On Fri, 2020-09-04 at 14:53 +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> The downstream facing port caps in the DPCD can give us a hint
> as to what kind of display mode the sink can use if it doesn't
> have an EDID. Use that information to pick a suitable mode.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_helper.c | 54 +++++++++++++++++++++++++++++++++
> drivers/gpu/drm/drm_edid.c | 19 ++++++++++++
> include/drm/drm_dp_helper.h | 12 ++++++++
> include/drm/drm_edid.h | 4 +++
> 4 files changed, 89 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c
> b/drivers/gpu/drm/drm_dp_helper.c
> index f567428f2aef..0d5e9bcf11d0 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -808,6 +808,60 @@ int drm_dp_downstream_max_bpc(const u8
> dpcd[DP_RECEIVER_CAP_SIZE],
> }
> EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
>
> +/**
> + * drm_dp_downstream_mode() - return a mode for downstream facing port
> + * @dpcd: DisplayPort configuration data
> + * @port_cap: port capabilities
> + *
> + * Provides a suitable mode for downstream facing ports without EDID.
> + *
> + * Returns a new drm_display_mode on success or NULL on failure
> + */
> +struct drm_display_mode *
> +drm_dp_downstream_mode(struct drm_device *dev,
> + const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> + const u8 port_cap[4])
> +
> +{
> + u8 vic;
> +
> + if (!drm_dp_is_branch(dpcd))
> + return NULL;
> +
> + if (dpcd[DP_DPCD_REV] < 0x11)
> + return NULL;
> +
> + switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
> + case DP_DS_PORT_TYPE_NON_EDID:
> + switch (port_cap[0] & DP_DS_NON_EDID_MASK) {
> + case DP_DS_NON_EDID_720x480i_60:
> + vic = 6;
> + break;
> + case DP_DS_NON_EDID_720x480i_50:
> + vic = 21;
> + break;
> + case DP_DS_NON_EDID_1920x1080i_60:
> + vic = 5;
> + break;
> + case DP_DS_NON_EDID_1920x1080i_50:
> + vic = 20;
> + break;
> + case DP_DS_NON_EDID_1280x720_60:
> + vic = 4;
> + break;
> + case DP_DS_NON_EDID_1280x720_50:
> + vic = 19;
> + break;
> + default:
> + return NULL;
> + }
> + return drm_display_mode_from_cea_vic(dev, vic);
> + default:
> + return NULL;
> + }
> +}
> +EXPORT_SYMBOL(drm_dp_downstream_mode);
> +
> /**
> * drm_dp_downstream_id() - identify branch device
> * @aux: DisplayPort AUX channel
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 6840f0530a38..b9419fed6c28 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -3738,6 +3738,25 @@ drm_add_cmdb_modes(struct drm_connector *connector,
> u8 svd)
> bitmap_set(hdmi->y420_cmdb_modes, vic, 1);
> }
>
> +struct drm_display_mode *
> +drm_display_mode_from_cea_vic(struct drm_device *dev,
> + u8 video_code)
> +{
> + const struct drm_display_mode *cea_mode;
> + struct drm_display_mode *newmode;
> +
> + cea_mode = cea_mode_for_vic(video_code);
> + if (!cea_mode)
> + return NULL;
> +
> + newmode = drm_mode_duplicate(dev, cea_mode);
> + if (!newmode)
> + return NULL;
> +
> + return newmode;
> +}
> +EXPORT_SYMBOL(drm_display_mode_from_cea_vic);
Forgot the kdocs
> +
> static int
> do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
> {
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 6812a3e0de8d..fbba4a0f7366 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -28,6 +28,8 @@
> #include <linux/types.h>
> #include <drm/drm_connector.h>
>
> +struct drm_device;
> +
> /*
> * Unless otherwise noted, all values are from the DP 1.1a spec. Note that
> * DP and DPCD versions are independent. Differences from 1.0 are not
> noted,
> @@ -385,6 +387,13 @@
> # define DP_DS_PORT_TYPE_DP_DUALMODE 5
> # define DP_DS_PORT_TYPE_WIRELESS 6
> # define DP_DS_PORT_HPD (1 << 3)
> +# define DP_DS_NON_EDID_MASK (0xf << 4)
> +# define DP_DS_NON_EDID_720x480i_60 (1 << 4)
> +# define DP_DS_NON_EDID_720x480i_50 (2 << 4)
> +# define DP_DS_NON_EDID_1920x1080i_60 (3 << 4)
> +# define DP_DS_NON_EDID_1920x1080i_50 (4 << 4)
> +# define DP_DS_NON_EDID_1280x720_60 (5 << 4)
> +# define DP_DS_NON_EDID_1280x720_50 (7 << 4)
> /* offset 1 for VGA is maximum megapixels per second / 8 */
> /* offset 1 for DVI/HDMI is maximum TMDS clock in Mbps / 2.5 */
> /* offset 2 for VGA/DVI/HDMI */
> @@ -1654,6 +1663,9 @@ int drm_dp_downstream_min_tmds_clock(const u8
> dpcd[DP_RECEIVER_CAP_SIZE],
> int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> const u8 port_cap[4],
> const struct edid *edid);
> +struct drm_display_mode *drm_dp_downstream_mode(struct drm_device *dev,
> + const u8
> dpcd[DP_RECEIVER_CAP_SIZE],
> + const u8 port_cap[4]);
> int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]);
> void drm_dp_downstream_debug(struct seq_file *m,
> const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index cfa4f5af49af..b27a0e2169c8 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -517,4 +517,8 @@ void drm_edid_get_monitor_name(struct edid *edid, char
> *name,
> struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
> int hsize, int vsize, int fresh,
> bool rb);
> +struct drm_display_mode *
> +drm_display_mode_from_cea_vic(struct drm_device *dev,
> + u8 video_code);
> +
> #endif /* __DRM_EDID_H__ */
--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat
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