On Fri, May 24, 2019 at 08:35:32PM +0300, Imre Deak wrote:
> Atm AUX-B transfers can fail with the following error if AUX-A is not
> enabled:
>
> [ 594.594108] [drm:intel_dp_aux_xfer [i915]] dp_aux_ch timeout status
> 0x7c2003ff
> [ 594.615854] [drm:intel_dp_aux_xfer [i915]] *ERROR* dp aux hw did not
> signal timeout!
> [ 594.632851] [drm:intel_dp_aux_xfer [i915]] *ERROR* dp aux hw did not
> signal timeout!
> [ 594.632915] [drm:intel_dp_aux_xfer [i915]] *ERROR* dp_aux_ch not done
> status 0xac2003ff
> [ 594.641786] ------------[ cut here ]------------
> [ 594.641790] dp_aux_ch not started status 0xac2003ff
> [ 594.641874] WARNING: CPU: 4 PID: 1366 at
> drivers/gpu/drm/i915/intel_dp.c:1268 intel_dp_aux_xfer+0x232/0x890 [i915]
>
> Ville noticed this issue already earlier and managed to work around it
> by keeping AUX-A always powered whenever AUX-B was used. He also
> reported the issue to HW folks and they have now root caused the problem
> and updated BSpec with a fix (see internal BSpec/Index/21257,
> HSD/1607152412).
>
> I noticed the same error - even with the WA being applied - while doing
> AUX transfers with Chamelium being connected with a DP cable to the
> source but letting Chamelium imitate an unplug. This is probably some
> unstandard way on Chamelium's behalf of disconnecting itself from the
> AUX pins. For instance it could still pull on the AUX pins which would
> prevent the source from detecting AUX timeouts in the proper way,
> leading to the ERRORs or WARNs seen in the logs in the Reference: bug
> below.
>
> In case I disconnect the sink properly (the cable itself, not via the
> Chamelium unplug xmlrpc command) then the AUX timeout signaling works
> properly and so there won't be any ERRORs/WARNs emitted.
>
> Reference: https://bugs.freedesktop.org/show_bug.cgi?id=110718
> Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
> Reported-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
> Signed-off-by: Imre Deak <imre.d...@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
> ---
> drivers/gpu/drm/i915/i915_reg.h | 3 +++
> drivers/gpu/drm/i915/intel_combo_phy.c | 6 ++++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 87e8780711d7..bae4a2547eb2 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1846,6 +1846,9 @@ enum i915_power_well_id {
> #define VOLTAGE_INFO_MASK (3 << 24)
> #define VOLTAGE_INFO_SHIFT 24
>
> +#define ICL_PORT_COMP_DW8(port) _MMIO(_ICL_PORT_COMP_DW(8,
> port))
> +#define IREFGEN (1 << 24)
> +
> #define CNL_PORT_COMP_DW9 _MMIO(0x162124)
> #define ICL_PORT_COMP_DW9(port) _MMIO(_ICL_PORT_COMP_DW(9,
> port))
>
> diff --git a/drivers/gpu/drm/i915/intel_combo_phy.c
> b/drivers/gpu/drm/i915/intel_combo_phy.c
> index 19a9333b727a..98213cc58736 100644
> --- a/drivers/gpu/drm/i915/intel_combo_phy.c
> +++ b/drivers/gpu/drm/i915/intel_combo_phy.c
> @@ -275,6 +275,12 @@ static void icl_combo_phys_init(struct drm_i915_private
> *dev_priv)
>
> cnl_set_procmon_ref_values(dev_priv, port);
>
> + if (port == PORT_A) {
> + val = I915_READ(ICL_PORT_COMP_DW8(port));
> + val |= IREFGEN;
> + I915_WRITE(ICL_PORT_COMP_DW8(port), val);
> + }
> +
> val = I915_READ(ICL_PORT_COMP_DW0(port));
> val |= COMP_INIT;
> I915_WRITE(ICL_PORT_COMP_DW0(port), val);
> --
> 2.17.1
--
Ville Syrjälä
Intel
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