Re: [PATCH] mtd: rawnand: brcmnand: skip DMA during panic write

[William Zhang]

On Thu, Mar 5, 2026 at 12:23 PM Kamal Dasu <kamal.dasu@xxxxxxxxxxxx> wrote:
>
> When oops_panic_write is set, the driver disables interrupts and
> switches to PIO polling mode but still falls through into the DMA
> path. DMA cannot be used reliably in panic context, so make the
> DMA path an else branch to ensure only PIO is used during panic
> writes.
>
> Fixes: c1ac2dc34b51 ("mtd: rawnand: brcmnand: When oops in progress use pio and interrupt polling")
> Signed-off-by: Kamal Dasu <kamal.dasu@xxxxxxxxxxxx>
> ---
>  drivers/mtd/nand/raw/brcmnand/brcmnand.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> index 0427d76f45d0..5b9dadd5405e 100644
> --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> @@ -2350,14 +2350,12 @@ static int brcmnand_write(struct mtd_info *mtd, struct nand_chip *chip,
>         for (i = 0; i < ctrl->max_oob; i += 4)
>                 oob_reg_write(ctrl, i, 0xffffffff);
>
> -       if (mtd->oops_panic_write)
> +       if (mtd->oops_panic_write) {
>                 /* switch to interrupt polling and PIO mode */
>                 disable_ctrl_irqs(ctrl);
> -
> -       if (use_dma(ctrl) && (has_edu(ctrl) || !oob) && flash_dma_buf_ok(buf)) {
> +       } else if (use_dma(ctrl) && (has_edu(ctrl) || !oob) && flash_dma_buf_ok(buf)) {
>                 if (ctrl->dma_trans(host, addr, (u32 *)buf, oob, mtd->writesize,
>                                     CMD_PROGRAM_PAGE))
> -
>                         ret = -EIO;
>
>                 goto out;
> --
> 2.34.1
>

Reviewed-by: William Zhang <william.zhang@xxxxxxxxxxxx>