[PATCH i-g-t 0/4] intel_vbt_decode: fall back to guessing PCI ID from VBT signature

[PATCH i-g-t 0/4] intel_vbt_decode: fall back to guessing PCI ID from VBT signature

[Jani Nikula]

This is inspired by Michał's patch [1], and I got kind of carried away
trying to figure out how to infer the stuff from the existing codenames
in intel_device_info.c. I didn't mean to do it, but here it is. :)

BR,
Jani.


[1] https://lore.kernel.org/r/20260608124121.3131410-6-michal.grzelak@intel.com


Jani Nikula (3):
  tools/intel_vbt_decode: store codename from VBT signature to context
  lib/intel_device_info: add a helper to guess the PCI ID for a codename
  tools/intel_vbt_decode: fall back to guessing PCI ID from VBT
    signature

Michał Grzelak (1):
  tools/vbt_decode: return 0 from get_device_id()

 lib/intel_chipset.h      |  1 +
 lib/intel_device_info.c  | 75 ++++++++++++++++++++++++++++++++++++++++
 tools/intel_vbt_decode.c | 35 +++++++++++++------
 3 files changed, 100 insertions(+), 11 deletions(-)

-- 
2.47.3

[PATCH i-g-t 1/4] tools/intel_vbt_decode: store codename from VBT signature to context

[Jani Nikula]

The VBT often contains something resembling a codename in the
signature. Currently, we only use it for printing a description of sorts
(the --describe option). Store the codename-ish to context for more use.

Cc: Michał Grzelak <michal.grzelak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 tools/intel_vbt_decode.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/tools/intel_vbt_decode.c b/tools/intel_vbt_decode.c
index cf7bcc5771a4..5b39e0c1c33e 100644
--- a/tools/intel_vbt_decode.c
+++ b/tools/intel_vbt_decode.c
@@ -74,6 +74,8 @@ struct context {
 	const struct bdb_header *bdb;
 	int size;
 
+	char codename[sizeof(((struct vbt_header *)0)->signature) + 1];
+
 	uint32_t devid;
 	int panel_type, panel_type2;
 	int sdvo_panel_type;
@@ -4023,31 +4025,38 @@ static bool dump_section(struct context *context, int section_id)
 	return true;
 }
 
-/* print a description of the VBT of the form <bdb-version>-<vbt-signature> */
-static void print_description(struct context *context)
+/* initialize something resembling a codename based on the signature */
+static void init_codename(struct context *context)
 {
 	const struct vbt_header *vbt = context->vbt;
-	const struct bdb_header *bdb = context->bdb;
-	char *desc = strndup((char *)vbt->signature, sizeof(vbt->signature));
+	char signature[sizeof(vbt->signature) + 1] = {};
 	char *p;
 
-	for (p = desc + strlen(desc) - 1; p >= desc && isspace(*p); p--)
+	memcpy(signature, vbt->signature, sizeof(vbt->signature));
+
+	for (p = signature + strlen(signature) - 1; p >= signature && isspace(*p); p--)
 		*p = '\0';
 
-	for (p = desc; *p; p++) {
+	for (p = signature; *p; p++) {
 		if (!isalnum(*p))
 			*p = '-';
 		else
 			*p = tolower(*p);
 	}
 
-	p = desc;
+	p = signature;
 	if (strncmp(p, "-vbt-", 5) == 0)
 		p += 5;
 
-	printf("%d-%s\n", bdb->version, p);
+	strncpy(context->codename, p, sizeof(context->codename));
+}
+
+/* print a description of the VBT of the form <bdb-version>-<vbt-signature> */
+static void print_description(struct context *context)
+{
+	const struct bdb_header *bdb = context->bdb;
 
-	free (desc);
+	printf("%d-%s\n", bdb->version, context->codename);
 }
 
 static void dump_headers(struct context *context)
@@ -4313,6 +4322,8 @@ int main(int argc, char **argv)
 	context.bdb = (const struct bdb_header *)(VBIOS + bdb_off);
 	context.size = size;
 
+	init_codename(&context);
+
 	if (!context.devid) {
 		const char *devid_string = getenv("DEVICE");
 		if (devid_string)
-- 
2.47.3

[PATCH i-g-t 2/4] lib/intel_device_info: add a helper to guess the PCI ID for a codename

[Jani Nikula]

The struct intel_device_info contains the codenames for the
corresponding PCI device IDs. Add a reverse lookup to get a PCI ID for a
codename.

It's a bit fuzzy, though. The codenames aren't always spelled the same,
there are suffixes sometimes omitted, and you can only pick one of the
matching PCI IDs. Name the helper intel_guess_device_id() to emphasize
the point, and try increasing fuzziness in the matching to find an
appropriate struct intel_device_info.

There's nothing exact about this, and it should not be considered as
such. But it will be useful in VBT parsing.

Cc: Michał Grzelak <michal.grzelak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 lib/intel_chipset.h     |  1 +
 lib/intel_device_info.c | 75 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+)

diff --git a/lib/intel_chipset.h b/lib/intel_chipset.h
index 3fcc5b18d648..98a2a81fcffd 100644
--- a/lib/intel_chipset.h
+++ b/lib/intel_chipset.h
@@ -103,6 +103,7 @@ struct intel_device_info {
 };
 
 const struct intel_device_info *intel_get_device_info(uint16_t devid) __attribute__((pure));
+uint16_t intel_guess_device_id(const char *codenameish) __attribute__((pure));
 
 const struct intel_cmds_info *intel_get_cmds_info(uint16_t devid) __attribute__((pure));
 unsigned intel_gen(uint16_t devid) __attribute__((pure));
diff --git a/lib/intel_device_info.c b/lib/intel_device_info.c
index da0b9f398885..3b5373265000 100644
--- a/lib/intel_device_info.c
+++ b/lib/intel_device_info.c
@@ -3,6 +3,7 @@
 #include "i915_pciids_local.h"
 
 #include <strings.h> /* ffs() */
+#include <ctype.h>
 
 static const struct intel_device_info intel_generic_info = {
 	.graphics_ver = 0,
@@ -746,6 +747,80 @@ out:
 	return cache;
 }
 
+static bool char_eq(char c1, char c2)
+{
+	c1 = isalnum(c1) ? tolower(c1) : '-';
+	c2 = isalnum(c2) ? tolower(c2) : '-';
+
+	return c1 == c2;
+}
+
+/*
+ * Return true if the codenames s1 and s2 match, with fuzziness.
+ *
+ * Case insensitive matching, ignoring differences in non-alnum characters. With
+ * non-zero fuzziness, accept matches up to the first non-alnum character.
+ */
+static bool codename_match(const char *s1, const char *s2, int fuzziness)
+{
+	while (*s1 && *s2 && char_eq(*s1, *s2)) {
+		s1++;
+		s2++;
+	}
+
+	/* full match */
+	if (!*s1 && !*s2)
+		return true;
+
+	/* sub-string match up to a non-alnum char */
+	if (fuzziness >=1) {
+		if (!*s1 && !isalnum(*s2))
+			return true;
+		if (!*s2 && !isalnum(*s1))
+			return true;
+	}
+
+	return false;
+}
+
+static uint16_t lookup_device_id(const char *codename, int fuzziness)
+{
+	int i;
+
+	for (i = 0; intel_device_match[i].device_id != PCI_MATCH_ANY; i++) {
+		const struct intel_device_info *info = (void *)intel_device_match[i].match_data;
+
+		if (codename_match(info->codename, codename, fuzziness))
+			return intel_device_match[i].device_id;
+	}
+
+	return 0;
+}
+
+/**
+ * intel_guess_device_id:
+ * @codenameish: something resembling a codename
+ *
+ * Based on something resembling a codename, try to fuzzy find the first PCI
+ * device ID matching the codename.
+ *
+ * Returns:
+ * PCI device ID fuzzy matching the @codenameish, or 0 if no match was found.
+ */
+uint16_t intel_guess_device_id(const char *codenameish)
+{
+	uint16_t devid;
+	int fuzziness;
+
+	for (fuzziness = 0; fuzziness < 2; fuzziness++) {
+		devid = lookup_device_id(codenameish, fuzziness);
+		if (devid)
+			return devid;
+	}
+
+	return 0;
+}
+
 /**
  * intel_get_cmds_info:
  * @devid: pci device id
-- 
2.47.3

[PATCH i-g-t 3/4] tools/vbt_decode: return 0 from get_device_id()

[Jani Nikula]

From: Michał Grzelak <michal.grzelak@intel.com>

This function returns -1 on errors and the caller checks for 0. This
leads to -1 being used as the device id. Return 0 instead of -1.

Signed-off-by: Michał Grzelak <michal.grzelak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 tools/intel_vbt_decode.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/intel_vbt_decode.c b/tools/intel_vbt_decode.c
index 5b39e0c1c33e..69961ce29e01 100644
--- a/tools/intel_vbt_decode.c
+++ b/tools/intel_vbt_decode.c
@@ -3702,13 +3702,13 @@ get_device_id(unsigned char *bios, int size)
     int offset = (bios[0x19] << 8) + bios[0x18];
 
     if (offset + 7 >= size)
-	return -1;
+	return 0;
 
     if (bios[offset] != 'P' ||
 	bios[offset+1] != 'C' ||
 	bios[offset+2] != 'I' ||
 	bios[offset+3] != 'R')
-	return -1;
+	return 0;
 
     device = (bios[offset+7] << 8) + bios[offset+6];
 
-- 
2.47.3

[PATCH i-g-t 4/4] tools/intel_vbt_decode: fall back to guessing PCI ID from VBT signature

[Jani Nikula]

If the PCI ID wasn't passed on the command-line, DEVICE environment
variable, or VBIOS, fall back to guessing the device ID from the VBT
signature.

Cc: Michał Grzelak <michal.grzelak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 tools/intel_vbt_decode.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/intel_vbt_decode.c b/tools/intel_vbt_decode.c
index 69961ce29e01..9451a77318ae 100644
--- a/tools/intel_vbt_decode.c
+++ b/tools/intel_vbt_decode.c
@@ -4331,6 +4331,8 @@ int main(int argc, char **argv)
 	}
 	if (!context.devid)
 		context.devid = get_device_id(VBIOS, size);
+	if (!context.devid)
+		context.devid = intel_guess_device_id(context.codename);
 	if (!context.devid)
 		fprintf(stderr, "Warning: could not find PCI device ID!\n");
 
-- 
2.47.3

✓ Xe.CI.BAT: success for intel_vbt_decode: fall back to guessing PCI ID from VBT signature

[Patchwork]

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== Series Details ==

Series: intel_vbt_decode: fall back to guessing PCI ID from VBT signature
URL   : https://patchwork.freedesktop.org/series/168428/
State : success

== Summary ==

CI Bug Log - changes from XEIGT_8960_BAT -> XEIGTPW_15357_BAT
====================================================

Summary
-------

  **SUCCESS**

  No regressions found.

  

Participating hosts (13 -> 12)
------------------------------

  Missing    (1): bat-lnl-2 


Changes
-------

  No changes found


Build changes
-------------

  * IGT: IGT_8960 -> IGTPW_15357
  * Linux: xe-5244-311cbada9202146752938f54503d33980ee4f3f6 -> xe-5246-9ce63e3d9903982c053b125686abcb7a84357ed4

  IGTPW_15357: 15357
  IGT_8960: 88bd725754990332efcd158b0429f6ac7fb63862 @ https://gitlab.freedesktop.org/drm/igt-gpu-tools.git
  xe-5244-311cbada9202146752938f54503d33980ee4f3f6: 311cbada9202146752938f54503d33980ee4f3f6
  xe-5246-9ce63e3d9903982c053b125686abcb7a84357ed4: 9ce63e3d9903982c053b125686abcb7a84357ed4

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/intel-xe/IGTPW_15357/index.html

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✓ i915.CI.BAT: success for intel_vbt_decode: fall back to guessing PCI ID from VBT signature

[Patchwork]

[-- Attachment #1: Type: text/plain, Size: 1691 bytes --]

== Series Details ==

Series: intel_vbt_decode: fall back to guessing PCI ID from VBT signature
URL   : https://patchwork.freedesktop.org/series/168428/
State : success

== Summary ==

CI Bug Log - changes from IGT_8960 -> IGTPW_15357
====================================================

Summary
-------

  **SUCCESS**

  No regressions found.

  External URL: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_15357/index.html

Participating hosts (42 -> 39)
------------------------------

  Missing    (3): bat-dg2-13 fi-glk-j4005 fi-snb-2520m 

Known issues
------------

  Here are the changes found in IGTPW_15357 that come from known issues:

### IGT changes ###

#### Possible fixes ####

  * igt@kms_hdmi_inject@inject-audio:
    - fi-tgl-1115g4:      [FAIL][1] ([i915#16115]) -> [PASS][2]
   [1]: https://intel-gfx-ci.01.org/tree/drm-tip/IGT_8960/fi-tgl-1115g4/igt@kms_hdmi_inject@inject-audio.html
   [2]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_15357/fi-tgl-1115g4/igt@kms_hdmi_inject@inject-audio.html

  
  [i915#16115]: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/16115


Build changes
-------------

  * CI: CI-20190529 -> None
  * IGT: IGT_8960 -> IGTPW_15357
  * Linux: CI_DRM_18667 -> CI_DRM_18668

  CI-20190529: 20190529
  CI_DRM_18667: d931e7b381f9d86766f3a971a9376e4312745af8 @ git://anongit.freedesktop.org/gfx-ci/linux
  CI_DRM_18668: 9ce63e3d9903982c053b125686abcb7a84357ed4 @ git://anongit.freedesktop.org/gfx-ci/linux
  IGTPW_15357: 15357
  IGT_8960: 88bd725754990332efcd158b0429f6ac7fb63862 @ https://gitlab.freedesktop.org/drm/igt-gpu-tools.git

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_15357/index.html

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Re: [PATCH i-g-t 3/4] tools/vbt_decode: return 0 from get_device_id()

[Kamil Konieczny]

Hi Jani,
On 2026-06-12 at 14:00:43 +0300, Jani Nikula wrote:
> From: Michał Grzelak <michal.grzelak@intel.com>
> 
> This function returns -1 on errors and the caller checks for 0. This
> leads to -1 being used as the device id. Return 0 instead of -1.
> 
LGTM
Reviewed-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>

> Signed-off-by: Michał Grzelak <michal.grzelak@intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  tools/intel_vbt_decode.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/intel_vbt_decode.c b/tools/intel_vbt_decode.c
> index 5b39e0c1c33e..69961ce29e01 100644
> --- a/tools/intel_vbt_decode.c
> +++ b/tools/intel_vbt_decode.c
> @@ -3702,13 +3702,13 @@ get_device_id(unsigned char *bios, int size)
>      int offset = (bios[0x19] << 8) + bios[0x18];

btw do we need a function for this?
like bios_u32(bios, offset) or lowend_u32(p, off)

Regards,
Kamil

>  
>      if (offset + 7 >= size)
> -	return -1;
> +	return 0;
>  
>      if (bios[offset] != 'P' ||
>  	bios[offset+1] != 'C' ||
>  	bios[offset+2] != 'I' ||
>  	bios[offset+3] != 'R')
> -	return -1;
> +	return 0;
>  
>      device = (bios[offset+7] << 8) + bios[offset+6];
>  
> -- 
> 2.47.3
> 

Re: [PATCH i-g-t 2/4] lib/intel_device_info: add a helper to guess the PCI ID for a codename

[Kamil Konieczny]

Hi Jani,
On 2026-06-12 at 14:00:42 +0300, Jani Nikula wrote:
> The struct intel_device_info contains the codenames for the
> corresponding PCI device IDs. Add a reverse lookup to get a PCI ID for a
> codename.
> 
> It's a bit fuzzy, though. The codenames aren't always spelled the same,
> there are suffixes sometimes omitted, and you can only pick one of the
> matching PCI IDs. Name the helper intel_guess_device_id() to emphasize
> the point, and try increasing fuzziness in the matching to find an
> appropriate struct intel_device_info.
> 
> There's nothing exact about this, and it should not be considered as
> such. But it will be useful in VBT parsing.
> 
> Cc: Michał Grzelak <michal.grzelak@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  lib/intel_chipset.h     |  1 +
>  lib/intel_device_info.c | 75 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 76 insertions(+)
> 
> diff --git a/lib/intel_chipset.h b/lib/intel_chipset.h
> index 3fcc5b18d648..98a2a81fcffd 100644
> --- a/lib/intel_chipset.h
> +++ b/lib/intel_chipset.h
> @@ -103,6 +103,7 @@ struct intel_device_info {
>  };
>  
>  const struct intel_device_info *intel_get_device_info(uint16_t devid) __attribute__((pure));
> +uint16_t intel_guess_device_id(const char *codenameish) __attribute__((pure));
>  
>  const struct intel_cmds_info *intel_get_cmds_info(uint16_t devid) __attribute__((pure));
>  unsigned intel_gen(uint16_t devid) __attribute__((pure));
> diff --git a/lib/intel_device_info.c b/lib/intel_device_info.c
> index da0b9f398885..3b5373265000 100644
> --- a/lib/intel_device_info.c
> +++ b/lib/intel_device_info.c
> @@ -3,6 +3,7 @@
>  #include "i915_pciids_local.h"
>  
>  #include <strings.h> /* ffs() */
> +#include <ctype.h>

Move it before strings.h, keep alphabetical order.
Also, all system headers should be before igt ones.

Regards,
Kamil

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