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    SubjectRe: [PATCH 6/6] dma/imx-sdma: check whether event_id0 < 32 when set event_mask
    On Wed, Jan 11, 2012 at 08:53:23AM +0800, Richard Zhao wrote:
    > On Tue, Jan 10, 2012 at 11:38:39PM +0800, Shawn Guo wrote:
    > > On Tue, Jan 10, 2012 at 10:29:42PM +0800, Richard Zhao wrote:
    > > > On Tue, Jan 10, 2012 at 10:20:10PM +0800, Shawn Guo wrote:
    > > > > On Tue, Jan 10, 2012 at 03:01:50PM +0800, Richard Zhao wrote:
    > > > > > Signed-off-by: Richard Zhao <richard.zhao@linaro.org>
    > > > > > ---
    > > > >
    > > > > I think it deserves a sensible commit message explaining why the patch
    > > > > is needed.
    > > > If event_id0 < 32, 1 << (sdmac->event_id0 - 32) is not zero.
    > This meant to make you clear about the patch. I'll add it in commit
    > message.
    unsigned int t = 31;
    printf("%d %08x\n", t, 1 << (t-32));

    I test above code on both x86 and arm. They shows different results.
    x86: 31 80000000
    arm: 31 00000000

    I think we still need this patch. we shoud not let it depends on gcc's
    behavior.

    Thanks
    Richard
    > > >
    > > My point is you may explain the exact problem you are seeing without
    > > this patch
    > The kernel don't have event_id < 32 case yet. I found the bug when
    > I review the code.
    > > and how the patch helps here. In general, doing so would
    > > win a warm feeling from reviewers much more easily than leaving the
    > > commit message empty there.
    > I understand your point that comment as much as possible.
    >
    > Thanks
    > Richard
    > >
    > > --
    > > Regards,
    > > Shawn
    > >
    > > _______________________________________________
    > > linux-arm-kernel mailing list
    > > linux-arm-kernel@lists.infradead.org
    > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
    > >
    >
    >
    > _______________________________________________
    > linux-arm-kernel mailing list
    > linux-arm-kernel@lists.infradead.org
    > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
    >



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