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    SubjectRe: [PATCH] mtd: nand: raw: atmel: add module param to avoid using dma
    On Thu, 29 Mar 2018 15:10:54 +0200
    Peter Rosin <peda@axentia.se> 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>

    Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>

    Miquel, can you queue this one to nand/next.

    > ---
    > 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);
    > +
    > enum atmel_nand_rb_type {
    > ATMEL_NAND_NO_RB,
    > ATMEL_NAND_NATIVE_RB,
    > @@ -1977,7 +1982,7 @@ static int atmel_nand_controller_init(struct atmel_nand_controller *nc,
    > return ret;
    > }
    >
    > - if (nc->caps->has_dma) {
    > + if (nc->caps->has_dma && !atmel_nand_avoid_dma) {
    > dma_cap_mask_t mask;
    >
    > dma_cap_zero(mask);

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