• Noralf Trønnes's avatar
    drm: Add GUD USB Display driver · 40e1a70b
    Noralf Trønnes authored
    This adds a USB display driver with the intention that it can be
    used with future USB interfaced low end displays/adapters. The Linux
    gadget device driver will serve as the canonical device implementation.
    
    The following DRM properties are supported:
    - Plane rotation
    - Connector TV properties
    
    There is also support for backlight brightness exposed as a backlight
    device.
    
    Display modes can be made available to the host driver either as DRM
    display modes or through EDID. If both are present, EDID is just passed
    on to userspace.
    
    Performance is preferred over color depth, so if the device supports
    RGB565, DRM_CAP_DUMB_PREFERRED_DEPTH will return 16.
    
    If the device transfer buffer can't fit an uncompressed framebuffer
    update, the update is split up into parts that do fit.
    
    Optimal user experience is achieved by providing damage reports either by
    setting FB_DAMAGE_CLIPS on pageflips or calling DRM_IOCTL_MODE_DIRTYFB.
    
    LZ4 compression is used if the device supports it.
    
    The driver supports a one bit monochrome transfer format: R1. This is not
    implemented in the gadget driver. It is added in preparation for future
    monochrome e-ink displays.
    
    The driver is MIT licensed to smooth the path for any BSD port of the
    driver.
    
    v2:
    - Use devm_drm_dev_alloc() and drmm_mode_config_init()
    - drm_fbdev_generic_setup: Use preferred_bpp=0, 16 was a copy paste error
    - The drm_backlight_helper is dropped, copy in the code
    - Support protocol version backwards compatibility for device
    
    v3:
    - Use donated Openmoko USB pid
    - Use direct compression from framebuffer when pitch matches, not only on
      full frames, so split updates can benefit
    - Use __le16 in struct gud_drm_req_get_connector_status
    - Set edid property when the device only provides edid
    - Clear compression fields in struct gud_drm_req_set_buffer
    - Fix protocol version negotiation
    - Remove mode->vrefresh, it's calculated
    
    v4:
    - Drop the status req polling which was a workaround for something that
      turned out to be a dwc2 udc driver problem
    - Add a flag for the Linux gadget to require a status request on
      SET operations. Other devices will only get status req on STALL errors
    - Use protocol specific error codes (Peter)
    - Add a flag for devices that want to receive the entire framebuffer on
      each flush (Lubomir)
    - Retry a failed framebuffer flush
    - If mode has changed wait for worker and clear pending damage before
      queuing up new damage, fb width/height might have changed
    - Increase error counter on bulk transfer failures
    - Use DRM_MODE_CONNECTOR_USB
    - Handle R1 kmalloc error (Peter)
    - Don't try and replicate the USB get descriptor request standard for the
      display descriptor (Peter)
    - Make max_buffer_size optional (Peter), drop the pow2 requirement since
      it's not necessary anymore.
    - Don't pre-alloc a control request buffer, it was only 4k
    - Let gud.h describe the whole protocol explicitly and don't let DRM
      leak into it (Peter)
    - Drop display mode .hskew and .vscan from the protocol
    - Shorten names: s/GUD_DRM_/GUD_/ s/gud_drm_/gud_/ (Peter)
    - Fix gud_pipe_check() connector picking when switching connector
    - Drop gud_drm_driver_gem_create_object() cached is default now
    - Retrieve USB device from struct drm_device.dev instead of keeping a
      pointer
    - Honour fb->offsets[0]
    - Fix mode fetching when connector status is forced
    - Check EDID length reported by the device
    - Use drm_do_get_edid() so userspace can overrride EDID
    - Set epoch counter to signal connector status change
    - gud_drm_driver can be const now
    
    v5:
    - GUD_DRM_FORMAT_R1: Use non-human ascii values (Daniel)
    - Change name to: GUD USB Display (Thomas, Simon)
    - Change one __u32 -> __le32 in protocol header
    - Always log fb flush errors, unless the previous one failed
    - Run backlight update in a worker to avoid upsetting lockdep (Daniel)
    - Drop backlight_ops.get_brightness, there's no readback from the device
      so it doesn't really add anything.
    - Set dma mask, needed by dma-buf importers
    
    v6:
    - Use obj-y in Makefile (Peter)
    - Fix missing le32_to_cpu() when using GUD_DISPLAY_MAGIC (Peter)
    - Set initial brightness on backlight device
    
    v7:
    - LZ4_compress_default() can return zero, check for that
    - Fix memory leak in gud_pipe_check() error path (Peter)
    - Improve debug and error messages (Peter)
    - Don't pass length in protocol structs (Peter)
    - Pass USB interface to gud_usb_control_msg() et al. (Peter)
    - Improve gud_connector_fill_properties() (Peter)
    - Add GUD_PIXEL_FORMAT_RGB111 (Peter)
    - Remove GUD_REQ_SET_VERSION (Peter)
    - Fix DRM_IOCTL_MODE_OBJ_SETPROPERTY and the rotation property
    - Fix dma-buf import (Thomas)
    
    v8:
    - Forgot to filter RGB111 from reaching userspace
    - Handle a device that only returns unknown device properties (Peter)
    - s/GUD_PIXEL_FORMAT_RGB111/GUD_PIXEL_FORMAT_XRGB1111/ (Peter)
    - Fix R1 and XRGB1111 format conversion
    - Add FIXME about Big Endian being broken (Peter, Ilia)
    
    Cc: Lubomir Rintel <lkundrak@v3.sk>
    Acked-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
    Reviewed-by: default avatarPeter Stuge <peter@stuge.se>
    Tested-by: default avatarPeter Stuge <peter@stuge.se>
    Signed-off-by: default avatarNoralf Trønnes <noralf@tronnes.org>
    Link: https://patchwork.freedesktop.org/patch/msgid/20210313112545.37527-4-noralf@tronnes.org
    40e1a70b
Makefile 4.61 KB