Re: [Xen-devel] [RFC PATCH 22/31] xen/arm: Add Xen changes to SCPI protocol

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 05/12/2017 21:20, Stefano Stabellini wrote:
> On Thu, 9 Nov 2017, Oleksandr Tyshchenko wrote:
> > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> >
> > Modify the direct ported SCPI Message Protocol driver to be
> > functional inside Xen.
> >
> > As SCPI Message protocol driver expects mailbox to be registed,
> > find and initialize mailbox before probing it.
> >
> > Include "wrappers.h" which contains all required things the direct
> > ported code relies on.
> >
> > Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> > CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> > CC: Julien Grall <julien.grall@xxxxxxxxxx>
> As far as drivers ported from Linux go, this looks pretty clean in terms
> of changes and nasty glue code required to get it to work.
>
> The wrappers.h header is not too bad. The question remains on whether we
> should keep the #if 0 to retain "textual compatibility" with Linux, or
> we should just bite the bullet and apply the changes. If we commit them
> as a separate patch, we can always dig out the difference between the
> original driver and the Xen version using git.
>
> Julien, what do you think?
When I see the diff of that series:

 50 files changed, 4822 insertions(+), 862 deletions(-)

this is a rather huge series for benefits that we still don't know (e.g 
we don't have any numbers). Based on the current discussion, it looks 
like the design will change quite a lot. So in entire honesty, I haven't 
spent and will not spend much times look at the code itself until we get 
an agreement on the benefits.
However I had a brief look at the code and I raised quiet a few time the 
eyebrow at the glue code. I saw that mutex was converted spinlock 
without any justification (see patch #20).
Anyway, Oleksandr promised to come back with numbers and investigating 
the discussion. We should probably wait that before looking at this 
series in more details.
Cheers,

--
Julien Grall

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