mtd: rawnand: brcmnand: skip DMA during panic write

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

Posted by Kamal Dasu 1 month ago

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@broadcom.com>
---
 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

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

Posted by Miquel Raynal 4 weeks, 1 day ago

On Thu, 05 Mar 2026 15:21:57 -0500, Kamal Dasu 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.
> 
> 
> [...]

Applied to mtd/fixes, thanks!

[1/1] mtd: rawnand: brcmnand: skip DMA during panic write
      commit: da9ba4dcc01e7cf52b7676f0ee9607b8358c2171

Patche(s) should be available on mtd/linux.git and will be
part of the next PR (provided that no robot complains by then).

Kind regards,
Miquèl

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

Posted by William Zhang 1 month ago

On Thu, Mar 5, 2026 at 12:23 PM Kamal Dasu <kamal.dasu@broadcom.com> 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@broadcom.com>
> ---
>  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@broadcom.com>

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

Posted by Florian Fainelli 1 month ago

On 3/5/26 12:21, Kamal Dasu 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@broadcom.com>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian