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

[Kevin Hilman]

Paul Walmsley <paul at pwsan.com> writes:

> Hi Tero,
>
> On Mon, 22 Oct 2012, Tero Kristo wrote:
>
>> 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 <t-kristo at ti.com>
>> Cc: Paul Walmsley <paul at pwsan.com>
>> Cc: Benoit Cousson <b-cousson at ti.com>
>> Cc: Venkatraman S <svenkatr at ti.com>
>
> 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.

Kevin