Re: [PATCH] drm: Add drm.edid_quirk_param module parameter

From: Jani Nikula
Date: Wed Aug 15 2018 - 09:05:43 EST


On Wed, 08 Aug 2018, Keith Packard <keithp@xxxxxxxxxx> wrote:
> This parameter allows the set of EDID quirks to be changed at
> runtime. The syntax is
>
> vendor/product/quirks,vendor/product/quirks,...
>
> where vendor is the three-letter EDID vendor value, product is the
> EDID product id which may be prefixed with 0x to for hex instead of
> decimal values and quirks is the replacement quirks value from the
> list in drm_edid.c.

Why?

I guess if we want to manage quirks from userspace, we should work to
provide an interface udev can use.

BR,
Jani.

>
> Signed-off-by: Keith Packard <keithp@xxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_edid.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 5dc742b27ca0..63b4587faddd 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -98,6 +98,12 @@ struct detailed_mode_closure {
> #define LEVEL_GTF2 2
> #define LEVEL_CVT 3
>
> +#define EDID_QUIRK_PARAM_LEN 256
> +static char edid_quirk_param[EDID_QUIRK_PARAM_LEN];
> +module_param_string(edid_quirk_param, edid_quirk_param, sizeof(edid_quirk_param), 0644);
> +MODULE_PARM_DESC(edid_quirk_param, "Extra EDID quirks, "
> + "format is 'vendor/product/quirks;...' ");
> +
> static const struct edid_quirk {
> char vendor[4];
> int product_id;
> @@ -1774,8 +1780,24 @@ static bool edid_vendor(const struct edid *edid, const char *vendor)
> static u32 edid_get_quirks(const struct edid *edid)
> {
> const struct edid_quirk *quirk;
> + const char *q;
> int i;
>
> + for (q = edid_quirk_param; q && *q; q = strchr(q, ',')) {
> + char vendor[4];
> + int product_id;
> + int quirks;
> +
> + while (*q == ',')
> + q++;
> +
> + if (sscanf(q, "%3s/%i/%i", vendor, &product_id, &quirks) == 3) {
> + if (edid_vendor(edid, vendor) &&
> + (EDID_PRODUCT_ID(edid) == product_id))
> + return quirks;
> + }
> + }
> +
> for (i = 0; i < ARRAY_SIZE(edid_quirk_list); i++) {
> quirk = &edid_quirk_list[i];

--
Jani Nikula, Intel Open Source Graphics Center