On Sat, Jul 19 2025 12:39:45 -0500, Mario Limonciello wrote: > On 7/19/25 10:25 AM, Mario Limonciello wrote: > > > > > > On 7/18/25 9:12 PM, Lauri Tirkkonen wrote: > > > On Fri, Jul 18 2025 20:14:08 -0500, Mario Limonciello wrote: > > > > OK, I think we need to do two things to figure out what's going on. > > > > > > > > 1) Let's shift over to 6.16-rc6. Once we've got a handle on the > > > > situation > > > > there we can iron out if there are other patches missing or this is also > > > > broken for you in 6.16. If it's not working as expected there either we > > > > need it fixed there first anyway. > > > > > > Same behavior on 6.16-rc6: brightness is set to 0 (max 399000), > > > minimally visible. > > > > > > > 2) The starting brightness I don't expect to be "0". We need to > > > > see what > > > > values were read out from the firmware. There is a debugging > > > > message we can > > > > catch if you boot with drm.debug=0x106. Keep in mind you > > > > probably need to > > > > increase log_buf_len if your ring buffer is set too small too. > > > > > > > > https://github.com/torvalds/linux/ > > > > commit/4b61b8a390511a1864f26cc42bab72881e93468d > > > > > > > > PS: I would rather you add logs into a gist, pastebin or a bug > > > > somewhere if > > > > you can. > > > > > > [ 3.210757] amdgpu 0000:03:00.0: > > > [drm:amdgpu_dm_connector_late_register [amdgpu]] Backlight caps: > > > min: 1000, max: 400000, ac 100, dc 32 > > > > > > full dmesg: https://termbin.com/o2q3 > > > > > > > Thanks for sharing. Can you get me an updated output with > > drm.debug=0x106 set and with this applied? I want to see what values > > were set. > > > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/ > > drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > > index 5df7f8c34231..cdc43cfb39dd 100644 > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > > @@ -10489,8 +10489,12 @@ static void amdgpu_dm_atomic_commit_tail(struct > > drm_atomic_state *state) > > /* restore the backlight level */ > > for (i = 0; i < dm->num_of_edps; i++) { > > if (dm->backlight_dev[i] && > > - (dm->actual_brightness[i] != dm->brightness[i])) > > + (dm->actual_brightness[i] != dm->brightness[i])) { > > + drm_WARN(adev_to_drm(adev), true, > > + "Backlight level %d does not > > match actual brightness %d for edp %d\n", > > + dm->brightness[i], dm- > > >actual_brightness[i], i); > > amdgpu_dm_backlight_set_level(dm, i, dm- > > >brightness[i]); > > + } > > } > > > > /* > > > > Also, does turning off custom brightness curves > > (amdgpu.dcdebugmask=0x40000) help? > > > > In advance of getting that updated log; I have a theory what's going on. I > think the first value programmed to brightness happens as part of that very > first modeset. > > If that's what's going on, then I think doing an explicit programming cycle > at the backlight registration will help. Here's a potential patch. > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > index b19e7964060d..4b99efbaf481 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > @@ -4996,6 +4996,8 @@ amdgpu_dm_register_backlight_device(struct > amdgpu_dm_connector *aconnector) > dm->backlight_dev[aconnector->bl_idx] = NULL; > } else > drm_dbg_driver(drm, "DM: Registered Backlight device: %s\n", > bl_name); > + > + amdgpu_dm_backlight_update_status(dm->backlight_dev[aconnector->bl_idx]); > } > > static int initialize_plane(struct amdgpu_display_manager *dm,
This patch was malformed, so I applied it manually. It didn't help though - brightness still zero. I came up with a patch that does help; will post in this thread shortly. -- Lauri Tirkkonen | lotheac @ IRCnet
