Re: [PATCH] drm/i915: Enable fastboot by default on Skylake and newer

[Hans de Goede <hdegoede@xxxxxxxxxx>]

Hi Rodrigo and Maarten,

On 24-01-19 23:20, Rodrigo Vivi wrote:
> On Thu, Jan 24, 2019 at 02:01:14PM +0100, Maarten Lankhorst wrote:
> > From: Hans de Goede <hdegoede@xxxxxxxxxx>
> >
> > We really want to have fastboot enabled by default to avoid an ugly
> > modeset during boot.
> >
> > Rather then enabling it everywhere, lets start with enabling it on
> > Skylake and newer.
> >
> > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
>
>
> I believe at this point you both addressed all of my concerns.
> And CI is happy. Let's give a try ;)

Great, thank you.

On IRC Maarten asked me about if we should also enable this for
VLV/CHV. As you may know, as a spare time/weekend project, I've been
working on making Linux support Bay and Cherry Trail based hardware,
better. As such I've about 40 different devices with these SoCs and
I've tested fastboot=1 on all of them. fastboot=1 not only works on
all of them, on 2 devices the display goes black when we have
fastboot=0 for some reason which I've been unable to figure out.
These 2 devices do survive a full-modeset just fine after the initial
one ?

So my response to Maarten was, yes we should enable fastboot=1 by
default on VLV/CHV too and I plan to submit a follow-up patch for
that once we have agreement on this patch.

Maarten suggested to just go for enabling it on gen7+ instead of
the current gen9+.

I personally tend towards merging this patch with your
Reviewed-by + doing a follow-up patch for just VLV/CHV, but
Maarten prefers doing the gen7+ solution, what is your take on this?

Regards,

Hans





> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>
>
>
> > ---
> >   drivers/gpu/drm/i915/i915_params.c   |  6 ++++--
> >   drivers/gpu/drm/i915/i915_params.h   |  2 +-
> >   drivers/gpu/drm/i915/intel_display.c | 11 ++++++++++-
> >   3 files changed, 15 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> > index 9f0539bdaa39..b5be0abbba35 100644
> > --- a/drivers/gpu/drm/i915/i915_params.c
> > +++ b/drivers/gpu/drm/i915/i915_params.c
> > @@ -97,8 +97,10 @@ i915_param_named_unsafe(disable_power_well, int, 0400,
> >
> >   i915_param_named_unsafe(enable_ips, int, 0600, "Enable IPS (default: true)");
> >
> > -i915_param_named(fastboot, bool, 0600,
> > -	"Try to skip unnecessary mode sets at boot time (default: false)");
> > +i915_param_named(fastboot, int, 0600,
> > +	"Try to skip unnecessary mode sets at boot time "
> > +	"(0=disabled, 1=enabled) "
> > +	"Default: -1 (use per-chip default)");
> >
> >   i915_param_named_unsafe(prefault_disable, bool, 0600,
> >   	"Disable page prefaulting for pread/pwrite/reloc (default:false). "
> > diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
> > index 6efcf330bdab..3f14e9881a0d 100644
> > --- a/drivers/gpu/drm/i915/i915_params.h
> > +++ b/drivers/gpu/drm/i915/i915_params.h
> > @@ -63,10 +63,10 @@ struct drm_printer;
> >   	param(int, edp_vswing, 0) \
> >   	param(int, reset, 2) \
> >   	param(unsigned int, inject_load_failure, 0) \
> > +	param(int, fastboot, -1) \
> >   	/* leave bools at the end to not create holes */ \
> >   	param(bool, alpha_support, IS_ENABLED(CONFIG_DRM_I915_ALPHA_SUPPORT)) \
> >   	param(bool, enable_hangcheck, true) \
> > -	param(bool, fastboot, false) \
> >   	param(bool, prefault_disable, false) \
> >   	param(bool, load_detect_test, false) \
> >   	param(bool, force_reset_modeset_test, false) \
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 36c1126cbc85..097e46819d3a 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -11690,6 +11690,15 @@ pipe_config_err(bool adjust, const char *name, const char *format, ...)
> >   	va_end(args);
> >   }
> >
> > +static bool fastboot_enabled(struct drm_i915_private *dev_priv)
> > +{
> > +	if (i915_modparams.fastboot != -1)
> > +		return i915_modparams.fastboot;
> > +
> > +	/* Enable fastboot by default on Skylake and newer */
> > +	return INTEL_GEN(dev_priv) >= 9;
> > +}
> > +
> >   static bool
> >   intel_pipe_config_compare(struct drm_i915_private *dev_priv,
> >   			  struct intel_crtc_state *current_config,
> > @@ -11701,7 +11710,7 @@ intel_pipe_config_compare(struct drm_i915_private *dev_priv,
> >   		(current_config->base.mode.private_flags & I915_MODE_FLAG_INHERITED) &&
> >   		!(pipe_config->base.mode.private_flags & I915_MODE_FLAG_INHERITED);
> >
> > -	if (fixup_inherited && !i915_modparams.fastboot) {
> > +	if (fixup_inherited && !fastboot_enabled(dev_priv)) {
> >   		DRM_DEBUG_KMS("initial modeset and fastboot not set\n");
> >   		ret = false;
> >   	}
> > --
> > 2.20.1
> >
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