[dpdk-dev] [PATCH 3/3] common/mlx5: fix DevX register access opcode

[Thomas Monjalon]

17/07/2020 17:11, Slava Ovsiienko:
> From: Thomas Monjalon <thomas at monjalon.net>
> > 17/07/2020 16:28, Viacheslav Ovsiienko:
> > > The dedicated MLX5_CMD_OP_ACCESS_REGISTER_USER opcode must be
> > used to
> > > read hardware register content from unprotected mode.
> > 
> > Otherwise? What was broken?
> 
> Otherwise the MLX5_CMD_OP_ACCESS_REGISTER  was used, it returned EINVAL
> and register value was not read. It was supposed to enable ACCESS_REGISTER
> operation from user mode in kernel driver to read registers, but eventually
> it was replaced with ACCESS_REGISTER_USER dedicated operation.
> 
> mlx5 PMD does not rely on this feature strongly, if register reading fails
> it deduces the timestamp mode from reported timestamp counter
> frequency.

OK I think some of these explanations deserve to be in the commit log.