On 4/5/22 16:20, Dave Stevenson wrote:
Hi,
If we can initialise the DSI host before the bridge for the
pre_enable, then all the configuration moves to the atomic_pre_enable
and there should be no need to have the delay.
I can't 100% guarantee that, but one of the folks on the Pi forums is
using [1] which does that, and is reporting it working well. (He's
also using the DSI85 to take 2 DSI links and drive 2 LVDS single link
panels)
It seems to me that checking whether the bridge got correctly
initialized is orthogonal to the aforementioned patchset though ?
It's the delay that is ugly.
You do need to wait a little after the initialization and before
checking the status, so that delay is not going away no matter how you
frob with the DSI bridge.
Put the check in atomic_enable which will be slightly later than
configuration in pre_enable? Check that sufficient jiffies have passed
if you needed.
Or wire up the IRQ line from the SN65DSI83 rather than polling the IRQ
Status register. Delayed workqueue if the IRQ isn't wired up.
Are you able to do such deferred non-atomic operations in atomic_enable
callback ?
If I read it right your log message is triggered by any bit being set
in REG_IRQ_STAT. So an inconveniently timed correctable DSI error will
set bit 4 and log the error even though it's been corrected. Likewise
bit 7 / CHA_SYNCH_ERR could get triggered by an H or V sync packet
being received in that 10-12ms window (we're in atomic_enable, so
video is already running).
There should be no bits set in the IRQ_STAT register if everything works
as it should.
If it's the PLL being unlocked that is the issue then it should only
be checking bit 0. Or possibly reading the actual PLL lock status from
REG_RC_LVDS_PLL_PLL_EN_STAT. Although as we've already checked that
the PLL is locked via REG_RC_LVDS_PLL_PLL_EN_STAT earlier in the
atomic_enable, I'm now a little confused as to the condition you are
actually wanting to detect.
Any outstanding errors which are currently hidden and only show up
sporadically at the worst possible moment.
[...]
