On Tue, Feb 27, 2018 at 01:23:59PM -0800, José Roberto de Souza wrote: > When PSR/PSR2/GTC is enabled hardware can do AUX transactions by it > self, so lets use the mutex register that is available in gen9+ to > avoid concurrent access by hardware and driver. > Older gen handling will be done separated. > > Reference: > https://01.org/sites/default/files/documentation/intel-gfx-prm-osrc-skl-vol12-display.pdf > Page 198 - AUX programming sequence > > Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandi...@intel.com> > Reviewed-by: Rodrigo Vivi <rodrigo.v...@intel.com> > Cc: Jani Nikula <jani.nik...@linux.intel.com> > Cc: Ville Syrjälä <ville.syrj...@linux.intel.com> > Signed-off-by: José Roberto de Souza <jose.so...@intel.com> > --- > > Changelog: > v2 > - removed the PSR dependency, now getting lock all the times when available > - renamed functions to avoid nested calls > - moved register bits right after the DP_AUX_CH_MUTEX() > - removed 'drm/i915: keep AUX powered while PSR is enabled' Dhinakaran > Pandiyan will sent a better and final version > v3 > - rebased on top of Ville's AUX series > - moved port registers to above DP_AUX_CH_MUTEX() > - using intel_wait_for_register() instead of the internal version > v4 > - removed virtual function to get mutex register address > - enabling the mutex back only on aux channel init > - added the aux channel name to the timeout debug message > v5 > - renamed DP_AUX_CH_MUTEX() parameter to aux_ch > - renamed goto label when intel_dp_aux_ch_trylock() fails > > drivers/gpu/drm/i915/i915_reg.h | 9 ++++++++ > drivers/gpu/drm/i915/intel_dp.c | 47 > +++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 56 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h > index eea5b2c537d4..bce2e6dad4c4 100644 > --- a/drivers/gpu/drm/i915/i915_reg.h > +++ b/drivers/gpu/drm/i915/i915_reg.h > @@ -5385,6 +5385,15 @@ enum { > #define DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(c) (((c) - 1) << 5) > #define DP_AUX_CH_CTL_SYNC_PULSE_SKL(c) ((c) - 1) > > +#define _DPA_AUX_CH_MUTEX (dev_priv->info.display_mmio_offset + 0x6402C) > +#define _DPB_AUX_CH_MUTEX (dev_priv->info.display_mmio_offset + 0x6412C) > +#define _DPC_AUX_CH_MUTEX (dev_priv->info.display_mmio_offset + 0x6422C) > +#define _DPD_AUX_CH_MUTEX (dev_priv->info.display_mmio_offset + 0x6432C) > +#define _DPF_AUX_CH_MUTEX (dev_priv->info.display_mmio_offset + 0x6452C) > +#define DP_AUX_CH_MUTEX(aux_ch) _MMIO_PORT(aux_ch, _DPA_AUX_CH_MUTEX, > _DPB_AUX_CH_MUTEX) > +#define DP_AUX_CH_MUTEX_ENABLE (1 << 31) > +#define DP_AUX_CH_MUTEX_STATUS (1 << 30) > + > /* > * Computing GMCH M and N values for the Display Port link > * > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c > index 2a3b3ae4e3da..7f4bf77227cd 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -1081,6 +1081,42 @@ static uint32_t intel_dp_get_aux_send_ctl(struct > intel_dp *intel_dp, > aux_clock_divider); > } > > +static bool intel_dp_aux_ch_trylock(struct intel_dp *intel_dp) > +{ > + struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp); > + struct drm_i915_private *dev_priv = > + to_i915(intel_dig_port->base.base.dev); > + > + if (INTEL_GEN(dev_priv) < 9) > + return true; > + > + /* Spec says that mutex is acquired when status bit is read as unset, > + * here waiting for 2msec(+-4 aux transactions) before give up. > + */ > + if (intel_wait_for_register(dev_priv, DP_AUX_CH_MUTEX(intel_dp->aux_ch), > + DP_AUX_CH_MUTEX_STATUS, 0, 2)) { > + DRM_DEBUG_KMS("aux channel %c locked for 2msec, timing out\n", > + aux_ch_name(intel_dp->aux_ch)); > + return false; > + } > + > + return true; > +} > + > +static void intel_dp_aux_ch_unlock(struct intel_dp *intel_dp) > +{ > + struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp); > + struct drm_i915_private *dev_priv = > + to_i915(intel_dig_port->base.base.dev); > + > + if (INTEL_GEN(dev_priv) < 9) > + return; > + > + /* set the status bit releases the mutex + keeping mutex enabled */ > + I915_WRITE(DP_AUX_CH_MUTEX(intel_dp->aux_ch), > + DP_AUX_CH_MUTEX_ENABLE | DP_AUX_CH_MUTEX_STATUS); > +} > + > static int > intel_dp_aux_ch(struct intel_dp *intel_dp, > const uint8_t *send, int send_bytes, > @@ -1119,6 +1155,11 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, > > intel_dp_check_edp(intel_dp); > > + if (!intel_dp_aux_ch_trylock(intel_dp)) { > + ret = -EBUSY; > + goto out_aux_ch_unlocked; > + } > + > /* Try to wait for any previous AUX channel activity */ > for (try = 0; try < 3; try++) { > status = I915_READ_NOTRACE(ch_ctl); > @@ -1240,6 +1281,8 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, > > ret = recv_bytes; > out: > + intel_dp_aux_ch_unlock(intel_dp); > +out_aux_ch_unlocked: > pm_qos_update_request(&dev_priv->pm_qos, PM_QOS_DEFAULT_VALUE); > > if (vdd) > @@ -1536,6 +1579,10 @@ intel_dp_aux_init(struct intel_dp *intel_dp) > else > intel_dp->get_aux_send_ctl = g4x_get_aux_send_ctl; > > + if (INTEL_GEN(dev_priv) >= 9) > + I915_WRITE(DP_AUX_CH_MUTEX(intel_dp->aux_ch), > + DP_AUX_CH_MUTEX_ENABLE);
And who enables it after system/runtime PM etc.? Not sure how much sense there is to finesse this anyway. One extra mmio write every time we try to acquire the mutex shouldn't kill anyone. > + > drm_dp_aux_init(&intel_dp->aux); > > /* Failure to allocate our preferred name is not critical */ > -- > 2.16.2 -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
