PL310 errata workarounds

[Rob Herring]

On Wed, Mar 19, 2014 at 4:22 PM, Marek Vasut <marex at denx.de> wrote:
> On Friday, March 14, 2014 at 08:14:06 PM, Rob Herring wrote:
>> On Fri, Mar 14, 2014 at 12:57 PM, Russell King - ARM Linux
>>
>> <linux at arm.linux.org.uk> wrote:
>> > On Fri, Mar 14, 2014 at 11:02:17AM -0500, Rob Herring wrote:
>> >> The obvious fix is to convert l2x0_flush_line to a function ptr which
>> >> just further complicates the code.
>> >
>> > I currently regard this code as unmaintainable, so right now I'm in the
>> > process of completely rewriting it, going back to the specs and checking
>> > what is required.  Sharing code between the L210, L220 and L310 looks
>> > good from the point of view of keeping the line count down, but actually
>> > they're quite different and have various different requirements.
>> >
>> > Out of those, L220 is the odd one out: all operations are background
>> > operations there, which means they have to be waited for.  Currently,
>> > if you have one of these, and you build a multiplatform kernel which
>> > includes PL310 support, you don't wait for any of these and you probably
>> > see a lot of data corruption as a result.
>>
>> Oops. I guess there are not many users as the L220 was primarily used
>> with the 1176 (and 11MP?) IIRC. I guess one of the primary 1176 based
>> platforms currently used is RPi, but it appears the BCM2835 doesn't
>> have an L2 (other than some custom L2 for the GPU).
>
> Won't Freescale i.MX35 help here ? It's 1136JF-S core and has some L2 cache.

No. 1136 uses L210. 1176 uses L220. There was the i.MX37 which had an
1176, but it was pretty short lived and never saw upstream support.

Rob