Re: [PATCH 2/2] drm/panic: Accept a trailing newline in panic_screen

[Tvrtko Ursulin]

On 16/10/2026 06:27, Devin Wittmayer wrote:
> Setting the panic screen through sysfs with echo fails with EINVAL,
> because the value ends in a newline. Ignore it when matching.
>
> Fixes: e85e9ccf3f84 ("drm/panic: Report invalid or unsupported panic modes")
> Signed-off-by: Devin Wittmayer <lucid_duck@xxxxxxxxxxxxx>
> ---
> QEMU, 10 runs each, on drm-misc-fixes and drm-misc-next:
>
>                                       before    after
>    write of "user\n"                  refused   takes
>    write of "bsod\n"                  refused   refused

Hah funny, becuase before e85e9ccf3f84 it used to take "bsod\n" but 
AFAIR it would silently revert to displaying "user". Because old code 
was this:

static void draw_panic_dispatch(struct drm_scanout_buffer *sb)
{
       if (!strcmp(drm_panic_screen, "kmsg")) {
               draw_panic_static_kmsg(sb);
       } else if (!strcmp(drm_panic_screen, "qr_code")) {
               draw_panic_static_qr_code(sb);
       } else {
               draw_panic_static_user(sb);
       }
}

But it is true that it would also silently accept "user\n" so I guess 
you can call it a partial regression.

Anyway, the fix LGTM.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>

Regards,

Tvrtko

>    drm.panic_screen=user at boot      takes     takes
>
> amdgpu, 2 runs each, 7.2.6 with Arch's source and config:
>
>    echo user                          refused   takes
>
>   drivers/gpu/drm/drm_panic.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
> index 29b1487de7ae0..7847b38ba9aab 100644
> --- a/drivers/gpu/drm/drm_panic.c
> +++ b/drivers/gpu/drm/drm_panic.c
> @@ -839,7 +839,7 @@ static int drm_panic_type_set(const char *val, const struct kernel_param *kp)
>   	unsigned int i;
>   
>   	for (i = 0; i < ARRAY_SIZE(drm_panic_type_map); i++) {
> -		if (!strcmp(val, drm_panic_type_map[i])) {
> +		if (sysfs_streq(val, drm_panic_type_map[i])) {
>   			drm_panic_type = i;
>   			return 0;
>   		}