On Mon, 31 Aug 2026, Thomas Zimmermann <[email protected]> wrote:
> Sysfb drivers currently use the given display mode for looking up the
> panel orientation. But the look-up table stores the native geometry of
> the panels, so the lookup fails if the current mode sizes differs.
>
> Get the panel's native geometry with drm_edid_get_preferred_size() from
> the EDID and use it for looking up the panel orientation.
>
> v2:
> - ofdrm: validate EDID header before using it (Sashiko)
>
> Signed-off-by: Thomas Zimmermann <[email protected]>
> Acked-by: Ard Biesheuvel <[email protected]>
> ---
> drivers/gpu/drm/sysfb/efidrm.c | 17 ++++++++++++++++-
> drivers/gpu/drm/sysfb/ofdrm.c | 18 ++++++++++++++++--
> drivers/gpu/drm/sysfb/vesadrm.c | 17 ++++++++++++++++-
> 3 files changed, 48 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/sysfb/efidrm.c b/drivers/gpu/drm/sysfb/efidrm.c
> index 3f9cd5d03efb..7a7d12003304 100644
> --- a/drivers/gpu/drm/sysfb/efidrm.c
> +++ b/drivers/gpu/drm/sysfb/efidrm.c
> @@ -152,6 +152,7 @@ static struct efidrm_device *efidrm_device_create(struct
> drm_driver *drv,
> const struct screen_info *si;
> const struct drm_format_info *format;
> int width, height, stride;
> + unsigned int panel_width, panel_height;
> s64 vsize;
> u64 mem_flags;
> struct resource resbuf;
> @@ -217,6 +218,20 @@ static struct efidrm_device *efidrm_device_create(struct
> drm_driver *drv,
> if (drm_edid_header_is_valid(dpy->edid.dummy) == 8)
> sysfb->edid = dpy->edid.dummy;
> #endif
> +
> + panel_width = width;
> + panel_height = height;
> +
> + if (sysfb->edid) {
> + const struct drm_edid *drm_edid;
> +
> + drm_edid = drm_edid_alloc(sysfb->edid, EDID_LENGTH);
> + if (drm_edid) {
> + drm_edid_get_preferred_size(drm_edid, &panel_width,
> &panel_height);
> + drm_edid_free(drm_edid);
> + }
> + }
> +
Unrelated to the patch at hand, but does all of this code assume EDID is
always just one block? Scary. The whole sysfs->edid being a u8 pointer
without size feels like a footgun.
Here, the above should work, but I've been kind of hoping to eradicate
EDID_LENGTH assumptions and calculations from everywhere outside of
drm_edid.c, because it's complicated.
BR,
Jani.
> sysfb->fb_mode = drm_sysfb_mode(width, height, 0, 0);
> sysfb->fb_format = format;
> sysfb->fb_pitch = stride;
> @@ -340,7 +355,7 @@ static struct efidrm_device *efidrm_device_create(struct
> drm_driver *drv,
> drm_connector_helper_add(connector, &efidrm_connector_helper_funcs);
> drm_connector_set_panel_orientation_with_quirk(connector,
>
> DRM_MODE_PANEL_ORIENTATION_UNKNOWN,
> - width, height);
> + panel_width,
> panel_height);
> if (sysfb->edid)
> drm_connector_attach_edid_property(connector);
>
> diff --git a/drivers/gpu/drm/sysfb/ofdrm.c b/drivers/gpu/drm/sysfb/ofdrm.c
> index 9d60db45139c..a0a865aee098 100644
> --- a/drivers/gpu/drm/sysfb/ofdrm.c
> +++ b/drivers/gpu/drm/sysfb/ofdrm.c
> @@ -229,7 +229,7 @@ static const u8 *display_get_edid_of(struct drm_device
> *dev, struct device_node
> {
> int ret = of_property_read_u8_array(of_node, "EDID", buf, EDID_LENGTH);
>
> - if (ret)
> + if (ret || drm_edid_header_is_valid(buf) != 8)
> return NULL;
> return buf;
> }
> @@ -828,6 +828,7 @@ static struct ofdrm_device *ofdrm_device_create(struct
> drm_driver *drv,
> enum ofdrm_model model;
> bool big_endian;
> int width, height, depth, linebytes;
> + unsigned int panel_width, panel_height;
> const struct drm_format_info *format;
> u64 address;
> const u8 *edid;
> @@ -998,6 +999,19 @@ static struct ofdrm_device *ofdrm_device_create(struct
> drm_driver *drv,
> sysfb->fb_gamma_lut_size = OFDRM_GAMMA_LUT_SIZE;
> sysfb->edid = edid;
>
> + panel_width = width;
> + panel_height = height;
> +
> + if (sysfb->edid) {
> + const struct drm_edid *drm_edid;
> +
> + drm_edid = drm_edid_alloc(sysfb->edid, EDID_LENGTH);
> + if (drm_edid) {
> + drm_edid_get_preferred_size(drm_edid, &panel_width,
> &panel_height);
> + drm_edid_free(drm_edid);
> + }
> + }
> +
> drm_dbg(dev, "display mode={" DRM_MODE_FMT "}\n",
> DRM_MODE_ARG(&sysfb->fb_mode));
> drm_dbg(dev, "framebuffer format=%p4cc, size=%dx%d, linebytes=%d
> byte\n",
> &format->format, width, height, linebytes);
> @@ -1069,7 +1083,7 @@ static struct ofdrm_device *ofdrm_device_create(struct
> drm_driver *drv,
> drm_connector_helper_add(connector, &ofdrm_connector_helper_funcs);
> drm_connector_set_panel_orientation_with_quirk(connector,
>
> DRM_MODE_PANEL_ORIENTATION_UNKNOWN,
> - width, height);
> + panel_width,
> panel_height);
> if (edid)
> drm_connector_attach_edid_property(connector);
>
> diff --git a/drivers/gpu/drm/sysfb/vesadrm.c b/drivers/gpu/drm/sysfb/vesadrm.c
> index 6a67b2d2e451..8c52bbac6d2f 100644
> --- a/drivers/gpu/drm/sysfb/vesadrm.c
> +++ b/drivers/gpu/drm/sysfb/vesadrm.c
> @@ -402,6 +402,7 @@ static struct vesadrm_device
> *vesadrm_device_create(struct drm_driver *drv,
> const struct screen_info *si;
> const struct drm_format_info *format;
> int width, height, stride;
> + unsigned int panel_width, panel_height;
> s64 vsize;
> struct resource resbuf;
> struct resource *res;
> @@ -484,6 +485,20 @@ static struct vesadrm_device
> *vesadrm_device_create(struct drm_driver *drv,
> if (drm_edid_header_is_valid(dpy->edid.dummy) == 8)
> sysfb->edid = dpy->edid.dummy;
> #endif
> +
> + panel_width = width;
> + panel_height = height;
> +
> + if (sysfb->edid) {
> + const struct drm_edid *drm_edid;
> +
> + drm_edid = drm_edid_alloc(sysfb->edid, EDID_LENGTH);
> + if (drm_edid) {
> + drm_edid_get_preferred_size(drm_edid, &panel_width,
> &panel_height);
> + drm_edid_free(drm_edid);
> + }
> + }
> +
> sysfb->fb_mode = drm_sysfb_mode(width, height, 0, 0);
> sysfb->fb_format = format;
> sysfb->fb_pitch = stride;
> @@ -585,7 +600,7 @@ static struct vesadrm_device
> *vesadrm_device_create(struct drm_driver *drv,
> drm_connector_helper_add(connector, &vesadrm_connector_helper_funcs);
> drm_connector_set_panel_orientation_with_quirk(connector,
>
> DRM_MODE_PANEL_ORIENTATION_UNKNOWN,
> - width, height);
> + panel_width,
> panel_height);
> if (sysfb->edid)
> drm_connector_attach_edid_property(connector);
--
Jani Nikula, Intel
