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    SubjectRe: [RFC PATCH] clk: add extension API
    Hi,

    On Thu, May 31, 2012 at 11:31:31AM +0300, Peter De Schrijver wrote:
    > On Thu, May 31, 2012 at 10:18:42AM +0200, Felipe Balbi wrote:
    > > * PGP Signed by an unknown key
    > >
    > > On Thu, May 31, 2012 at 10:51:25AM +0300, Peter De Schrijver wrote:
    > > > On Wed, May 30, 2012 at 10:52:31AM +0200, Stephen Boyd wrote:
    > > > > On 5/29/2012 2:58 AM, Peter De Schrijver wrote:
    > > > > > Add an extension API for clocks. This allows clocktypes to provide extensions
    > > > > > for features which are uncommon and cannot be easily mapped onto normal clock
    > > > > > framework concecpts. eg: resetting blocks, configuring clock phase etc.
    > > > >
    > > > > This seems rather generic. Why not add more specific APIs/concepts like
    > > > > clk_reset(), clk_set_phase(), etc.? If they don't map, maybe we should
    > > > > make them map.
    > > > >
    > > >
    > > > Some of those might be very SoC specific. Eg OMAP doesn't need software
    > > > controlled modulereset. I don't think we should add a new function to the
    > >
    > > it depends on what you call modulereset. We have soft-reset logic hidden
    > > under the hood, it's done before device creation, so drivers (most of
    > > them) assume we're probe with the IP in reset state.
    > >
    > > What I wonder most is if this should be done at the clock level or at
    > > the device level. In the end you reset the IP block, not the clock,
    > > right ?
    >
    > Yes. but, every block has at least 1 clock and thus the mapping is identical
    > down to the register level. Ie. we could do this outside the clockframework,

    What if a module needs two clocks and you drive the reset on both of the
    clocks ? What would happen ?

    > but then we would have the keep a list of IDs (1 per module) which the drivers
    > can use to call some tegra reset function which would in the end use registers
    > in the same memory area to cause a reset. (the registers controlling
    > modulereset are interleaved with those controlling the enable/disable of the
    > main moduleclock and bitpositions are identical)

    Well, under a generic device-level API, you could just call an internal
    clk_reset() function because you know which clocks feed into which
    devices anyway. It could look something like:

    on Tegra:

    device_reset(dev)
    -> dev_pm_domain->reset()
    -> tegra_periph_reset()

    on OMAP:

    device_reset(dev)
    -> dev_pm_domain->reset()
    -> omap_hwmod_reset()


    btw:

    tegra_periph_reset(....)
    {
    tegra_periph_reset_assert(...);
    udelay(2);
    tegra_periph_reset_deassert(...);
    }

    --
    balbi
    [unhandled content-type:application/pgp-signature]
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