[PATCH v2 2/2] ARM: omap: hwmod: Make omap_hwmod_softreset wait for reset status

[Paul Walmsley]

Hi Rajendra,

On Wed, 11 Apr 2012, Rajendra Nayak wrote:

> The changes were done to fix up random L3 interconnect errors that
> Anand G was seeing(during i2c reset operation) on some customer platforms.

Okay.

> I seem to have completely overlooked the I2C_EN programming part done in 
> omap_i2c_reset() function when I did the patch.

No worries.

> While the patch did fix the issue for Anand, I guess it
> was because of the additional delay post reset, waiting on the
> RESETDONE bit and timing out, before accessing the i2c_con register.
> So looks like this patch should certainly be reverted but atleast some
> platforms/modules (the issue was seen on OMAP4/i2c) will need some
> delay between the omap_hwmod_softreset() call and any subsequent module
> register accesses.
> The patch from Fernando [1] can be quite useful if we can use the
> 'srst_udelay' field to populate the appropriate delay needed which can
> then be used up in omap_hwmod_softreset() function.
> I am out sick today, but I can try some on these lines tomorrow once
> I am in office, if the approach seems fine to you.

Sorry to hear that - I hope you feel better soon.

That approach sounds fine to me, but I don't think Fernando's patch will 
help with I2C..  Since it uses a custom reset function omap_i2c_reset(), 
the delay will actually need to go there.

Another option though is that it might be possible to generalize the 
_ocp_softreset() function to handle the I2C/HDQ cases, so they wouldn't 
need custom reset functions.  I'd guess that's probably 3.5 material, 
though.

> Btw, is [1] queued already by you/Benoit to go upstream or are there
> issues with it?
> 
> [1]
> http://lists.infradead.org/pipermail/linux-arm-kernel/2012-February/086713.html

Tony pulled it:

http://git.kernel.org/?p=linux/kernel/git/tmlind/linux-omap.git;a=commit;h=b8a633451951d149494076393698880453bf6bfe

Not sure when he plans to send it upstream, but I now think it should go 
up sooner as part of v3.4-rc fixes, to avoid any potential OCP bus errors.


- Paul