[RFC] ARM: OMAP: hwmod: wait for sysreset complete after enabling hwmod

On Tuesday 23 October 2012 07:58 PM, Kevin Hilman wrote:

Paul Walmsley [off-list ref] writes:

quoted

Hi Tero,

On Mon, 22 Oct 2012, Tero Kristo wrote:

quoted

When waking up from off-mode, some IP blocks are reset automatically by
hardware. For this reason, software must wait until the reset has
completed before attempting to access the IP block.

This patch fixes for example the bug introduced by commit
6c31b2150ff96755d24e0ab6d6fea08a7bf5c44c ("mmc: omap_hsmmc: remove access
to SYSCONFIG register"), in which the MMC IP block is reset during
off-mode entry, but the code expects the module to be already available
during the execution of context restore.

Signed-off-by: Tero Kristo <redacted>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Benoit Cousson <redacted>
Cc: Venkatraman S <redacted>

What do you think about these modifications?  The code is quite similar to
what was in the _ocp_softreset() function, so just moved it into a
function.  Also moved the callsite from the end of _enable_sysc() to the
beginning, which makes more sense to me, but would like to get your
opinion.

FYI, after some more testing with this patch, I noticed that this patch
(and the original from Tero) cause some sluggishness on UART1 console my
37xx/EVM platform as soon as off-mode is enabled (even without the UART
autosuspend timeouts enabled.)  I don't see this on any other OMAP3
platform but all the others I have have UART3 console (in PER), the EVM
is the only one with UART1 console (in CORE.)

I haven't debugged this any furhter, but thought it should be reported
before this gets merged.

Trying to shoot in the dark but the UART sluggishness I observed in the
past on OMAP4 was due to improper setting of sysconfig which is
what $subject + Tero's patch is dealing with. Good to check the
value of UART sysconfig before and after the offmode entry to
see if the smart-idle/smart-idle wakeup setting getting disturbed
for some reason.

Below is the OMAP4 commit am referring to.

commit 5ae256dcd91bf308826a4ac19598b27ebb86a536
Author: Santosh Shilimkar [off-list ref]
Date:   Fri Apr 13 23:25:04 2012 +0530

     ARM: OMAP: serial: Fix the ocp smart idlemode handling bug

Regards,
Santosh