[PATCH v2] mtd: nand: cadence: Fix device assignment to avoid warm reset issue

[Michael Nazzareno Trimarchi]

Hi Dinesh

Please adjust your signature seems that intel.com domain is not valid

MIchael

On Tue, Aug 19, 2025 at 10:23 AM Michael Nazzareno Trimarchi <
michael at amarulasolutions.com> wrote:

>
>
> On Tue, Aug 19, 2025 at 9:16 AM <dinesh.maniyam at altera.com> wrote:
>
>> From: Dinesh Maniyam <dinesh.maniyam at intel.com>
>>
>> The driver currently does:
>>     mtd->dev->parent = cadence->dev;
>>
>> This works in Linux because `struct mtd_info` embeds a `struct device`,
>> so `mtd->dev` is always valid and its `.parent` can be set.
>>
>> In U-Boot, however, `mtd->dev` is only a pointer to a `struct udevice`.
>> Dereferencing it before assignment is invalid, which breaks the device
>> hierarchy. As a result, consumers relying on `mtd->dev` (e.g. partition
>> parser, reset and re-init paths) operate on a dangling pointer. This
>> leads to failures during warm reset when the NAND device is accessed
>> again.
>>
>> Fix by assigning the device pointer directly:
>>     mtd->dev = cadence->dev;
>>
>> This matches U-Boot’s device model, preserves a valid hierarchy, and
>> resolves the warm reset issue on Cadence NAND.
>>
>> Fixes: ebc41cad ("drivers: mtd: nand: Add driver for Cadence Nand")
>> Signed-off-by: Dinesh Maniyam <dinesh.maniyam at intel.com>
>> ---
>>
>
> Reviewed-by: Michael Trimarchi <michael at amarulasolutions.com>
>
>
>>  drivers/mtd/nand/raw/cadence_nand.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/mtd/nand/raw/cadence_nand.c
>> b/drivers/mtd/nand/raw/cadence_nand.c
>> index 27aa7f97a45..4771440d1de 100644
>> --- a/drivers/mtd/nand/raw/cadence_nand.c
>> +++ b/drivers/mtd/nand/raw/cadence_nand.c
>> @@ -2196,7 +2196,7 @@ static int cadence_nand_chip_init(struct
>> cadence_nand_info *cadence, ofnode node
>>         chip->controller = &cadence->controller;
>>         nand_set_flash_node(chip, node);
>>         mtd = nand_to_mtd(chip);
>> -       mtd->dev->parent = cadence->dev;
>> +       mtd->dev = cadence->dev;
>>
>>         chip->options |= NAND_BUSWIDTH_AUTO;
>>         chip->select_chip = cadence_nand_select_chip;
>> --
>> 2.35.3
>>
>>
>
> --
> Michael Nazzareno Trimarchi
> Co-Founder & Chief Executive Officer
> M. +39 347 913 2170
> michael at amarulasolutions.com
> __________________________________
>
> Amarula Solutions BV
> Joop Geesinkweg 125, 1114 AB, Amsterdam, NL
> T. +31 (0)85 111 9172
> info at amarulasolutions.com
> www.amarulasolutions.com
>


-- 
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael at amarulasolutions.com
__________________________________

Amarula Solutions BV
Joop Geesinkweg 125, 1114 AB, Amsterdam, NL
T. +31 (0)85 111 9172
info at amarulasolutions.com
www.amarulasolutions.com