Re: [PATCH] ARM: OMAP2+: hwmod: Fix _wait_target_ready() for hwmods without sysc

[santosh.shilimkar@xxxxxxxxxx]

On 1/5/15 2:19 PM, Paul Walmsley wrote:
> + Santosh
>
> Hi Lokesh
>
> On Mon, 5 Jan 2015, Lokesh Vutla wrote:
> > On Saturday 03 January 2015 02:40 AM, Paul Walmsley wrote:
> > > On Thu, 18 Dec 2014, Roger Quadros wrote:
> > >
> > > > On 18/12/14 17:49, Roger Quadros wrote:
> > > > > There are quite a few hwmods that don't have sysconfig register and so
> > > > > _find_mpu_rt_port(oh) will return NULL thus preventing ready state check
> > > > > on those modules after the module is enabled.
> > >
> > > Hmm.  Any IP block that exposes registers that are accessible by the MPU
> > > should have an MPU register target port, even if there's no SYSCONFIG
> > > register.  And if an IP block doesn't have registers that are accessible
> > > from the MPU, then there shouldn't be much point to waiting for the module
> > > to become ready.
> > >
> > > Looks like the real problem is the test for oh->class->sysc before the
> > > call to _init_mpu_rt_base().  That was introduced by commit 6423d6df1440
> > > ("ARM: OMAP2+: hwmod: check for module address space during init"). It's
> > > not clear to me why that test was added, since _init_mpu_rt_base() doesn't
> > > do anything with oh->class->sysc or SYSCONFIG registers.
> > This was introduced by commit
> > 97597b962529 (ARM: OMAP2+: hwmod: Don't call _init_mpu_rt_base if no sysc)
>
> Yes, you're right.  I misread commit 6423d6df1440.
>
> > Patch description states that "there are few hwmod which doesn't have sysconfig registers and hence
> > no need to ioremap() them in early init code".
>
> The MPU register target port code doesn't only determine whether the
> hwmod code should map the IP block's address space.  It also determines
> whether or not the hwmod code needs to wait for the IP block to become
> ready after being enabled, so register accesses by non-hwmod code can
> succeed.
IIRC, Yes the intention was to skip the ioremap o.w there were some 
crashes seen. I am fine if that check is actually moved closer
to iormap as it should have been first place.

Regards,
Santosh
seen
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/