2 Commits

Author	SHA1	Message	Date
Simon Rettberg	5954acbacb	drm/display: Don't assume dual mode adaptors support i2c sub-addressing ... Current dual mode adaptor ("DP++") detection code assumes that all adaptors support i2c sub-addressing for read operations from the DP-HDMI adaptor ID buffer. It has been observed that multiple adaptors do not in fact support this, and always return data starting at register 0. On affected adaptors, the code fails to read the proper registers that would identify the device as a type 2 adaptor, and handles those as type 1, limiting the TMDS clock to 165MHz, even if the according register would announce a higher TMDS clock. Fix this by always reading the ID buffer starting from offset 0, and discarding any bytes before the actual offset of interest. We tried finding authoritative documentation on whether or not this is allowed behaviour, but since all the official VESA docs are paywalled, the best we could come up with was the spec sheet for Texas Instruments' SNx5DP149 chip family.[1] It explicitly mentions that sub-addressing is supported for register writes, but *not* for reads (See NOTE in section 8.5.3). Unless TI openly decided to violate the VESA spec, one could take that as a hint that sub-addressing is in fact not mandated by VESA. The other two adaptors affected used the PS8409(A) and the LT8611, according to the data returned from their ID buffers. [1] https://www.ti.com/lit/ds/symlink/sn75dp149.pdf Cc: stable@vger.kernel.org Signed-off-by: Simon Rettberg <simon.rettberg@rz.uni-freiburg.de> Reviewed-by: Rafael Gieschke <rafael.gieschke@rz.uni-freiburg.de> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20221006113314.41101987@computer Acked-by: Jani Nikula <jani.nikula@intel.com>	2022-11-15 23:31:02 +02:00
Thomas Zimmermann	da68386d9e	drm: Rename dp/ to display/ ... Rename dp/ to display/ to account for additional display-related helpers, such as HDMI. Update all related include statements. No functional changes. Various drivers, such as i915 and amdgpu, use similar naming scheme by putting code for video-output standards into a local display/ directory. The new directory's name is aligned with this convention. v2: * update commit message (Javier) Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Reviewed-by: Lyude Paul <lyude@redhat.com> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220421073108.19226-3-tzimmermann@suse.de	2022-04-25 11:17:45 +02:00