> -----Original Message-----
> From: Alex Deucher <alexdeucher@xxxxxxxxx>
> Sent: 2020/February/25, Tuesday 9:07 AM
> To: Wentland, Harry <Harry.Wentland@xxxxxxx>
> Cc: amd-gfx list <amd-gfx@xxxxxxxxxxxxxxxxxxxxx>; Maling list - DRI
> developers <dri-devel@xxxxxxxxxxxxxxxxxxxxx>; Deucher, Alexander
> <Alexander.Deucher@xxxxxxx>; Broadworth, Mark
> <Mark.Broadworth@xxxxxxx>; Liu, Zhan <Zhan.Liu@xxxxxxx>
> Subject: Re: [PATCH 13/15] drm/amdgpu/display: split dp connector
> registration (v3)
>
> On Mon, Feb 24, 2020 at 4:09 PM Harry Wentland <hwentlan@xxxxxxx>
> wrote:
> >
> > On 2020-02-07 4:17 p.m., Alex Deucher wrote:
> > > Split into init and register functions to avoid a segfault in some
> > > configs when the load/unload callbacks are removed.
> > >
> >
> > Looks like MST is completely broken with this change with a NULL
> > pointer dereference in drm_dp_aux_register.
> >
> > > v2:
> > > - add back accidently dropped has_aux setting
> > > - set dev in late_register
> > >
> > > v3:
> > > - fix dp cec ordering
> > >
> > > Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
> > > ---
> > > drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c | 16
> ++++++++++++++++
> > > drivers/gpu/drm/amd/amdgpu/atombios_dp.c | 10 ++--------
> > > .../amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 7 ++++++-
> > > 3 files changed, 24 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> > > index ec1501e3a63a..f355d9a752d2 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
> > > @@ -1461,6 +1461,20 @@ static enum drm_mode_status
> amdgpu_connector_dp_mode_valid(struct drm_connector
> > > return MODE_OK;
> > > }
> > >
> > > +static int
> > > +amdgpu_connector_late_register(struct drm_connector *connector) {
> > > + struct amdgpu_connector *amdgpu_connector =
> to_amdgpu_connector(connector);
> > > + int r = 0;
> > > +
> > > + if (amdgpu_connector->ddc_bus->has_aux) {
> > > + amdgpu_connector->ddc_bus->aux.dev = amdgpu_connector-
> >base.kdev;
> > > + r = drm_dp_aux_register(&amdgpu_connector->ddc_bus->aux);
> > > + }
> > > +
> > > + return r;
> > > +}
> > > +
> > > static const struct drm_connector_helper_funcs
> amdgpu_connector_dp_helper_funcs = {
> > > .get_modes = amdgpu_connector_dp_get_modes,
> > > .mode_valid = amdgpu_connector_dp_mode_valid, @@ -1475,6
> > > +1489,7 @@ static const struct drm_connector_funcs
> amdgpu_connector_dp_funcs = {
> > > .early_unregister = amdgpu_connector_unregister,
> > > .destroy = amdgpu_connector_destroy,
> > > .force = amdgpu_connector_dvi_force,
> > > + .late_register = amdgpu_connector_late_register,
> > > };
> > >
> > > static const struct drm_connector_funcs amdgpu_connector_edp_funcs
> > > = { @@ -1485,6 +1500,7 @@ static const struct drm_connector_funcs
> amdgpu_connector_edp_funcs = {
> > > .early_unregister = amdgpu_connector_unregister,
> > > .destroy = amdgpu_connector_destroy,
> > > .force = amdgpu_connector_dvi_force,
> > > + .late_register = amdgpu_connector_late_register,
> > > };
> > >
> > > void
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
> > > b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
> > > index ea702a64f807..9b74cfdba7b8 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
> > > @@ -186,16 +186,10 @@ amdgpu_atombios_dp_aux_transfer(struct
> > > drm_dp_aux *aux, struct drm_dp_aux_msg *m
> > >
> > > void amdgpu_atombios_dp_aux_init(struct amdgpu_connector
> > > *amdgpu_connector) {
> > > - int ret;
> > > -
> > > amdgpu_connector->ddc_bus->rec.hpd = amdgpu_connector-
> >hpd.hpd;
> > > - amdgpu_connector->ddc_bus->aux.dev = amdgpu_connector-
> >base.kdev;
> > > amdgpu_connector->ddc_bus->aux.transfer =
> amdgpu_atombios_dp_aux_transfer;
> > > - ret = drm_dp_aux_register(&amdgpu_connector->ddc_bus->aux);
> > > - if (!ret)
> > > - amdgpu_connector->ddc_bus->has_aux = true;
> > > -
> > > - WARN(ret, "drm_dp_aux_register_i2c_bus() failed with error %d\n",
> ret);
> > > + drm_dp_aux_init(&amdgpu_connector->ddc_bus->aux);
> > > + amdgpu_connector->ddc_bus->has_aux = true;
> > > }
> > >
> > > /***** general DP utility functions *****/ diff --git
> > > a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > > index 3959c942c88b..d5b9e72f2649 100644
> > > ---
> a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > > +++
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > > @@ -155,6 +155,11 @@
> amdgpu_dm_mst_connector_late_register(struct drm_connector
> *connector)
> > > struct amdgpu_dm_connector *amdgpu_dm_connector =
> > > to_amdgpu_dm_connector(connector);
> > > struct drm_dp_mst_port *port = amdgpu_dm_connector->port;
> > > + int r;
> > > +
> > > + r = drm_dp_aux_register(&amdgpu_dm_connector->dm_dp_aux.aux);
> >
> > This calls drm_dp_aux_register_devnode which is also called later in
> > drm_dp_mst_connector_late_register. Wonder if that's a problem.
>
> Does this patch help? I'm not too familiar with the MST code and I don't
> have an MST monitor.
I have an MST monitor and I can give it a spin. I'll get back to you later.
Zhan
>
> Alex
>
>
> >
> > Harry
> >
> > > + if (r)
> > > + return r;
> > >
> > > #if defined(CONFIG_DEBUG_FS)
> > > connector_debugfs_init(amdgpu_dm_connector);
> > > @@ -484,7 +489,7 @@ void amdgpu_dm_initialize_dp_connector(struct
> amdgpu_display_manager *dm,
> > > aconnector->dm_dp_aux.aux.transfer = dm_dp_aux_transfer;
> > > aconnector->dm_dp_aux.ddc_service = aconnector->dc_link->ddc;
> > >
> > > - drm_dp_aux_register(&aconnector->dm_dp_aux.aux);
> > > + drm_dp_aux_init(&aconnector->dm_dp_aux.aux);
> > > drm_dp_cec_register_connector(&aconnector->dm_dp_aux.aux,
> > > &aconnector->base);
> > >
> > >
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