[PATCH] ARM: OMAP5: DSS hwmod data

[Paul Walmsley]

Hi Archit,

On Thu, 8 May 2014, Archit Taneja wrote:

> Hi Paul,
> 
> On Thursday 08 May 2014 10:07 AM, Paul Walmsley wrote:
> > Hi,
> > 
> > On Wed, 12 Mar 2014, Tomi Valkeinen wrote:
> > 
> > > This patch adds hwmod data for omap5 display subsystem. I have tested this
> > > on
> > > omap5-uevm with a DSI panel. I cannot test omap5-uevm's hdmi output yet,
> > > as the
> > > mainline is missing omap5 HDMI driver.
> > > 
> > > I do see this when booting:
> > > 
> > >    omap_hwmod: dss_dispc: cannot be enabled for reset (3)
> > >    omap_hwmod: dss_dsi1: cannot be enabled for reset (3)
> > >    omap_hwmod: dss_dsi2: cannot be enabled for reset (3)
> > >    omap_hwmod: dss_hdmi: cannot be enabled for reset (3)
> > >    omap_hwmod: dss_rfbi: cannot be enabled for reset (3)
> > > 
> > > But at least DSI works just fine.
> > 
> > Am looking at this for v3.16.  But I think someone needs to take a look at
> > those warnings and figure out why they are happening.
> 
> We associate DSS clock domain's MODULEMODE bits only with the dss_core hwmod.
> The rest of the dss hwmods don't touch MODULEMODE.
> 
> Therefore, these hwmods cannot be enabled independently, and reset.
> 
> We don't face this issue in the omapdss driver since the platform devices
> corresponding to these hwmods have their parent as the platform device
> corresponding to 'dss_core'. This parent child-relation ensures that
> 'dss_core' is enabled when the a child calls a pm_runtime_get function.
> 
> The problem is that we have multiple hwmods which use the same MODULEMODE bit.
> There is no use-counting done when it comes to enabling/disabling modulemode.
> If there was such a thing, we could have provided MODULEMODE flags even for
> the children hwmods.

Thanks for the summary.  This is indeed a long-overdue item for the hwmod 
core code.  Can you please patch the hwmod core code to add this?  I'd 
suggest making the use-counting functionality conditional on a hwmod flag 
that you can set for all of the DSS hwmods.  (Ideally, the core code would 
detect that several modules share the same MODULEMODE bits, and 
automatically set it for those cases, but that seems a bit too complex for 
a first cut.)


- Paul