Re: [PATCH] OMAP PM interface, version 3

[Tony Lindgren <tony@atomide.com>]

* Paul Walmsley <paul@pwsan.com> [080717 05:00]:
> 
> Hello everyone,
> 
> this is the third version of the OMAP PM interface patch.
> 
> Major changes since the second revision:
> 
> 1. set_max_mpu_wakeup_lat() has been added.  This is intended to limit
>    the amount of time needed for the MPU to wake up and enter a device
>    driver's interrupt handler.
> 
> 2. set_max_dma_lat() has been renamed to set_max_sdma_lat()
> 
> 3. omap_pm_dsp_get_opp_table() and struct omap_opp have been added for
>    future DSPBridge/CPUFreq use.  omap_pm_if_init() now takes pointers
>    to struct omap_opp arrays that are intended to be passed in from the
>    board-*.c files.
> 
> 4. Interface documentation has been moved to the 
>    include/asm-arm/arch-omap/omap-pm.h file.
> 
> 5. Documentation updated and moved into Documentation/arm/OMAP/omap_pm
> 
> 
> Further comments welcome,

I think we need to run this by LKML, linux-arm-kernel, and linux-pm
before we integrate these. Can you repost these for comments one
more time so we get comments from other mailing lists?

Thanks,

Tony


> 
> 
> - Paul 
> 
> ---------------------------------
> 
> This message proposes the third version of a power management
> interface (the "OMAP PM interface") for the linux-omap kernel tree.
> 
> It includes a general device driver PM interface, along with some
> specialized interfaces for CPUFreq, DSPBridge, and the
> powerdomain/clockdomain code.  This message focuses on the general
> device driver portion, since it is most relevant to the larger
> community of OMAP device driver developers.
> 
> The interface is intended to allow drivers to take advantage of OMAP
> power management features:
> 
> - without locking drivers into a particular underlying implementation;
> 
> - without adding constraints that are specific to particular OMAP
>   variants; and
> 
> - without affecting other architectures.
> 
> The device driver portion of the interface covers four types of PM
> constraints:
> 
> 1. Set the maximum MPU wakeup latency
> 
> 2. Set the maximum device wakeup latency
> 
> 3. Set the maximum system DMA transfer start latency (CORE pwrdm)
> 
> 4. Set the minimum bus throughput needed by a device
> 
> 
> These are described in more detail in the patch.
> 
> This interface is intended to be temporary, to survive only until the
> Linux PM QoS layer supports these features.
> 
> This interface is a collaborative product of many people from Nokia
> and TI: Karthik Dasu, Jouni Högander, Tony Lindgren, Rajendra Nayak,
> Sakari Poussa, Veeramanikandan Raju, Anand Sawant, Igor Stoppa, Paul
> Walmsley, and Richard Woodruff.
> 
> Included in the patch is a 'no-op' implementation that documents the
> interface and emits debug messages.  Rajendra Nayak at TI has
> developed an initial implementation of the OMAP PM interface that
> relies mostly on TI's Shared Resource Framework.  Also under
> development is an implementation of the OMAP PM code that uses the
> existing Linux PM QoS code.
> 
> 
> Comments welcomed,
> 
> - Paul
> 
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