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    SubjectRe: [alsa-devel] [RFC PATCH] ASoC: wm8731: let codec to manage clock by itself
    On Tue, Feb 03, 2015 at 05:53:48PM +0100, Lars-Peter Clausen wrote:
    > On 02/03/2015 01:44 PM, Mark Brown wrote:
    > >On Tue, Feb 03, 2015 at 08:54:57AM +0100, Manuel Lauss wrote:
    > >
    > >>+ wm8731->mclk = devm_clk_get(&spi->dev, "mclk");
    > >>+ if (IS_ERR(wm8731->mclk)) {
    > >>+ wm8731->mclk = NULL;
    > >>+ dev_warn(&spi->dev, "assuming static MCLK\n");
    > >>+ }
    > >
    > >This is broken for both deferred probe and in the case where the clock
    > >API genuinely returns a NULL clock. Other than that it's the kind of
    > >thing that we've done for some other drivers, though it's not good to
    > >have to do this. Check them for correct behaviour.
    >
    > Ideally we'd introduce a {devm_}clk_get_optional(), with the same semantics
    > as gpiod_get_optional(), which handles the finer details of differentiating
    > between clock specified, but not yet probed, clock specified, but
    > incorrectly and no clock specified, so this doesn't have to be done over and
    > over by each driver.

    No, we don't need to. It clk_get() already knows this distinction, and
    it appropriately returns -ENOENT vs -EPROBE_DEFER according to whether
    there's a clock specified in DT or not.

    --
    FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
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