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    SubjectRe: PXA2xx SPI controller updated for 2.6.16-rc1?
    On Thu, 2006-01-19 at 10:51 +0000, David Vrabel wrote:
    > Stephen,
    > Do you have a version of the PXA2xx SPI contoller driver more recent
    > that the one posted at the end of October 2005? There are some SPI (and
    > other) API changes required for 2.6.16-rc1.
    I'm working on it now. I expect to have something with in the week. I
    had some user space problems bringing up 2.6.15 which has cause some

    > I've attached my attempt (PIO works but DMA doesn't) if it's of any use.
    > The patch also:
    > - includes support for the different clock on the PXA27x
    > - calculates the correct clock divisor (at least on the PXA27x...)
    > - allows null_cs_control for PIO transfer.
    I will review and integrate you changes. THANKS!

    > I'm currently using SSP3 on the PXA27x with the slave chip select GPIO
    > line configured as SSPSFRM3 instead of a GPIO. This works fine provided
    > that each spi_message consists of a single spi_transfer. With more than
    > one transfer they're not back-to-back and SSPSFRM3 is deasserted
    > between transfers.
    I believe this is the correct SSP in SPI mode behavior for PXA2xx.

    > It looks like you're waiting for the transmit buffer in the controller
    > to empty before switching to the next transfer. Is it possible to
    > switch to the next transfer immediatly upon exhausting the transfer's
    > tx_buf? Perhaps (in the DMA case) by chaining several DMA descriptors
    > together?
    DMA descriptor chaining the next optimization for the driver. I want to
    get the driver cleaned up, tested and posted before starting this.

    > At the higher SPI clock rates available on the PXA27x (up to 13 MHz with
    > the internal clock) PIO mode doesn't seem to feed the transmit buffer
    > fast enough resulting in gaps between each byte/word of the transfer. I
    > would assume using DMA would not show this?
    Correct, I think the PXA2xx even states this in the docs.

    Thanks your input, I really appreciate it. I will send you my updates
    ASAP. Most likely a 2.6.15 version quickly follow by a 2.6.16-rc


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