(+ Matt Porter, Joel Fernandes)
Hi Wolfram,
On Thu, 17 Apr 2014, Wolfram Sang wrote:
> thanks for the reply!
Always good to hear from you -
> > > If omap_device_alloc is given 2 or more "struct omap_hwmod" it will try
> > > to register the 'main_clk' of each of them with the same alias - "fck" -
> > > against the same device. This fails. So to avoid a warning, don't even
> > > try.
> > >
> > > Signed-off-by: NeilBrown <neilb@xxxxxxx>
> > > [wsa: ported to top-of-tree]
> > > Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxxxxxxxxx>
> >
> > What devices and hwmods cause this warning on AM335x? Ideally, there
> > should only be one hwmod per device. Usually when multiple hwmods are
> > stacked up for a device, it means that something isn't right - either the
> > hwmod data, or the device driver itself.
>
> I applied the patch because of the edma driver DT entry for the am335x.
> Check am33xx.dtsi, it has multiple hwmods.
I just took a look at the EDMA DT data vis-a-vis SPRUH73J Section 11.2.2
"Third-Party Transfer Controller (TPTC) Integration". This section
clearly indicates that the TPTCs have their own L3 Fast Interconnect slave
ports, marked as "CFG Slave". Cross-checking this with Table 2-1 "L3
Memory Map" indeed indicates that these three devices have their own 1MB
physical address ranges hanging off the L3.
So the EDMA DT data is flat-out wrong here and should not have been
merged. Looks like it was added by commit
505975d3802f8d3a3c0905f38056213d06997b36 ("ARM: dts: AM33XX: Add EDMA
support"). Matt, Joel, could you please fix this data? The TPTCs are
separate IP blocks with separate address ranges and MPU IRQs and should
have separate DT nodes.
> I also get this message printed for the d_can driver with am335x; they
> have two entries in drivers/clk/ti/clk-33xx.c. Probably as a workaround
> to match the desired clock name for the d_can driver? Didn't really
> investigate yet.
That's pretty weird. I wonder where the second fck alias is coming from?
The DT & hwmod data for those devices looks relatively straightforward.
Is the hwmod code adding fck aliases for both of the entries from the
clock file?
> > In the specific context of this patch, the problem would be: what if the
> > two hwmods have different main_clk entries? Which one should be
> > associated with the "fck" alias?
>
> Sadly, I am in a board bringup phase and can't really contribute to the
> discussions. Lots of other issues to tackle at the moment.
Understood. Good luck with your board -
- Paul
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