spent a lot of time
debugging the race conditions in the XIIC, which I ultimately fixed (the
patches are upstream), but the long transfers I rather fixed in the MXT
driver instead.
I also recall there was supposed to be some update for the XIIC core
coming with newer vivado, but I might be wrong about that.
