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

[Slava Ovsiienko]

> -----Original Message-----
> From: Thomas Monjalon <thomas at monjalon.net>
> Sent: Friday, July 17, 2020 18:19
> To: Slava Ovsiienko <viacheslavo at mellanox.com>
> Cc: dev at dpdk.org; Matan Azrad <matan at mellanox.com>; Raslan
> Darawsheh <rasland at mellanox.com>
> Subject: Re: [PATCH 3/3] common/mlx5: fix DevX register access opcode
> 
> 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.

 M-m-m-m, this is quite tiny 2-lines fix, we are going to squash it before rc2 😊
OK, will add the comment about dedicated opcode.

With best regards, Slava