linux-kernel - Re: [BISECTED] OMAP: DSS: clk rate mismatch

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Message-ID: <52E76EE0.2060006@ti.com>
Date:	Tue, 28 Jan 2014 10:48:32 +0200
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
CC:	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <pali.rohar@...il.com>,
	<pavel@....cz>
Subject: Re: [BISECTED] OMAP: DSS: clk rate mismatch

On 2014-01-28 09:50, Tomi Valkeinen wrote:
> On 2014-01-27 19:30, Ivaylo Dimitrov wrote:
>> Hi Tomi,
>>
>> linux-next-20140124 DSS is broken on N900  - display stays black (there
>> is some noise though). I booted the kernel with qemu and it gives the
>> following warning:
>>
>> [    0.623779] DSS: set fck to 172800000
>> [    0.624237] ------------[ cut here ]------------
>> [    0.624298] WARNING: CPU: 0 PID: 1 at
>> drivers/video/omap2/dss/dss.c:497 dss_set_fck_rate+0x68/0x8c()
>> [    0.624359] clk rate mismatch: 288000000 != 172800000
> 
> That says that the omapdss tries to set the func clock to 172.8 MHz, but
> after setting the rate, the clock is at 288 MHz.
> 
> I just hit the same warning with beagle-xm yesterday, with v3.13-rc6 +
> DSS device tree patches, although it might be a different thing. I see
> that the actual clock is lower than what omapdss tries to set, you have
> the other way around.
> 
> The beagle-xm issue is related to a clk-divider fix I have sent some
> time ago:
> 
> http://mid.gmane.org/1383736008-22764-1-git-send-email-tomi.valkeinen@ti.com

I made a somewhat hacky quickfix for beagle. Applying that and the
clk-divider from the link above makes things work for me. However, as I
said, the issue with n900 might be different, but it'd be interesting to
hear if it has any effect.

 Tomi


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