Subject: [PATCH v13 4/6] clk: Add rate constraints to clocks

From: [email-masked] (Tony Lindgren)
Date: Mon, 2 Feb 2015 08:12:37 -0800

* Geert Uytterhoeven <[email-masked]> [150202 00:03]:
> On Sun, Feb 1, 2015 at 11:18 PM, Mike Turquette <[email-masked]> wrote:
> > Quoting Tomeu Vizoso (2015-01-31 10:36:22)
> >> On 31 January 2015 at 02:31, Stephen Boyd <[email-masked]> wrote:
> >> > On 01/29, Stephen Boyd wrote:
> >> >> On 01/29/15 05:31, Geert Uytterhoeven wrote:
> >> >> > Hi Tomeu, Mike,
> >> >> >
> >> >> > On Fri, Jan 23, 2015 at 12:03 PM, Tomeu Vizoso
> >> >> > <[email-masked]> wrote:
> >> >> >> --- a/drivers/clk/clk.c
> >> >> >> +++ b/drivers/clk/clk.c
> >> >> >> @@ -2391,25 +2543,24 @@ int __clk_get(struct clk *clk)
> >> >> >>         return 1;
> >> >> >>  }
> >> >> >>
> >> >> >> -static void clk_core_put(struct clk_core *core)
> >> >> >> +void __clk_put(struct clk *clk)
> >> >> >>  {
> >> >> >>         struct module *owner;
> >> >> >>
> >> >> >> -       owner = core->owner;
> >> >> >> +       if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
> >> >> >> +               return;
> >> >> >>
> >> >> >>         clk_prepare_lock();
> >> >> >> -       kref_put(&core->ref, __clk_release);
> >> >> >> +
> >> >> >> +       hlist_del(&clk->child_node);
> >> >> >> +       clk_core_set_rate_nolock(clk->core, clk->core->req_rate);
> >> >> > At this point, clk->core->req_rate is still zero, causing
> >> >> > cpg_div6_clock_round_rate() to be called with a zero "rate" parameter,
> >> >> > e.g. on r8a7791:
> >> >>
> >> >> Hmm.. I wonder if we should assign core->req_rate to be the same as
> >> >> core->rate during __clk_init()? That would make this call to
> >> >> clk_core_set_rate_nolock() a nop in this case.
> >> >>
> >> >
> >> > Here's a patch to do this
> >> >
> >> > ---8<----
> >> > From: Stephen Boyd <[email-masked]>
> >> > Subject: [PATCH] clk: Assign a requested rate by default
> >> >
> >> > We need to assign a requested rate here so that we avoid
> >> > requesting a rate of 0 on clocks when we remove clock consumers.
> >>
> >> Hi, this looks good to me.
> >>
> >> Reviewed-by: Tomeu Vizoso <[email-masked]>
> >
> > It seems to fix the total boot failure on OMAPs, and hopefully does the
> > same for SH Mobile and others. I've squashed this into Tomeu's rate
> > constraints patch to maintain bisect.
> 
> Yes, it fixes shmobile. .round_rate() is now called with a sane value of rate.

Looks like next-20150202 now produces tons of the following errors,
these from omap4:

[   10.568206] ------------[ cut here ]------------
[   10.568206] WARNING: CPU: 0 PID: 1 at drivers/clk/clk.c:925 clk_disable+0x28/0x34()
[   10.568237] Modules linked in:
[   10.568237] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W       3.19.0-rc6-next-20150202 #2037
[   10.568237] Hardware name: Generic OMAP4 (Flattened Device Tree)
[   10.568267] [<c0015bdc>] (unwind_backtrace) from [<c001222c>] (show_stack+0x10/0x14)
[   10.568267] [<c001222c>] (show_stack) from [<c05d2014>] (dump_stack+0x84/0x9c)
[   10.568267] [<c05d2014>] (dump_stack) from [<c003ea90>] (warn_slowpath_common+0x7c/0xb8)
[   10.568298] [<c003ea90>] (warn_slowpath_common) from [<c003eb68>] (warn_slowpath_null+0x1c/0x24)
[   10.568298] [<c003eb68>] (warn_slowpath_null) from [<c04c1ffc>] (clk_disable+0x28/0x34)
[   10.568328] [<c04c1ffc>] (clk_disable) from [<c0025b3c>] (_disable_clocks+0x18/0x68)
[   10.568328] [<c0025b3c>] (_disable_clocks) from [<c0026f14>] (_idle+0x10c/0x214)
[   10.568328] [<c0026f14>] (_idle) from [<c0855fac>] (_setup+0x338/0x410)
[   10.568359] [<c0855fac>] (_setup) from [<c0027360>] (omap_hwmod_for_each+0x34/0x60)
[   10.568359] [<c0027360>] (omap_hwmod_for_each) from [<c08563c4>] (__omap_hwmod_setup_all+0x30/0x40)
[   10.568389] [<c08563c4>] (__omap_hwmod_setup_all) from [<c0008a04>] (do_one_initcall+0x80/0x1dc)
[   10.568389] [<c0008a04>] (do_one_initcall) from [<c0848ea0>] (kernel_init_freeable+0x204/0x2d0)
[   10.568420] [<c0848ea0>] (kernel_init_freeable) from [<c05cdab8>] (kernel_init+0x8/0xec)
[   10.568420] [<c05cdab8>] (kernel_init) from [<c000e790>] (ret_from_fork+0x14/0x24)
[   10.568420] ---[ end trace cb88537fdc8fa211 ]---

[   10.568450] ------------[ cut here ]------------
[   10.568450] WARNING: CPU: 0 PID: 1 at arch/arm/mach-omap2/dpll3xxx.c:436 omap3_noncore_dpll_enable+0xdc/0
x10c()
[   10.568450] Modules linked in:
[   10.568481] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W       3.19.0-rc6-next-20150202 #2037
[   10.568481] Hardware name: Generic OMAP4 (Flattened Device Tree)
[   10.568481] [<c0015bdc>] (unwind_backtrace) from [<c001222c>] (show_stack+0x10/0x14)
[   10.568511] [<c001222c>] (show_stack) from [<c05d2014>] (dump_stack+0x84/0x9c)
[   10.568511] [<c05d2014>] (dump_stack) from [<c003ea90>] (warn_slowpath_common+0x7c/0xb8)
[   10.568511] [<c003ea90>] (warn_slowpath_common) from [<c003eb68>] (warn_slowpath_null+0x1c/0x24)
[   10.568542] [<c003eb68>] (warn_slowpath_null) from [<c0035800>] (omap3_noncore_dpll_enable+0xdc/0x10c)
[   10.568542] [<c0035800>] (omap3_noncore_dpll_enable) from [<c04c0a10>] (clk_core_enable+0x60/0x9c)
[   10.568572] [<c04c0a10>] (clk_core_enable) from [<c04c09f0>] (clk_core_enable+0x40/0x9c)
[   10.568572] ---[ end trace cb88537fdc8fa212 ]---
...

Regards,

Tony