[PATCH] arm: pci: mark the dra7xx driver as broken

Hi Bjorn,

On Thursday 07 January 2016 08:12 PM, Bjorn Helgaas wrote:

On Thu, Jan 7, 2016 at 3:25 AM, Richard Cochran
[off-list ref] wrote:

quoted

On Thu, Jan 07, 2016 at 02:14:22PM +0530, Kishon Vijay Abraham I wrote:

quoted

In my point of view the driver is not broken as such but an independent piece
(reset) which is missing, since this driver compiles and works fine if that
reset piece is added. You are right in that this shouldn't have been probed
since it's known that the reset piece is missing. Maybe we should just set
"status = disabled" in dra7.dtsi and when that reset piece is added enable it
back in dra7-evm.dts?

That isn't strong enough, IMHO, since status=disabled is the default
for most every DTS item.  Maybe you could comment the PCI block out or
remove it and put a comment in about the missing piece and the lock up
behavior.  It is really a nasty bug to have the machine freeze up with
no output at all.  It took me some time to figure out what was going
on, and it would be a shame if someone else sets status=okay in their
board file and has to repeat the whole exercise.

It sounds like dra7xx is missing a piece of essential functionality.
If that's the case, what is the benefit of having it in the kernel at
all?  It makes work for everybody else (adapting to changes outside
the driver), but it sounds like nobody gets any benefit.

During the time pci-dra7xx driver was merged, the reset controller driver was
already being discussed in the list. And I didn't think it'll take this long
for it to be merged. And I didn't want pci driver development to be hampered by
these external pieces. That's why I sent the pci-dra7xx patches for merging.

IMHO merging pci-dra7xx helped to keep active development of the driver, though
I agree we should have kept mechanisms to keep the driver disabled either from
dt or in Kconfig and a way to tell that reset piece is missing if someone has
to enable the driver.

If somebody posts a patch to remove the driver entirely to
linux-pci at vger.kernel.org, we can discuss whether that's the right
thing to do.

I think that's not required now since Tony agreed to have pdata approach to
perform reset till reset controller is merged. I'll be posting patch for it soon.

Thanks
Kishon