Re: [PATCHv2 0/5] OMAP DSS HWMOD fixes

From: Tomi Valkeinen <tomi.valkeinen@ti.com>
To: Archit Taneja <archit@ti.com>
Cc: "paul@pwsan.com" <paul@pwsan.com>,
	"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
	"Cousson, Benoit" <b-cousson@ti.com>
Subject: Re: [PATCHv2 0/5] OMAP DSS HWMOD fixes
Date: Mon, 08 Aug 2011 15:03:47 +0300	[thread overview]
Message-ID: <1312805027.1747.4.camel@lappyti> (raw)
In-Reply-To: <4E3FCBDC.1080208@ti.com>

On Mon, 2011-08-08 at 17:13 +0530, Archit Taneja wrote:
> Hi,
> 
> On Monday 08 August 2011 02:45 PM, Valkeinen, Tomi wrote:
> > Second try with the DSS HWMODs
> >
> > This set fixes the DSS clocks in HWMOD data, and implements a new reset
> > mechanism for dss_core.
> >
> > The new dss_reset function doesn't actually do a reset, it just enables all DSS
> > clocks and waits for the reset to complete. This should be better approach than
> > actually doing a reset, because:
> >
> > OMAP4 - dss_core HW doesn't contain a SW reset bit so doing a reset is
> > impossible. But after power-on we need to enable all DSS clocks and wait for
> > the power-on reset to complete.
> >
> > OMAP2/3 - dss_core does have a SW reset bit, but resetting dss_core also resets
> > all the other DSS modules. This means that the other modules could be left
> > uninitialized, as the hwmod code handles all modules independently, and in this
> > case initializes only dss_core's registers. Thus dss_core's reset shouldn't be
> > used, and we should only verify that the power-on reset has completed.
> 
> If the bootloader enables DSS, we need to do a reset so that DSS2 driver 
> can start with DSS HW in a clean state. With this patch set, how do we 
> take care of such a scenario?

We don't. That should be done in a future patch.

I think we should extend this reset function, and disable the LCD
outputs and reset the clock switches there.

I didn't want to do that yet as I wanted to fix the current problem with
the reset first and I don't have an environment where to test it. I hope
you can help here =).

 Tomi