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    SubjectRe: [PATCH 1/6] mmc: dw_mmc: remove the deprecated "clock-freq-min-max" property
    On Fri, Feb 23, 2018 at 06:16:39PM +0200, Andy Shevchenko wrote:
    > On Fri, Feb 23, 2018 at 4:19 PM, Shawn Lin <shawn.lin@rock-chips.com> wrote:
    > > On 2018/2/23 21:27, Andy Shevchenko wrote:
    > >> On Fri, Feb 23, 2018 at 8:41 AM, Jaehoon Chung <jh80.chung@samsung.com>
    > >> wrote:
    > >>>
    > >>> 'clock-freq-min-max' property had already deprecated.
    > >>> Remove the 'clock-freq-min-max' property that is kept to maintain
    > >>> the compatibility.
    > >>
    > >>
    > >> Removing a property without telling the user what to expect is a bad
    > >> idea and ABI breakage.
    > >>
    > >
    > > What's the general process to remove a property?
    > >
    > > I guess we should do:
    > > 1) deprecate it in the first place and remove it from all upstream DT

    Yes

    > > 2) wait some long enough days for expecting the stale of all old DTB
    > > containing that property

    Yes. How long that is depends on the platform. I think the minimum is 1
    release cycle. Some stable platforms are years. If there are other DT
    changes with new features everyone should want/need, then that can be a
    decision point.

    Given this is a shared IP block it's harder to know, so you may need to
    err on the longer side.

    > > 3) remove the functionality of the deprecated property from the driver
    > > but still leave some warning there

    I'd say add a warning in step 1 and combine 3 and 4.

    > > 4) remove the left warning finally
    >
    > I don't know. Perhaps Rob can shed a light here.
    > But I would really OK with removal of some of such properties from
    > some drivers where it's more burden to keep them.
    >
    > > And for the ABI breakage, we should add something in Documentation/ABI
    > > /obsolete or Documentation/ABI/removed ?

    It is only an ABI break if someone notices.

    Rob

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