AuxXxilium/linux_dsm_epyc7002
1
0
Fork 0
mirror of https://github.com/AuxXxilium/linux_dsm_epyc7002.git synced 2024-12-28 11:18:45 +07:00
Code Issues Actions Packages Projects Releases Wiki Activity

drm/vc4: kms: Document the muxing corner cases

Browse Source 
We've had a number of muxing corner-cases with specific ways to reproduce
them, so let's document them to make sure they aren't lost and introduce
regressions later on.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Reviewed-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20201105135656.383350-6-maxime@cerno.tech
This commit is contained in:
Maxime Ripard 2020-11-05 14:56:54 +01:00
parent a72b0458cd
commit b5dbc4d368
No known key found for this signature in database
GPG Key ID: E3EF0D6F671851C5
1 changed files with 22 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
drivers/gpu/drm/vc4/vc4_kms.c
View File

@ -662,6 +662,28 @@ static int vc4_load_tracker_obj_init(struct vc4_dev *vc4)
return drmm_add_action_or_reset(&vc4->base, vc4_load_tracker_obj_fini, NULL);
}
/*
* The BCM2711 HVS has up to 7 outputs connected to the pixelvalves and
* the TXP (and therefore all the CRTCs found on that platform).
*
* The naive (and our initial) implementation would just iterate over
* all the active CRTCs, try to find a suitable FIFO, and then remove it
* from the pool of available FIFOs. However, there are a few corner
* cases that need to be considered:
*
* - When running in a dual-display setup (so with two CRTCs involved),
* we can update the state of a single CRTC (for example by changing
* its mode using xrandr under X11) without affecting the other. In
* this case, the other CRTC wouldn't be in the state at all, so we
* need to consider all the running CRTCs in the DRM device to assign
* a FIFO, not just the one in the state.
*
* - Since we need the pixelvalve to be disabled and enabled back when
* the FIFO is changed, we should keep the FIFO assigned for as long
* as the CRTC is enabled, only considering it free again once that
* CRTC has been disabled. This can be tested by booting X11 on a
* single display, and changing the resolution down and then back up.
*/
static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
struct drm_atomic_state *state)
{