On Mon, 2018-02-26 at 14:41 -0800, Rodrigo Vivi wrote:
> On Mon, Feb 26, 2018 at 01:48:37PM -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
> >
> > Cc: Rodrigo Vivi <[email protected]>
> > Cc: Jani Nikula <[email protected]>
> > Cc: Dhinakaran Pandiyan <[email protected]>
> > Cc: Ville Syrjälä <[email protected]>
> > Signed-off-by: José Roberto de Souza <[email protected]>
> > ---
> > 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..f36e839b4b4f 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(port) _MMIO_PORT(port, _DPA_AUX_CH_MUTEX,
> > _DPB_AUX_CH_MUTEX)
>
> s/port/aux_ch
>
> > +#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 2c3eb90b9499..7004239e4c9e 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;
> > + }
> > +
With nits that Rodrigo pointed out addressed, feel free to use
Reviewed-by: Dhinakaran Pandiyan <[email protected]>
Btw for future reference, including change log in the commit message is
a good idea in the absence of a cover letter.
> > + 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_locked;
>
> out_"locked" confused me here...
>
> not sure about a better name...
>
> maybe out_aux_unlocked ?! :/
>
> > + }
> > +
> > /* Try to wait for any previous AUX channel activity */
> > for (try = 0; try < 3; try++) {
> > status = I915_READ_NOTRACE(ch_ctl);
> > @@ -1248,6 +1289,8 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
> >
> > ret = recv_bytes;
> > out:
> > + intel_dp_aux_ch_unlock(intel_dp);
> > +out_locked:
> > pm_qos_update_request(&dev_priv->pm_qos, PM_QOS_DEFAULT_VALUE);
> >
> > if (vdd)
> > @@ -1544,6 +1587,10 @@ 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);
> > +
>
> Cool! I believe we are in a good shape now...
>
> with s/port/aux_ch corrected and preferably with a better goto out name:
>
> Reviewed-by: Rodrigo Vivi <[email protected]>
>
> > drm_dp_aux_init(&intel_dp->aux);
> >
> > /* Failure to allocate our preferred name is not critical */
> > --
> > 2.16.2
> >
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