Re: [PATCH] drm/i915/bxt, glk: Increase PCODE timeouts during CDCLK freq changing

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Apr 24, 2018 at 06:19:16PM +0300, Imre Deak wrote:
> commit 5e1df40f40ee45a97bb1066c3d71f0ae920a9672 upstream.
> 
> Currently we see sporadic timeouts during CDCLK changing both on BXT and
> GLK as reported by the Bugzilla: ticket. It's easy to reproduce this by
> changing the frequency in a tight loop after blanking the display. The
> upper bound for the completion time is 800us based on my tests, so
> increase it from the current 500us to 2ms; with that I couldn't trigger
> the problem either on BXT or GLK.
> 
> Note that timeouts happened during both the change notification and the
> voltage level setting PCODE request. (For the latter one BSpec doesn't
> require us to wait for completion before further HW programming.)
> 
> This issue is similar to
> commit 2c7d0602c815 ("drm/i915/gen9: Fix PCODE polling during CDCLK
> change notification")
> but there the PCODE request does complete (as shown by the mbox
> busy flag), only the reply we get from PCODE indicates a failure.
> So there we keep resending the request until a success reply, here we
> just have to increase the timeout for the one PCODE request we send.
> 
> v2:
> - s/snb_pcode_request/sandybridge_pcode_write_timeout/ (Ville)
> 
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Ville Syrj�l� <ville.syrjala@linux.intel.com>
> Cc: <stable@vger.kernel.org> # v4.9
> Acked-by: Chris Wilson <chris@chris-wilson.co.uk> (v1)
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103326
> Reviewed-by: Ville Syrj�l� <ville.syrjala@linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> Link: https://patchwork.freedesktop.org/patch/msgid/20180130142939.17983-1-imre.deak@intel.com
> (cherry picked from commit e76019a81921e87a4d9e7b3d86102bc708a6c227)
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> (Rebased for v4.9 stable tree due to upstream intel_cdclk.c, cdclk_state and pcu_lock change)
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h      | 6 +++++-
>  drivers/gpu/drm/i915/intel_display.c | 9 +++++----
>  drivers/gpu/drm/i915/intel_pm.c      | 6 +++---
>  3 files changed, 13 insertions(+), 8 deletions(-)

Now queued up, thanks.

greg k-h