On Thu, Oct 7, 2021 at 6:24 PM Stephen Boyd swboyd@chromium.org wrote:
Quoting Saravana Kannan (2021-10-07 18:10:24)
On Thu, Oct 7, 2021 at 1:11 PM Stephen Boyd swboyd@chromium.org wrote:
Quoting Stephen Boyd (2021-10-07 11:40:07)
Quoting Saravana Kannan (2021-10-06 20:07:11)
On Wed, Oct 6, 2021 at 12:38 PM Stephen Boyd swboyd@chromium.org wrote:
diff --git a/drivers/base/component.c b/drivers/base/component.c index 0a41bbe14981..d99e99cabb99 100644 --- a/drivers/base/component.c +++ b/drivers/base/component.c
[...]
continue;/* Matches put in component_del() */get_device(&adev->dev);c->link = device_link_add(&adev->dev, c->dev,DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);Remove the STATELESS flag and you'll get a bunch of other stuff done for free:
I tried that and it didn't work for me. The aggregate device never probed and I was left with no display. Let me see if I can reproduce it with logging to provide more details.
This patch fixes it (whitespace damaged sorry).
Not sure why you have to trigger an explicit rescan, but instead of this patch below, you could also try setting this flag instead? DL_FLAG_AUTOPROBE_CONSUMER
I'd rather not conflate component driver probe with component_add() being called. It's simpler if that is the case, i.e. all component drivers are calling component_add() in their driver probe routine, but I don't know if that's always true. I did this poor audit of the kernel
$ git grep -p [^_]component_add | grep .c= | grep -v probe drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c=static int amdgpu_dm_audio_init(struct amdgpu_device *adev) drivers/gpu/drm/i915/display/intel_audio.c=static void i915_audio_component_init(struct drm_i915_private *dev_priv) drivers/gpu/drm/i915/display/intel_hdcp.c=void intel_hdcp_component_init(struct drm_i915_private *dev_priv) drivers/gpu/drm/nouveau/dispnv50/disp.c=nv50_audio_component_init(struct nouveau_drm *drm) drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c=static int dw_mipi_dsi_rockchip_host_attach(void *priv_data, drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c=static int dw_mipi_dsi_dphy_init(struct phy *phy) drivers/gpu/drm/vc4/vc4_dsi.c=static int vc4_dsi_host_attach(struct mipi_dsi_host *host,
and then peeking at rockchip above I see that component_add() is called in the mipi dsi attach ops and then I got lost trying to figure out where it ends up. Maybe it is still in some probe call?
Anyway, I think we still have to do a rescan so that we can try to bind the aggregate device. Is there a better API to use for that?
If you know the exact device, you could call device_attach()? That's what bus_rescan_devices() eventually calls, but you skip the unnecessary looping over all the other devices.
-Saravana