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

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Message-ID: <52E77D03.8090001@ti.com>
Date:	Tue, 28 Jan 2014 11:48:51 +0200
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Christoph Fritz <chf.fritz@...glemail.com>
CC:	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <pali.rohar@...il.com>,
	<pavel@....cz>, Tero Kristo <t-kristo@...com>,
	Nishanth Menon <nm@...com>
Subject: Re: [BISECTED] OMAP: DSS: clk rate mismatch

On 2014-01-28 11:35, Christoph Fritz wrote:
> On Tue, 2014-01-28 at 11:04 +0200, Tomi Valkeinen wrote:
>> On 2014-01-27 20:41, Christoph Fritz wrote:
>>> On Mon, 2014-01-27 at 19:30 +0200, Ivaylo Dimitrov wrote:
>>>> 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
>>>
>>> Here are also clock regressions since next-20140122 regarding
>>> dss_set_fck_rate() and sys_clkout2 occuring in my current patchset for a
>>> dm37xx100 board. Please see here:
>>
>> I presume you get a similar warning on your board? What rates does it
>> report?
> 
> None, dss_set_fck_rate() just fails so omapdss_dss exits with error -22.

Ok, then it's something else. That means clk_set_rate() fails.

If you can do some tests, you could print the rate that the
dss_set_fck_rate() is given, to see that it's something reasonable, and
also do a clk_get_rate(dss.dss_clk) to see that the clock itself is ok
and there's some valid rate there.

> To quote the cover-letter[1] of my board-support patch series here:
> 
> Due to a regression since next-20140122 the following errors are present:
> 
>  - pin sys_clkout2, which gets configured to 24 Mhz by the fourth patch
>    in this set, erroneously outputs only 12 Mhz.
>    Just out of curiosity, configuring it to 48 Mhz puts out desired 24 Mhz.
> 
>  - omap_dss, which gets configured by the third patch in this set, fails
>    to do 'dss_set_fck_rate(fck);' in
>    drivers/video/omap2/dss/dss.c:dss_setup_default_clock() which leads to:
> 
>     | omapdss_dss: probe of omapdss_dss failed with error -22
>     | omapdss CORE error: Failed to initialize DSS platform driver
>     | panel-dpi panel-dpi.0: failed to find video source 'dpi.0
> 
>   Both regressions seem to have something to do with the clock framework. 
>   Could this be related to the DT clock conversion patches?

No idea...

 Tomi



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