Hi Thorsten,

[Lothar Rubusch]

On Mon, Feb 16, 2026 at 8:46 AM Thorsten Blum <thorsten.blum@xxxxxxxxx> wrote:
>
> Fix otp_show() to read and print all 64 bytes of the OTP zone.
> Previously, the loop only printed half of the OTP (32 bytes), and
> partial output was returned on read errors.
>
> Propagate the actual error from atmel_sha204a_otp_read() instead of
> producing partial output.
>
> Replace sprintf() with sysfs_emit_at(), which is preferred for
> formatting sysfs output because it provides safer bounds checking.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 13909a0c8897 ("crypto: atmel-sha204a - provide the otp content")
> Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxx>
> ---
> Compile-tested only.
>
> Changes in v2:
> - Return the total number of bytes written by sysfs_emit_at() after
>   feedback from Lothar (thanks!)
> - Link to v1: https://lore.kernel.org/lkml/20260215124125.465162-2-thorsten.blum@xxxxxxxxx/
> ---
>  drivers/crypto/atmel-sha204a.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c
> index 0fcf4a39de27..8af767f903ea 100644
> --- a/drivers/crypto/atmel-sha204a.c
> +++ b/drivers/crypto/atmel-sha204a.c
> @@ -15,6 +15,7 @@
>  #include <linux/module.h>
>  #include <linux/scatterlist.h>
>  #include <linux/slab.h>
> +#include <linux/sysfs.h>
>  #include <linux/workqueue.h>
>  #include "atmel-i2c.h"
>
> @@ -119,21 +120,22 @@ static ssize_t otp_show(struct device *dev,
>  {
>         u16 addr;
>         u8 otp[OTP_ZONE_SIZE];
> -       char *str = buf;
>         struct i2c_client *client = to_i2c_client(dev);
> -       int i;
> +       ssize_t len = 0;
> +       int i, ret;
>
> -       for (addr = 0; addr < OTP_ZONE_SIZE/4; addr++) {
> -               if (atmel_sha204a_otp_read(client, addr, otp + addr * 4) < 0) {
> +       for (addr = 0; addr < OTP_ZONE_SIZE / 4; addr++) {
> +               ret = atmel_sha204a_otp_read(client, addr, otp + addr * 4);
> +               if (ret < 0) {
>                         dev_err(dev, "failed to read otp zone\n");
> -                       break;
> +                       return ret;
>                 }
>         }
>
> -       for (i = 0; i < addr*2; i++)
> -               str += sprintf(str, "%02X", otp[i]);
> -       str += sprintf(str, "\n");
> -       return str - buf;
> +       for (i = 0; i < OTP_ZONE_SIZE; i++)
> +               len += sysfs_emit_at(buf, len, "%02X", otp[i]);
> +       len += sysfs_emit_at(buf, len, "\n");
> +       return len;
>  }
>  static DEVICE_ATTR_RO(otp);
>
> --
> Thorsten Blum <thorsten.blum@xxxxxxxxx>
> GPG: 1D60 735E 8AEF 3BE4 73B6  9D84 7336 78FD 8DFE EAD4
>

I took the patch as of link below. I verified on the before described setup.
https://lore.kernel.org/lkml/20260216074552.656814-1-thorsten.blum@xxxxxxxxx/

worked, LGTM

Reviewed-by: Lothar Rubusch <l.rubusch@xxxxxxxxx>

Best,
L