On Mon, Sep 30, 2019 at 05:55:36PM -0700, José Roberto de Souza wrote:
> This is required for legacy/static TC ports as IOM is not aware of
> the connection and will not trigger the TC cold exit.
>
> BSpec: 21750
> BSpsc: 49294
> Cc: Imre Deak <imre.deak@xxxxxxxxx>
> Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
> Signed-off-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_tc.c | 34 ++++++++++++++++++++-----
> drivers/gpu/drm/i915/i915_reg.h | 1 +
> 2 files changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_tc.c b/drivers/gpu/drm/i915/display/intel_tc.c
> index 7773169b7331..09b78027bdd5 100644
> --- a/drivers/gpu/drm/i915/display/intel_tc.c
> +++ b/drivers/gpu/drm/i915/display/intel_tc.c
> @@ -7,6 +7,7 @@
> #include "intel_display.h"
> #include "intel_display_types.h"
> #include "intel_dp_mst.h"
> +#include "intel_sideband.h"
> #include "intel_tc.h"
>
> static const char *tc_port_mode_name(enum tc_port_mode mode)
> @@ -169,6 +170,22 @@ static void tc_port_fixup_legacy_flag(struct intel_digital_port *dig_port,
> dig_port->tc_legacy_port = !dig_port->tc_legacy_port;
> }
>
> +static int tc_cold_exit_request(struct drm_i915_private *dev_priv)
> +{
> + int ret;
> +
> + do {
> + ret = sandybridge_pcode_write_timeout(dev_priv,
> + ICL_PCODE_EXIT_TCCOLD, 0,
> + 250, 1);
> +
> + } while (ret == -EAGAIN);
> +
> + DRM_DEBUG_KMS("tccold exit %s\n", ret == 0 ? "succeeded" : "failed");
> +
> + return ret;
> +}
> +
> static u32 tc_port_live_status_mask(struct intel_digital_port *dig_port)
> {
> struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
> @@ -177,13 +194,21 @@ static u32 tc_port_live_status_mask(struct intel_digital_port *dig_port)
> u32 mask = 0;
> u32 val;
>
> + if (intel_uncore_read(uncore, SDEISR) & SDE_TC_HOTPLUG_ICP(tc_port))
> + mask |= BIT(TC_PORT_LEGACY);
> +
> val = intel_uncore_read(uncore,
> PORT_TX_DFLEXDPSP(dig_port->tc_phy_fia));
>
> if (val == 0xffffffff) {
> - DRM_DEBUG_KMS("Port %s: PHY in TCCOLD, nothing connected\n",
> - dig_port->tc_port_name);
> - return mask;
> + if (mask)
> + tc_cold_exit_request(i915);
The semantic of the mbox command this needs is inherently racy on
systems with preemption, the instruction to use it is:
"""
Issue GT Driver mailbox command to exit TCCOLD, then complete steps b-d
within 500 milliseconds to prevent re-entry.
"""
We'd have to reach the point where we enable the AUX power in 500ms,
which can't be guaranteed. Moreover TCCOLD could be entered just after
reading PORT_TX_DFLEXDPSP, so we may not detect it.
What we can do - after discussing with HW folks - is to first request
AUX power and then issue the mbox command, which prevents TCCOLD
re-entry until releasing the AUX power request. This also needs ignoring
the timeout of the AUX power enabling ACK, since it will only be ACKed
after exiting TCCOLD.
So I think we should block TCCOLD this way in __intel_tc_port_lock():
if tc_link_refcount==0:
intel_display_power_get(POWER_DOMAIN_AUX_<port>)
tc_cold_exit_request()
if intel_tc_port_needs_reset():
intel_tc_port_reset_mode()
if tc_mode != LEGACY:
intel_display_power_put(POWER_DOMAIN_AUX_<port>)
then unblock TCCOLD in intel_tc_port_unlock():
if tc_link_refcount==0 and tc_mode == LEGACY:
intel_display_power_put(POWER_DOMAIN_AUX_<port>)
> +
> + if (val == 0xffffffff) {
> + DRM_DEBUG_KMS("Port %s: PHY in TCCOLD, nothing connected\n",
> + dig_port->tc_port_name);
> + return mask;
> + }
> }
>
> if (val & TC_LIVE_STATE_TBT(dig_port->tc_phy_fia_idx))
> @@ -191,9 +216,6 @@ static u32 tc_port_live_status_mask(struct intel_digital_port *dig_port)
> if (val & TC_LIVE_STATE_TC(dig_port->tc_phy_fia_idx))
> mask |= BIT(TC_PORT_DP_ALT);
>
> - if (intel_uncore_read(uncore, SDEISR) & SDE_TC_HOTPLUG_ICP(tc_port))
> - mask |= BIT(TC_PORT_LEGACY);
> -
> /* The sink can be connected only in a single mode. */
> if (!WARN_ON(hweight32(mask) > 1))
> tc_port_fixup_legacy_flag(dig_port, mask);
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 058aa5ca8b73..35c3724b7fef 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -8860,6 +8860,7 @@ enum {
> #define ICL_PCODE_MEM_SS_READ_QGV_POINT_INFO(point) (((point) << 16) | (0x1 << 8))
> #define GEN6_PCODE_READ_D_COMP 0x10
> #define GEN6_PCODE_WRITE_D_COMP 0x11
> +#define ICL_PCODE_EXIT_TCCOLD 0x12
> #define HSW_PCODE_DE_WRITE_FREQ_REQ 0x17
> #define DISPLAY_IPS_CONTROL 0x19
> /* See also IPS_CTL */
> --
> 2.23.0
>
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