linux-kernel - Re: [PATCH 1/4] drivers/bus: Added Freescale Management Complex APIs

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Message-ID: <1411081392.13320.15.camel@snotra.buserror.net>
Date:	Thu, 18 Sep 2014 18:03:12 -0500
From:	Scott Wood <scottwood@...escale.com>
To:	Kim Phillips <kim.phillips@...escale.com>
CC:	Alexander Graf <agraf@...e.de>,
	German Rivera <German.Rivera@...escale.com>,
	"<gregkh@...uxfoundation.org>" <gregkh@...uxfoundation.org>,
	"<arnd@...db.de>" <arnd@...db.de>,
	"<linux-kernel@...r.kernel.org>" <linux-kernel@...r.kernel.org>,
	"<stuart.yoder@...escale.com>" <stuart.yoder@...escale.com>,
	"<linuxppc-release@...ux.freescale.net>" 
	<linuxppc-release@...ux.freescale.net>
Subject: Re: [PATCH 1/4] drivers/bus: Added Freescale Management Complex APIs

On Thu, 2014-09-18 at 15:22 -0500, Kim Phillips wrote:
> On Thu, 18 Sep 2014 15:14:03 +0200
> Alexander Graf <agraf@...e.de> wrote:
> 
> > > Am 18.09.2014 um 06:17 schrieb German Rivera <German.Rivera@...escale.com>:
> > > 
> > >> On 09/15/2014 06:44 PM, Kim Phillips wrote:
> > >> On Thu, 11 Sep 2014 12:34:21 -0500
> > >> "J. German Rivera" <German.Rivera@...escale.com> wrote:
> > >> 
> > >>> From: "J. German Rivera" <German.Rivera@...escale.com>
> > >>> 
> > >>> APIs to access the Management Complex (MC) hardware
> > >>> module of Freescale LS2 SoCs. This patch includes
> > >>> APIs to check the MC firmware version and to manipulate
> > >>> DPRC objects in the MC.
> > >>> 
> > >>> Signed-off-by: J. German Rivera <German.Rivera@...escale.com>
> > >>> Signed-off-by: Stuart Yoder <stuart.yoder@...escale.com>
> > >>> ---
> > >>>  drivers/bus/fsl-mc/dpmng.c         |   93 +++++
> > >>>  drivers/bus/fsl-mc/dprc.c          |  504 +++++++++++++++++++++++
> > >>>  drivers/bus/fsl-mc/fsl_dpmng_cmd.h |   83 ++++
> > >>>  drivers/bus/fsl-mc/fsl_dprc_cmd.h  |  545 +++++++++++++++++++++++++
> > >>>  drivers/bus/fsl-mc/fsl_mc_sys.c    |  237 +++++++++++
> > >>>  include/linux/fsl_dpmng.h          |  120 ++++++
> > >>>  include/linux/fsl_dprc.h           |  790 ++++++++++++++++++++++++++++++++++++
> > >>>  include/linux/fsl_mc_cmd.h         |  182 +++++++++
> > >>>  include/linux/fsl_mc_sys.h         |   81 ++++
> > >>>  9 files changed, 2635 insertions(+)
> > >>>  create mode 100644 drivers/bus/fsl-mc/dpmng.c
> > >>>  create mode 100644 drivers/bus/fsl-mc/dprc.c
> > >>>  create mode 100644 drivers/bus/fsl-mc/fsl_dpmng_cmd.h
> > >>>  create mode 100644 drivers/bus/fsl-mc/fsl_dprc_cmd.h
> > >>>  create mode 100644 drivers/bus/fsl-mc/fsl_mc_sys.c
> > >>>  create mode 100644 include/linux/fsl_dpmng.h
> > >>>  create mode 100644 include/linux/fsl_dprc.h
> > >>>  create mode 100644 include/linux/fsl_mc_cmd.h
> > >>>  create mode 100644 include/linux/fsl_mc_sys.h
> > >> 
> > >> the fsl prefix in the filename fsl_dpmng_cmd.h is redundant with
> > >> its directory name fsl-mc/.  Note that I find dashes ('-') in
> > >> filenames make them easier to type: is there a reason we're using
> > >> underscores here?
> > > This is a convention that we decided early on '-' for directory names
> > > and '_' for file names.
> 
> based on what?

I agree with Kim here.

> > >>> +/**
> > >>> + * @brief    Management Complex firmware version information
> > >>> + */
> > >>> +#define MC_VER_MAJOR 2
> > >>> +#define MC_VER_MINOR 0
> > >> 
> > >> code should be adjusted to run on all *compatible* versions of h/w,
> > >> not strictly the one set in these defines.
> > > This comment is not precise enough be actionable.
> > > What exactly you want to be changed  here?
> > 
> >
> > I think the easy thing to do is to convert the exact version check
> > into a ranged version check: have minimum and maximum versions you
> > support. Or a list of exact versions you support. Or not check for the
> > version at all - or only for the major version and guarantee that the
> > major version indicates backwards compatibility.
> >
> yes, this was my point: elsewhere I noticed the code denies to run
> iff those defines are not matched exactly: that code should change
> to run as Alex describes.

Also keep in mind that in the future we may need to support multiple
versions that behave differently.

-Scott


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