Re: [PATCH] omap: hwmod: add syss reset done flags to omap2, omap3 hwmods

["Avinash.H.M." <avinashhm@ti.com>]

On Fri, Mar 25, 2011 at 11:23:38AM -0600, Paul Walmsley wrote:
> Hi,
> 
> On Fri, 25 Mar 2011, Cousson, Benoit wrote:
> 
> > On 3/25/2011 6:38 AM, Paul Walmsley wrote:
> > > > > On Thu, 24 Feb 2011, Avinash.H.M wrote:
> > > > > > Some of the omap2, omap3 peripherals support software reset. This
> > > > > > can be done through the softreset bit in sysconfig register.
> > > > > > The reset status can be checked through resetdone bit of
> > > > > > sysstatus register. syss_has_reset_status is added to the hwmod
> > > > > > database of peripherals which have resetdone bit in sysstatus
> > > > > > register.
> > > > > > 
> > > > > > Cc: Rajendra Nayak<rnayak@ti.com>
> > > > > > Cc: Paul Walmsley<paul@pwsan.com>
> > > > > > Cc: Benoit Cousson<b-cousson@ti.com>
> > > > > > Cc: Kevin Hilman<khilman@ti.com>
> > > > > > Reviewed-by: Govindraj.R<govindraj.raja@ti.com>
> > > > > > Signed-off-by: Avinash.H.M<avinashhm@ti.com>
> > > 
> > > This patch is causing I2C softreset timeouts in the hwmod layer on OMAP2
> > > and 3.  Could you please take a look at this and figure out what is going
> > > on?
> > 
> > I think this is probably due to the nasty I2C softreset bug with discussed
> > last year with Paul Brady.
> > 
> > AFAIR, the I2C cannot be reset by just writing to the SYSCONFIG softreset bit.
> > You need to play with other registers too.

Thanks Benoit. You are right. 

The TRM Section '18.3.1.3.2 Software Reset' explains the steps for
softresetting I2C. The steps are below:

1. Ensure that the module is disabled (clear the I2Ci.I2C_CON[15] I2C_EN
bit to 0).
2. Set the I2Ci.I2C_SYSC[1] SRST bit to 1.
3. Enable the module by setting I2Ci.I2C_CON[15] I2C_EN bit to 1.
4. Check the I2Ci.I2C_SYSS[0] RDONE bit until it is set to 1 to indicate
the software reset is complete.

> 
> Thanks Benoît.
> 
> So then, Avinash, you might need to create a custom hwmod class 
> reset function for the I2C block (viz., struct omap_hwmod_class.reset)

OK Paul. I'll add the I2C_CON register and follow the above sequence as
suggested in the TRM in the custom I2C reset function.

br,

- Avinash

> 
> > Avinash,
> > You should try to look at 3430 or 3630 errata. You will probably find the bug
> > I'm referring to.
> 
> 
> - Paul

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