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    SubjectRe: [PATCH] mtd: nand: raw: atmel: add module param to avoid using dma
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    On 2018-03-29 16:20, Nicolas Ferre wrote:
    > On 29/03/2018 at 15:10, Peter Rosin wrote:
    >> On a sama5d31 with a Full-HD dual LVDS panel (132MHz pixel clock) NAND
    >> flash accesses have a tendency to cause display disturbances. Add a
    >> module param to disable DMA from the NAND controller, since that fixes
    >> the display problem for me.
    >>
    >> Signed-off-by: Peter Rosin <peda@axentia.se>
    >> ---
    >> drivers/mtd/nand/raw/atmel/nand-controller.c | 7 ++++++-
    >> 1 file changed, 6 insertions(+), 1 deletion(-)
    >>
    >> diff --git a/drivers/mtd/nand/raw/atmel/nand-controller.c b/drivers/mtd/nand/raw/atmel/nand-controller.c
    >> index b2f00b398490..2ff7a77c7b8e 100644
    >> --- a/drivers/mtd/nand/raw/atmel/nand-controller.c
    >> +++ b/drivers/mtd/nand/raw/atmel/nand-controller.c
    >> @@ -129,6 +129,11 @@
    >> #define DEFAULT_TIMEOUT_MS 1000
    >> #define MIN_DMA_LEN 128
    >>
    >> +static bool atmel_nand_avoid_dma __read_mostly;
    >> +
    >> +MODULE_PARM_DESC(avoiddma, "Avoid using DMA");
    >> +module_param_named(avoiddma, atmel_nand_avoid_dma, bool, 0400);
    >
    > We had the DT parameter "atmel,nand-has-dma" for this purpose and it was
    > associated with a module parameter as well (use_dma,).
    >
    > Is it only managed by old DT binding?

    Saw it, but I need the reverse. I.e. *not* using DMA.

    And I didn't think this belonged in DT since in some sense it doesn't really
    describe HW so I went with a module parameter.

    Cheers,
    Peter

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