Re: [PATCH 1/2 v2 addendum v2] drm/i915: Allow parsing of variable size child device entries from VBT

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 13 Aug 2015, David Weinehall <david.weinehall@linux.intel.com> wrote:
> On Wed, Aug 12, 2015 at 05:19:35PM +0300, Jani Nikula wrote:
>> On Wed, 12 Aug 2015, David Weinehall <david.weinehall@linux.intel.com> wrote:
>> > Some more fixup is needed; the bits from Antti's patch
>> > that actually expanded the struct to fully fit the newer
>> > versions of the child_device_config was part of the second
>> > patch; since that patch hasn't been merged yet we need this bit:
>> >
>> > This applies on top of the patch you already merged
>> > (the Iboost patch will need corresponding adjustment to
>> >  remove the changes I split out):
>> >
>> > Expand common_child_dev_config to be able to fit all information
>> > defined by the latest VBT specification.
>> >
>> > Signed-off-by: David Weinehall <david.weinehall@linux.intel.com>
>> > CC: Antti Koskipaa <antti.koskipaa@linux.intel.com>
>> > ---
>> >  intel_bios.c |    7 ++++++-
>> >  intel_bios.h |    4 ++++
>> >  2 files changed, 10 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
>> > index 990acc20771a..40e2cc4e7419 100644
>> > --- a/drivers/gpu/drm/i915/intel_bios.c
>> > +++ b/drivers/gpu/drm/i915/intel_bios.c
>> > @@ -1038,6 +1038,10 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
>> >  		DRM_DEBUG_KMS("No general definition block is found, no devices defined.\n");
>> >  		return;
>> >  	}
>> > +	/* Remember to keep this in sync with child_device_config;
>> > +	 * whenever a new feature is added to BDB that causes that
>> > +	 * struct to grow this needs to be updated too
>> > +	 */
>> >  	if (bdb->version < 195) {
>> >  		expected_size = 33;
>> >  	} else if (bdb->version == 195) {
>> > @@ -1051,7 +1055,8 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
>> >  	}
>> >  
>> >  	if (expected_size > sizeof(*p_child)) {
>> > -		DRM_ERROR("child_device_config cannot fit in p_child\n");
>> > +		DRM_ERROR("child_device_config (size %u) cannot fit in p_child (size %u); bdb->version: %u\n",
>> > +			  expected_size, sizeof(*p_child), bdb->version);
>> 
>> drivers/gpu/drm/i915/intel_bios.c: In function ‘parse_device_mapping’:
>> drivers/gpu/drm/i915/intel_bios.c:1058:3: warning: format ‘%u’ expects argument of type ‘unsigned int’, but argument 3 has type ‘long unsigned int’ [-Wformat=]
>>    DRM_ERROR("child_device_config (size %u) cannot fit in p_child (size %u); bdb->version: %u\n",
>>    ^
>>   CC [M]  drivers/gpu/drm/i915/intel_fifo_underrun.o
>
> Well spotted.  Or rather, stupid of me to forget that sizeof yields
> size_t as type, thus necessitating %zu as conversion specifier.
>
> Fixed version:
>
> Expand common_child_dev_config to be able to fit all information
> defined by the latest VBT specification.
>
> v2: Use proper conversion specifier for size_t (%zu)
>
> Signed-off-by: David Weinehall <david.weinehall@linux.intel.com>
> CC: Antti Koskipaa <antti.koskipaa@linux.intel.com>
>
>  intel_bios.c |    7 ++++++-
>  intel_bios.h |    4 ++++
>  2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index 990acc20771a..5673ed53797b 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -1038,6 +1038,10 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
>  		DRM_DEBUG_KMS("No general definition block is found, no devices defined.\n");
>  		return;
>  	}
> +	/* Remember to keep this in sync with child_device_config;
> +	 * whenever a new feature is added to BDB that causes that
> +	 * struct to grow this needs to be updated too
> +	 */
>  	if (bdb->version < 195) {
>  		expected_size = 33;
>  	} else if (bdb->version == 195) {
> @@ -1051,7 +1055,8 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
>  	}
>  
>  	if (expected_size > sizeof(*p_child)) {
> -		DRM_ERROR("child_device_config cannot fit in p_child\n");
> +		DRM_ERROR("child_device_config (size %u) cannot fit in p_child (size %zu); bdb->version: %u\n",
> +			  expected_size, sizeof(*p_child), bdb->version);
>  		return;
>  	}
>  
> diff --git a/drivers/gpu/drm/i915/intel_bios.h b/drivers/gpu/drm/i915/intel_bios.h
> index f7ad6a585129..71cb96f77870 100644
> --- a/drivers/gpu/drm/i915/intel_bios.h
> +++ b/drivers/gpu/drm/i915/intel_bios.h
> @@ -239,6 +239,10 @@ struct common_child_dev_config {
>  	u8 not_common2[2];
>  	u8 ddc_pin;
>  	u16 edid_ptr;
> +	u8 obsolete;
> +	u8 flags_1;
> +	u8 not_common3[13];
> +	u8 iboost_level;

How does this impact the if (p_defs->child_dev_size != sizeof(*p_child))
check in parse_sdvo_device_mapping()?

BR,
Jani.

>  } __packed;
>  
>  /* This field changes depending on the BDB version, so the most reliable way to

-- 
Jani Nikula, Intel Open Source Technology Center
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