Re: [PATCH AUTOSEL 5.5 219/542] ARM: OMAP2+: use separate IOMMU pdata to fix DRA7 IPU1 boot

From: Sasha Levin
Date: Thu Feb 20 2020 - 11:49:47 EST

On Fri, Feb 14, 2020 at 12:34:58PM -0600, Suman Anna wrote:
Hi Sasha,

On 2/14/20 9:43 AM, Sasha Levin wrote:
From: Suman Anna <s-anna@xxxxxx>

[ Upstream commit 4601832f40501efc3c2fd264a5a69bd1ac17d520 ]

The IPU1 MMU has been using common IOMMU pdata quirks defined and
used by all IPU IOMMU devices on OMAP4 and beyond. Separate out the
pdata for IPU1 MMU with the additional .set_pwrdm_constraint ops
plugged in, so that the IPU1 power domain can be restricted to ON
state during the boot and active period of the IPU1 remote processor.
This eliminates the pre-conditions for the IPU1 boot issue as
described in commit afe518400bdb ("iommu/omap: fix boot issue on
remoteprocs with AMMU/Unicache").

1. RET is not a valid target power domain state on DRA7 platforms,
and IPU power domain is normally programmed for OFF. The IPU1
still fails to boot though, and an unclearable l3_noc error is
thrown currently on 4.14 kernel without this fix. This behavior
is slightly different from previous 4.9 LTS kernel.
2. The fix is currently applied only to IPU1 on DRA7xx SoC, as the
other affected processors on OMAP4/OMAP5/DRA7 are in domains
that are not entering RET. IPU2 on DRA7 is in CORE power domain
which is only programmed for ON power state. The fix can be easily
scaled if these domains do hit RET in the future.
3. The issue was not seen on current DRA7 platforms if any of the
DSP remote processors were booted and using one of the GPTimers
5, 6, 7 or 8 on previous 4.9 LTS kernel. This was due to the
errata fix for i874 implemented in commit 1cbabcb9807e ("ARM:
DRA7: clockdomain: Implement timer workaround for errata i874")
which keeps the IPU1 power domain from entering RET when the
timers are active. But the timer workaround did not make any
difference on 4.14 kernel, and an l3_noc error was seen still
without this fix.

Signed-off-by: Suman Anna <s-anna@xxxxxx>
Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

And drop this one as well, since mainline doesn't yet boot
the processors, so this is not needed for stable queue.

Now dropped, thank you.