linux-kernel - Re: [PATCH] ARM: OMAP2+: hwmod: Fix _wait_target

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Message-ID: <20150102172935.GD3298@atomide.com>
Date:	Fri, 2 Jan 2015 09:29:35 -0800
From:	Tony Lindgren <tony@...mide.com>
To:	Roger Quadros <rogerq@...com>
Cc:	Lokesh Vutla <lokeshvutla@...com>, Paul Walmsley <paul@...an.com>,
	t-kristo@...com, nm@...com, nsekhar@...com, bcousson@...libre.com,
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: OMAP2+: hwmod: Fix _wait_target_ready() for hwmods
 without sysc

* Roger Quadros <rogerq@...com> [141219 01:08]:
> Lokesh,
> 
> On 19/12/14 07:21, Lokesh Vutla wrote:
> > Hi Roger,
> > On Thursday 18 December 2014 09:22 PM, Roger Quadros wrote:
> >> Fixing up Paul's email id.
> >>
> >> cheers,
> >> -roger
> >>
> >> 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.
> >>>
> >>> This can potentially cause a bus access error if the module is accessed
> >>> before the module is ready.
> >>>
> >>> Get rid of the redundant _find_mpu_rt_port() check from the _wait_target_ready()
> >>> funcion for all the SoCs. The following PRCM register access that checks the
> >>> module ready state has nothing to do with module's SYSCONFIG or mpu_rt_port.
> > Yes, makes sense. This patch looks good to me.
> > Tested this on AM437x-gp-evm.

Roger, if the modules don't have sysconfig registers, care to check
if we actually really need hwmod for those modules then?

I know hwmod is managing runtime PM gate clocks for devices with
clkctrl_offs. But if that's all we need hwmod for in the non-sysc
cases, then it might make sense to manage the gate clocks in the
clock framework directly instead for those devices.

Of course that's more of a long term project, but at least we should
be aware of the dependencies here :)

> > May be good idea to warn every time if enabling of module is failed?
> > Unrelated to this patch though.
> 
> Yes, failing to be ready is serious enough for a warning. Care to send a separate patch for that?

Yeah that sounds like a separate patch.

Regards,

Tony
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