From: Kevin Hilman <khilman@ti.com>
To: J.Weitzel@phytec.de
Cc: linux-omap@vger.kernel.org, b-cousson@ti.com,
andy.green@linaro.org, patches@linaro.org, andy@warmcat.com,
tony@atomide.com, peter.maydell@linaro.org, ben-linux@fluff.org
Subject: Re: [PATCH v3] ARM: omap4: i2c reset regs postidle
Date: Wed, 18 May 2011 16:09:01 +0200 [thread overview]
Message-ID: <87oc30t81u.fsf@ti.com> (raw)
In-Reply-To: <1305724078.6272.24.camel@lws-weitzel> (Jan Weitzel's message of "Wed, 18 May 2011 15:07:58 +0200")
Jan Weitzel <J.Weitzel@phytec.de> writes:
> Am Dienstag, den 17.05.2011, 16:12 +0200 schrieb Kevin Hilman:
>> Jan Weitzel <j.weitzel@phytec.de> writes:
>>
>> > omap4430 get i2c timeouts at each access after an NACK message.
>> > OMAP_I2C_FLAG_RESET_REGS_POSTIDLE fix it.
>>
>> We need a little better changelog here. Specifically, *why* does this
>> flag fix the problem? What exactly is going wrong such that this fix
>> is needed.
>>
>> Does this happen all the time? only when off-mode is used? etc.
> Yes all time. i2cdetect say "controller timed out" every two adresses.
>
>> Looking closer at how this flag is used in the driver, I think the
>> driver's usage of runtime PM is a bit broken. I'm not sure if it's
>> related to this problem, but I'll send a short series in a little bit to
>> clean up the runtime PM usage, and get rid of the dev->idle flag which
>> duplicates usage counting already provided by runtime PM.
> In the isr OMAP_I2C_STAT_NACK set OMAP_I2C_CON_REG to OMAP_I2C_CON_STP,
> clearing all other flags. Maybe this is wrong?
>
> On OMAP3 the OMAP_I2C_CON_REG flags are set again in the
> OMAP_I2C_FLAG_RESET_REGS_POSTIDLE path of omap_i2c_unidle.
> I am not sure if this is also the right place for OMAP4
Right, and I'm not sure either. That's why we need a better
explanation/changelog about exactly what is happening and why this is
the right fix.
Kevin
next prev parent reply other threads:[~2011-05-18 14:09 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-21 11:47 [PATCH] ARM: omap4: i2c reset regs postidle Jan Weitzel
2011-04-21 12:13 ` Andy Green
2011-05-16 7:56 ` Jan Weitzel
2011-05-16 8:13 ` Andy Green
2011-05-16 9:18 ` [PATCH v2] " Jan Weitzel
2011-05-16 17:16 ` Cousson, Benoit
2011-05-17 9:26 ` [PATCH v3] " Jan Weitzel
2011-05-17 14:12 ` Kevin Hilman
2011-05-18 13:07 ` Jan Weitzel
2011-05-18 14:09 ` Kevin Hilman [this message]
2011-06-14 10:05 ` [RFC] ARM: OMAP2+ i2c NACK without STP Jan Weitzel
2011-06-14 10:24 ` Tony Lindgren
[not found] ` <20110614102409.GN3352-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
2011-06-14 10:54 ` [PATCH] " Jan Weitzel
2011-12-27 14:48 ` T Krishnamoorthy, Balaji
[not found] ` <CANrkHUZ530H+0+YKy2QJPFbwUQ1zqD=OaSrF6ByTbpx6eU421Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-01-04 0:07 ` Kevin Hilman
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