[Intel-gfx] [PATCH] drm/i915: Enable fastboot by default on Skylake and newer

[Hans de Goede]

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 at redhat.com>
>>
>> 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 at redhat.com>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> 
> 
> 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 at intel.com>
> 
> 
> 
>> ---
>>   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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