On Thu, Dec 10, 2015 at 08:28:23AM -0800, Rodrigo Vivi wrote:
> Link standby support has been deprecated with 'commit 89251b177
> ("drm/i915: PSR: deprecate link_standby support for core platforms.")'
>
> The reason for that is that main link in full off offers more power
> savings and some platforms implementations on source side had known
> bugs with link standby.
>
> However we don't know all panels out there and we don't fully rely
> on the VBT information after the case found with the commit that
> made us to deprecate link standby.
>
> So, before enable PSR by default let's instrument the PSR parameter
> in a way that we can identify different panels out there that might
> require or work better with link standby mode.
>
> It is also useful to say that for backward compatibility I'm not
> changing the meaning of this flag. So "0" still means disabled
> and "1" means enabled with full support and maximum power savings.
>
> Negative values are being used for debug purposes since I'd like
> to save positive number for future use like PSR2 for instance.
>
> Cc: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 5 +++++
> drivers/gpu/drm/i915/i915_drv.h | 1 +
> drivers/gpu/drm/i915/i915_params.c | 7 ++++++-
> drivers/gpu/drm/i915/intel_psr.c | 13 ++++++++++++-
> 4 files changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 24318b7..efe973b 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -2567,6 +2567,10 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
> enabled = true;
> }
> }
> +
> + seq_printf(m, "Forcing main link standby: %s\n",
> + yesno(dev_priv->psr.link_standby));
> +
> seq_printf(m, "HW Enabled & Active bit: %s", yesno(enabled));
>
> if (!HAS_DDI(dev))
> @@ -2587,6 +2591,7 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
>
> seq_printf(m, "Performance_Counter: %u\n", psrperf);
> }
> +
> mutex_unlock(&dev_priv->psr.lock);
>
> intel_runtime_pm_put(dev_priv);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 5edd393..de086f0 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -969,6 +969,7 @@ struct i915_psr {
> unsigned busy_frontbuffer_bits;
> bool psr2_support;
> bool aux_frame_sync;
> + bool link_standby;
> };
>
> enum intel_pch {
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index 835d609..def8802 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -126,7 +126,12 @@ MODULE_PARM_DESC(enable_execlists,
> "(-1=auto [default], 0=disabled, 1=enabled)");
>
> module_param_named_unsafe(enable_psr, i915.enable_psr, int, 0600);
> -MODULE_PARM_DESC(enable_psr, "Enable PSR (default: false)");
> +MODULE_PARM_DESC(enable_psr, "Enable PSR "
> + "(-1=force link standby for debug, 0=disabled [default], 1=enabled)"
-1 usually means debug, and values >= 1 are for different enabling modes.
Otherwise makes sense I'd say.
-Daniel
> + "In case you needed to force debug mode, please "
> + "report PCI device ID, subsystem vendor and subsystem device ID "
> + "to intel-gfx@xxxxxxxxxxxxxxxxxxxxx, if your machine needs it. "
> + "It will then be included in an upcoming module version.");
>
> module_param_named_unsafe(preliminary_hw_support, i915.preliminary_hw_support, int, 0600);
> MODULE_PARM_DESC(preliminary_hw_support,
> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
> index 9ccff30..7529f93 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -225,7 +225,12 @@ static void hsw_psr_enable_sink(struct intel_dp *intel_dp)
> (aux_clock_divider << DP_AUX_CH_CTL_BIT_CLOCK_2X_SHIFT));
> }
>
> - drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, DP_PSR_ENABLE);
> + if (dev_priv->psr.link_standby)
> + drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG,
> + DP_PSR_ENABLE | DP_PSR_MAIN_LINK_ACTIVE);
> + else
> + drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG,
> + DP_PSR_ENABLE);
> }
>
> static void vlv_psr_enable_source(struct intel_dp *intel_dp)
> @@ -280,6 +285,9 @@ static void hsw_psr_enable_source(struct intel_dp *intel_dp)
> if (IS_HASWELL(dev))
> val |= EDP_PSR_MIN_LINK_ENTRY_TIME_8_LINES;
>
> + if (dev_priv->psr.link_standby)
> + val |= EDP_PSR_LINK_STANDBY;
> +
> I915_WRITE(EDP_PSR_CTL, val |
> max_sleep_time << EDP_PSR_MAX_SLEEP_TIME_SHIFT |
> idle_frames << EDP_PSR_IDLE_FRAME_SHIFT |
> @@ -763,6 +771,9 @@ void intel_psr_init(struct drm_device *dev)
> dev_priv->psr_mmio_base = IS_HASWELL(dev_priv) ?
> HSW_EDP_PSR_BASE : BDW_EDP_PSR_BASE;
>
> + if (i915.enable_psr == -1)
> + dev_priv->psr.link_standby = true;
> +
> INIT_DELAYED_WORK(&dev_priv->psr.work, intel_psr_work);
> mutex_init(&dev_priv->psr.lock);
> }
> --
> 2.4.3
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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