linux-kernel - Re: [PATCH 01/26] ARM: OMAP: dmtimer: Remove setting of clk parent indirectly through platform hook

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Date:	Wed, 7 May 2014 15:04:27 -0700
From:	Tony Lindgren <tony@...mide.com>
To:	Joel Fernandes <joelf@...com>
Cc:	Linux OMAP List <linux-omap@...r.kernel.org>,
	Linux ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/26] ARM: OMAP: dmtimer: Remove setting of clk parent
 indirectly through platform hook

* Joel Fernandes <joelf@...com> [140507 14:44]:
> On 05/07/2014 10:19 AM, Tony Lindgren wrote:
> > * Joel Fernandes <joelf@...com> [140424 14:44]:
> >> There is a platform specific hook just for OMAP1 to set its clk parent.  Remove
> >> this hook and have OMAP1 set its parent in omap1_dm_timer_init.  If OMAP1 is
> >> ever migrated to clock framework, the correct way to do this would be through
> >> clk_set_parent like other platforms.
> >>
> >> Signed-off-by: Joel Fernandes <joelf@...com>
> >> ---
> >>  arch/arm/mach-omap1/timer.c                |    8 +++++++-
> >>  arch/arm/plat-omap/dmtimer.c               |    8 +++-----
> >>  include/linux/platform_data/dmtimer-omap.h |    2 --
> >>  3 files changed, 10 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/arch/arm/mach-omap1/timer.c b/arch/arm/mach-omap1/timer.c
> >> index bde7a35..4b9c604 100644
> >> --- a/arch/arm/mach-omap1/timer.c
> >> +++ b/arch/arm/mach-omap1/timer.c
> >> @@ -140,7 +140,13 @@ static int __init omap1_dm_timer_init(void)
> >>  			goto err_free_pdata;
> >>  		}
> >>  
> >> -		pdata->set_timer_src = omap1_dm_timer_set_src;
> >> +		/*
> >> +		 * Since OMAP1 doesn't support clock framework, set timer clock
> >> +		 * source to 32KHz here instead of expecting it to be set by
> >> +		 * dmtimer code.
> >> +		 */
> >> +		omap1_dm_timer_set_src(pdev, 0x01);
> >> +
> >>  		pdata->timer_capability = OMAP_TIMER_ALWON |
> >>  				OMAP_TIMER_NEEDS_RESET | OMAP_TIMER_HAS_DSP_IRQ;
> >>  
> > 
> > This does not sound right, omap1 does support clock framework just fine.
> > It is not using the common clock framework though.
> > 
> > This breaks omap_dm_timer_set_source() for sure. Setting the source
> > during init is not a right solution here. Probably best to keep the
> > pdata hook around, drivers can support pdata and DT data together
> > just fine.
> 
> Actually pdata hook in this case is used only in 1 place, and is OMAP1
> specific so I felt its better to clean it up.
> 
> Can you elaborate a bit more on why it breaks? I have no way of testing
> OMAP1 without hardware.
> 
> What difference is it to set MOD_CONF_CTRL_1 in omap1's
> arch_initcall(omap1_dm_timer_init)  versus doing so later?

You're making a driver behave in a different way for omap1
compared to omap2+ where selecting the clock source won't work
for omap1.

Regards,

Tony
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