svn commit: r298274 - head/sys/dev/spibus

[Patrick Kelsey]

On Tue, Apr 19, 2016 at 4:38 PM, Adrian Chadd <adrian.chadd at gmail.com>
wrote:

> On 19 April 2016 at 13:37, Patrick Kelsey <pkelsey at freebsd.org> wrote:
> >
> >
> > On Tue, Apr 19, 2016 at 4:21 PM, Ian Lepore <ian at freebsd.org> wrote:
> >>
> >> On Tue, 2016-04-19 at 13:17 -0700, Juli Mallett wrote:
> >> > Patrick Kelsey offered an mmcspi driver for FreeBSD, but nobody
> >> > seemed
> >> > interested.  I know of one proprietary branch of FreeBSD using it.
> >> > You might poke him if you want to know how he dealt with this, and if
> >> > you want to commit his driver.
> >> >
> >>
> >> Patrick is a committer, maybe he should just commit it. :)
> >
> >
> > What I believe originally held up that driver being committed (by others
> -
> > this was before my commit bit) was that I relied on some out-of-tree
> spibus
> > changes Luiz had made (as I recall, mainly being able to reserve the SPI
> bus
> > for multiple transactions), and getting those into the tree would have
> > required updating/testing other existing SPI drivers, based on feedback I
> > received at the time.  All I had was the RB450G that I developed and
> tested
> > the driver with, so I really couldn't address that issue, and then work
> took
> > me in some other direction entirely.  Some or all of these spibus changes
> > that I relied on might now be in the tree, I'm not sure offhand.  I am
> sure
> > though that a huge stack of other things I need to get through has
> > chronically kept me from updating that driver to current and retesting.
> >
> > When I wrote that driver, I put a lot of effort into testing it against
> as
> > many different cards as I could obtain at the time - I believe 30 or so
> in
> > total, all the details are in the code that was posted to the list back
> > then.  I encountered a number of strange/unexpected behaviors in that
> set of
> > cards, and all of that hard-won knowledge is in that driver, including a
> > much less complex fix for a shifted-response-data issue than you will
> see if
> > you look at the Linux mmcpsi driver (as I recall, the Linux driver has
> code
> > to arbitrarily bit-shift card response data, and to detect when that
> should
> > be done, but it turns out that can be avoided entirely by inserting idle
> > cycles in the right place when sending the command).
>
> Well, we should add the SPI bus reservation code and churn stuff as
> needed. I think that'd be a great addition.
>
> Do you have a patchset somewhere?
>
>

Just going from memory here - there is what I posted to the list, then at
some point Luiz took a stab at updating it to then-current (I should have a
copy of those somewhere - not sure where else they went, if anywhere), and
beyond that, I think there's a harmless but unnecessary conditional in the
original code that could be removed.

-Patrick