Paul Walmsley had written, on 09/24/2010 12:17 PM, the following:
On Fri, 24 Sep 2010, Paul Walmsley wrote:
On Fri, 24 Sep 2010, Nishanth Menon wrote:
The intent of omap_has_featureX() is to ensure that the drivers dont do
cpu_is_omap123(). Now if we had OMAP dma driver which has DMA chaining - what
options do we have DMA driver?
a) we introduce it based on cpu_is_omap123() -> bad bad nightmare for
maintenance
b) we introduce it based on module h/w block(TI internal terminology "IP
block") revision -> unfortunately no luck in some of the h/w blocks.
c) we use if (omap_has_dma_chaining())
d) you pass in errata/feature flags via a platform_data struct, like
McBSP, McSPI, MMC, MUSB, I2C, etc. already do on OMAP. On OMAP1, which
doesn't have hwmod support, you set your platform_data in your OMAP1
integration code. On OMAP2+ (which has hwmod support), you define your
errata/feature flags and any other integration data that you need to pass
via the struct omap_hwmod.dev_attr field, then pass that data via struct
platform_data in the OMAP2+ integration code.
Just to clarify something that may be unclear: there's no problem with
calling cpu_is_omapXXXX(), or any other OMAP core-specific function, from
the OMAP<->driver integration code, living in arch/arm/*omap*. The
results of those functions can then be passed through platform_data. But
there is a problem with calling OMAP core-specific functions directly from
the driver code itself, since driver code should be completely
platform-independent -- e.g., the same DMA controller could exist on OMAP,
DaVinci, etc.
yep. your comment makes sense now. thanks for clarifying. NAK from me as
well.
--
Regards,
Nishanth Menon
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