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    SubjectRe: [PATCH 1/2] dmaengine: Fix status handling in imx-dma.
    On Fri, Jan 06, 2012 at 04:40:24PM +0530, Vinod Koul wrote:
    > On Fri, 2012-01-06 at 10:37 +0100, Sascha Hauer wrote:
    > > On Fri, Jan 06, 2012 at 11:26:29AM +0530, Vinod Koul wrote:
    > > > On Mon, 2012-01-02 at 13:18 +0100, Javier Martin wrote:
    > > > > Status must only be changed to DMA_IN_PROGRESS
    > > > > when the DMA transfer has really begun.
    > > > >
    > > > > However, since this driver lacks of support for
    > > > > multiple descriptors a new flag has to be introduced
    > > > > to avoid the prepare function be called multiple times.
    > > > Thanks this is the right approach to fix this driver
    > > >
    > > > But this will obviously break any users of this driver as they need to
    > > > call the right APIs now :D
    > > >
    > > > Sacha: can you check this patch and see which users of this driver will
    > > > break. we need those fixes to go along this patch as well
    > >
    > > Which users should break? I just tried with the mxcmmc driver and this
    > > one does not break.
    > >
    > > I do not really understand this patch anyway. It changes imxdmac->status
    > > to a write-only variable and introduces a imxdmac->prepared variable
    > > with the same meaning. This patch is a complicated no-op.
    > >
    > > What was the original problem? The fact that we used a enum dma_status
    > > with the wrong semantics? In that case I suggest to simply replace this
    > > variable. All we need to track is that we do not enter
    > > imxdma_prep_slave_sg with an already running transfer.
    > the memcpy patch submitted earlier didn't use correct dmaengine API. a
    > descriptor is not supposed to be started in prepare. The reason given
    > was the driver already does so for all other prepares, so i suggested to
    > fix that. Descriptors should be started in issue_pending only.

    The transfer is not started in prepare but in imxdmac->desc.tx_submit

    Sascha


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