[PATCH] drm/i915: Mark fastboot as unsafe

[PATCH] drm/i915: Mark fastboot as unsafe

[Daniel Vetter]

Fastboot in its current incarnation assumes that the pfit isn't
relevatn for the state and that it can be disabled without restarting
the crtc. Unfortunately that's not the case on gen2/3 - it upsets the
hw and results in a black screen.

Worse, the way the current fastboot hack is structure we can't detect
and work around this in the code, since the fastboot smashes the
adjusted mode into crtc->mode. Which means the higher levels can't
correctly figure out that this is a lie and act accordingly.

Since fastboot is just a tech demo let's mark the module option as
experimental and close the coresponding reports as wontfix.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84682
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
 drivers/gpu/drm/i915/i915_params.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index c91cb2033cc5..93d792349668 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -138,7 +138,7 @@ MODULE_PARM_DESC(disable_power_well,
 module_param_named(enable_ips, i915.enable_ips, int, 0600);
 MODULE_PARM_DESC(enable_ips, "Enable IPS (default: true)");
 
-module_param_named(fastboot, i915.fastboot, bool, 0600);
+module_param_named_unsafe(fastboot, i915.fastboot, bool, 0600);
 MODULE_PARM_DESC(fastboot,
 	"Try to skip unnecessary mode sets at boot time (default: false)");
 
-- 
2.1.1

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx

Re: [PATCH] drm/i915: Mark fastboot as unsafe

[Paul Menzel]

[-- Attachment #1.1: Type: text/plain, Size: 1844 bytes --]

Dear Daniel,


thank you for the support in #intel-gfx@irc.freenode.net and the patch.
As already commented in the bug report #84682, there are some typos.

Am Dienstag, den 04.11.2014, 15:29 +0100 schrieb Daniel Vetter:
> Fastboot in its current incarnation assumes that the pfit isn't
> relevatn for the state and that it can be disabled without restarting

releva*nt*

> the crtc. Unfortunately that's not the case on gen2/3 - it upsets the
> hw and results in a black screen.
> 
> Worse, the way the current fastboot hack is structure we can't detect

structure*d*

> and work around this in the code, since the fastboot smashes the
> adjusted mode into crtc->mode. Which means the higher levels can't
> correctly figure out that this is a lie and act accordingly.
> 
> Since fastboot is just a tech demo let's mark the module option as
> experimental and close the coresponding reports as wontfix.

cor*r*esponding

> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84682
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_params.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index c91cb2033cc5..93d792349668 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -138,7 +138,7 @@ MODULE_PARM_DESC(disable_power_well,
>  module_param_named(enable_ips, i915.enable_ips, int, 0600);
>  MODULE_PARM_DESC(enable_ips, "Enable IPS (default: true)");
>  
> -module_param_named(fastboot, i915.fastboot, bool, 0600);
> +module_param_named_unsafe(fastboot, i915.fastboot, bool, 0600);
>  MODULE_PARM_DESC(fastboot,
>  	"Try to skip unnecessary mode sets at boot time (default: false)");


Thanks,

Paul

[-- Attachment #1.2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx

Re: [PATCH] drm/i915: Mark fastboot as unsafe

[Daniel Vetter]

On Tue, Nov 04, 2014 at 03:29:57PM +0100, Daniel Vetter wrote:
> Fastboot in its current incarnation assumes that the pfit isn't
> relevatn for the state and that it can be disabled without restarting
> the crtc. Unfortunately that's not the case on gen2/3 - it upsets the
> hw and results in a black screen.
> 
> Worse, the way the current fastboot hack is structure we can't detect
> and work around this in the code, since the fastboot smashes the
> adjusted mode into crtc->mode. Which means the higher levels can't
> correctly figure out that this is a lie and act accordingly.
> 
> Since fastboot is just a tech demo let's mark the module option as
> experimental and close the coresponding reports as wontfix.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84682
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

Jesse expressed concerns in private about this patch, so I've dropped it
and the other fastboot patch.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx

Re: [PATCH] drm/i915: Mark fastboot as unsafe

[Jesse Barnes]

On Fri, 7 Nov 2014 18:41:16 +0100
Daniel Vetter <daniel@ffwll.ch> wrote:

> On Tue, Nov 04, 2014 at 03:29:57PM +0100, Daniel Vetter wrote:
> > Fastboot in its current incarnation assumes that the pfit isn't
> > relevatn for the state and that it can be disabled without
> > restarting the crtc. Unfortunately that's not the case on gen2/3 -
> > it upsets the hw and results in a black screen.
> > 
> > Worse, the way the current fastboot hack is structure we can't
> > detect and work around this in the code, since the fastboot smashes
> > the adjusted mode into crtc->mode. Which means the higher levels
> > can't correctly figure out that this is a lie and act accordingly.
> > 
> > Since fastboot is just a tech demo let's mark the module option as
> > experimental and close the coresponding reports as wontfix.
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84682
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> 
> Jesse expressed concerns in private about this patch, so I've dropped
> it and the other fastboot patch.

I don't think this patch addresses the referenced bug, and it also
implies that we don't care about ever making fastboot the default, so
can ignore any related buts.  The latter surely isn't true in my mind
at least, which is why I've been pushing additional fixes, as recently
as the same day as this patch, so I'm a bit confused about the summary.

As for pfit handling issues, can you be more specific about the case
you want to support that we don't today?  The recent patch for checking
whether pfit requires a full mode set should address your first point,
but I don't know what exactly you mean in your second paragraph...

Thanks,
Jesse
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx