Re: [PATCH] dmioem: Decode Dell-specific DMI type 178

[Jean Delvare]

Hi Armin,

On Wed,  2 Oct 2024 17:02:06 +0200, Armin Wolf wrote:
> OEM DMI type 178 is used by the dell-wmi-base driver to translate
> WMI event scancodes into hotkey events. Include the available
> information in the output of dmidecode.
> 
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> ---
>  dmioem.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/dmioem.c b/dmioem.c
> index 964f287..f6ade2f 100644
> --- a/dmioem.c
> +++ b/dmioem.c
> @@ -144,6 +144,21 @@ static void dmi_dell_bios_flags(u64 flags)
>       pr_attr("ACPI WMI Supported", "%s", (flags.l & (1 << 1)) ? "Yes" : 
> "No");
>  }
> 
> +static void dmi_dell_hotkeys(const struct dmi_header *h)
> +{
> +     int count = (h->length - 0x04) / 0x04;
> +     u8 *hotkey;


Looks good to me. I would only suggest taking a quick exit here if
count is 0, so as to never print an empty list.
> +
> +     pr_list_start("Hotkey Mappings", NULL);
> +     for (int i = 0; i < count; i++)
> +     {
> +             hotkey = h->data + 0x04 + 0x04 * i;

You could also initialize hotkey to h->data + 0x04 before the loop, and
do hotkey += 0x04 after every iteration. This saves a multiplication
and an addition per iteration, so should be slightly faster.

> +             pr_list_item("Scancode 0x%04hx -> Keycode 0x%04hx",
> +                          WORD(hotkey + 0x00), WORD(hotkey + 0x02));
> +     }
> +     pr_list_end();
> +}
> +
>  static void dmi_dell_indexed_io_access(const struct dmi_header *h)
>  {
>       static const char *checksum_types[] = {
> @@ -225,6 +240,11 @@ static int dmi_decode_dell(const struct dmi_header *h)
>                       dmi_dell_bios_flags(QWORD(data + 0x04));
>                       break;
> 
> +             case 178:
> +                     pr_handle_name("Dell Hotkeys");
> +                     dmi_dell_hotkeys(h);
> +                     break;
> +
>               case 212:
>                       pr_handle_name("Dell Indexed I/O Access");
>                       if (h->length < 0x0C) break;

Thanks,
-- 
Jean Delvare
SUSE L3 Support