Re: [PATCH 1/3] drm/i915/opregion: fix version check

From: Imre Deak <imre.deak@intel.com>
To: Jani Nikula <jani.nikula@intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/3] drm/i915/opregion: fix version check
Date: Fri, 8 Feb 2019 17:11:41 +0200	[thread overview]
Message-ID: <20190208151141.GG31034@ideak-desk.fi.intel.com> (raw)
In-Reply-To: <87sgwy5nb4.fsf@intel.com>

On Fri, Feb 08, 2019 at 05:09:51PM +0200, Jani Nikula wrote:
> On Fri, 08 Feb 2019, Jani Nikula <jani.nikula@intel.com> wrote:
> > The u32 version field encodes major version in the high word. We've been
> > checking for version >= 0.2.
> >
> > Add opregion version logging while at it.
> >
> > Fixes: 04ebaadb9f2d ("drm/i915/opregion: handle VBT sizes bigger than 6 KB")
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: Imre Deak <imre.deak@intel.com>
> > Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_opregion.c | 11 +++++++++--
> >  1 file changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
> > index 30ae96c5c97c..7e4152d97c45 100644
> > --- a/drivers/gpu/drm/i915/intel_opregion.c
> > +++ b/drivers/gpu/drm/i915/intel_opregion.c
> > @@ -46,6 +46,9 @@
> >  #define OPREGION_ASLE_EXT_OFFSET	0x1C00
> >  
> >  #define OPREGION_SIGNATURE "IntelGraphicsMem"
> > +
> > +#define OPREGION_VERSION(major, minor) (((major) << 16) | (minor))
> > +
> >  #define MBOX_ACPI      (1<<0)
> >  #define MBOX_SWSCI     (1<<1)
> >  #define MBOX_ASLE      (1<<2)
> > @@ -924,6 +927,10 @@ int intel_opregion_setup(struct drm_i915_private *dev_priv)
> >  	opregion->header = base;
> >  	opregion->lid_state = base + ACPI_CLID;
> >  
> > +	DRM_DEBUG_DRIVER("ACPI OpRegion version %u.%u\n",
> > +			 opregion->header->opregion_ver >> 16,
> > +			 opregion->header->opregion_ver & 0xffff);
> > +
> 
> This is ridiculous and maddening. On our CI APL this prints [1]:
> 
> <7>[    7.029368] [drm:intel_opregion_setup [i915]] ACPI OpRegion version 512.0
> 
> Yes, version 512.0.
> 
> Digging into it, I found one random version of the opregion spec that
> has:
> 
> 	Bits [31:16] - Major Version Number
> 	Bits [23:0] - Minor Version Number
> 
> The minor is supposed to be [15:0]. But this APL (maybe others, need to
> investigate) has the major version encoded to bits 31:24.
> 
> This obviously screws up the opregion version check in patch 2 as well,
> leading to relative RVDA being used.

Maybe you should use another version field to decode this version field.
Just kidding:)

> 
> Absolutely disgusting.
> 
> 
> BR,
> Jani.
> 
> 
> [1] https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_12175/fi-apl-guc/boot0.log
> 
> 
> >  	mboxes = opregion->header->mboxes;
> >  	if (mboxes & MBOX_ACPI) {
> >  		DRM_DEBUG_DRIVER("Public ACPI methods supported\n");
> > @@ -952,8 +959,8 @@ int intel_opregion_setup(struct drm_i915_private *dev_priv)
> >  	if (dmi_check_system(intel_no_opregion_vbt))
> >  		goto out;
> >  
> > -	if (opregion->header->opregion_ver >= 2 && opregion->asle &&
> > -	    opregion->asle->rvda && opregion->asle->rvds) {
> > +	if (opregion->header->opregion_ver >= OPREGION_VERSION(2, 0) &&
> > +	    opregion->asle && opregion->asle->rvda && opregion->asle->rvds) {
> >  		opregion->rvda = memremap(opregion->asle->rvda,
> >  					  opregion->asle->rvds,
> >  					  MEMREMAP_WB);
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center
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