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    SubjectRe: [PATCH 4/4] serial/arc-uart: switch to devicetree based probing
    On Saturday 09 February 2013 04:31 AM, Grant Likely wrote:
    > On Fri, 11 Jan 2013 11:50:23 +0530, Vineet Gupta <Vineet.Gupta1@synopsys.com> wrote:
    >> +- clock-frequency : the input clock frequency for the UART
    >> +- baud : baud rate for UART
    > change 'baud' to 'current-speed'. There is already precedence for this
    > with other serial devices.

    While I'm OK with this - I can only see of_serial.c following the rule :-)
    More importantly I'm not clear about the logistics of this fix. Obviously this has
    a bearing on DT files in arch/arc/boot/*. So are such changes (platform + driver)
    routed thru the subsystem tree or the arch tree or bits from both with
    bisectability not considered - which feels wrong. We have to also consider the
    fact that Greg has closed the tty/serial for 3.9. So while I have no objection to
    your comment, it seems that the it needs to wait till 3.9-rc1 - or is there an
    alternate way.

    >
    >> @@ -673,8 +693,18 @@ static int __init arc_serial_probe_earlyprintk(struct platform_device *pdev)
    >> static int arc_serial_probe(struct platform_device *pdev)
    >> {
    >> int rc, dev_id;
    >> + struct device_node *np = pdev->dev.of_node;
    >> +
    >> + /* no device tree device */
    >> + if (!np)
    >> + return -ENODEV;
    > This breaks non-DT users. Is this what you intend? It creates a flag day
    > where users have to switch from non-DT to DT cold-turkey.

    Not supporting non-DT user was not the idea - it just simplifies the code a bit
    given that it would only even be runtime used in a ARC Linux port based platform -
    which unconditionally enables OF. Further - the ARC port itself is not yet
    upstream so there are no "official" user of this in tree driver.
    FWIW, ARC Linux port was recently reviewed on lkml/arch mailing lists and is now
    in linux-next for a possible 3.9 merge.

    >> + dev_id = of_alias_get_id(np, "serial");
    >> + if (dev_id < 0) {
    >> + dev_err(&pdev->dev, "failed to get alias id: %d\n", dev_id);
    >> + return dev_id;
    >> + }
    > Don't fail on this. If you can't get an id then choose one dynamically.

    You mean just assume 0.

    Thanks for reviewing.
    -Vineet


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