[Intel-gfx] v5.19 & v6.0 stable backport request

[Intel-gfx] v5.19 & v6.0 stable backport request

[Jani Nikula]

Hello stable team, please backport these two commits to stable kernels
v5.19 and v6.0:

4e78d6023c15 ("drm/i915/bios: Validate fp_timing terminator presence")
d3a7051841f0 ("drm/i915/bios: Use hardcoded fp_timing size for generating LFP data pointers")

References: https://lore.kernel.org/r/fac9a564-edff-db25-20d4-7146ae2a7dc8@redhat.com

Thanks,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center

v5.19 & v6.0 stable backport request

[Jani Nikula]

Hello stable team, please backport these two commits to stable kernels
v5.19 and v6.0:

4e78d6023c15 ("drm/i915/bios: Validate fp_timing terminator presence")
d3a7051841f0 ("drm/i915/bios: Use hardcoded fp_timing size for generating LFP data pointers")

References: https://lore.kernel.org/r/fac9a564-edff-db25-20d4-7146ae2a7dc8@redhat.com

Thanks,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: [Intel-gfx] v5.19 & v6.0 stable backport request

[Greg Kroah-Hartman]

On Tue, Oct 18, 2022 at 02:02:08PM +0300, Jani Nikula wrote:
> 
> Hello stable team, please backport these two commits to stable kernels
> v5.19 and v6.0:
> 
> 4e78d6023c15 ("drm/i915/bios: Validate fp_timing terminator presence")

Does not apply to 5.19.y, can you provide a working backport?

> d3a7051841f0 ("drm/i915/bios: Use hardcoded fp_timing size for generating LFP data pointers")

Queued up to both trees now, thanks.

greg k-h

Re: v5.19 & v6.0 stable backport request

[Greg Kroah-Hartman]

On Tue, Oct 18, 2022 at 02:02:08PM +0300, Jani Nikula wrote:
> 
> Hello stable team, please backport these two commits to stable kernels
> v5.19 and v6.0:
> 
> 4e78d6023c15 ("drm/i915/bios: Validate fp_timing terminator presence")

Does not apply to 5.19.y, can you provide a working backport?

> d3a7051841f0 ("drm/i915/bios: Use hardcoded fp_timing size for generating LFP data pointers")

Queued up to both trees now, thanks.

greg k-h

Re: [Intel-gfx] v5.19 & v6.0 stable backport request

[Greg Kroah-Hartman]

On Wed, Oct 19, 2022 at 08:55:55AM +0200, Greg Kroah-Hartman wrote:
> On Tue, Oct 18, 2022 at 02:02:08PM +0300, Jani Nikula wrote:
> > 
> > Hello stable team, please backport these two commits to stable kernels
> > v5.19 and v6.0:
> > 
> > 4e78d6023c15 ("drm/i915/bios: Validate fp_timing terminator presence")
> 
> Does not apply to 5.19.y, can you provide a working backport?
> 
> > d3a7051841f0 ("drm/i915/bios: Use hardcoded fp_timing size for generating LFP data pointers")
> 
> Queued up to both trees now, thanks.

No, wait, that breaks the build!

How did you test this?  I'm dropping both of these now.

Please resubmit a set of tested patches if you wish to have them applied
to the tree.  These were obviously not even attempted, which just wastes
all of our time :(

greg k-h

Re: v5.19 & v6.0 stable backport request

[Greg Kroah-Hartman]

On Wed, Oct 19, 2022 at 08:55:55AM +0200, Greg Kroah-Hartman wrote:
> On Tue, Oct 18, 2022 at 02:02:08PM +0300, Jani Nikula wrote:
> > 
> > Hello stable team, please backport these two commits to stable kernels
> > v5.19 and v6.0:
> > 
> > 4e78d6023c15 ("drm/i915/bios: Validate fp_timing terminator presence")
> 
> Does not apply to 5.19.y, can you provide a working backport?
> 
> > d3a7051841f0 ("drm/i915/bios: Use hardcoded fp_timing size for generating LFP data pointers")
> 
> Queued up to both trees now, thanks.

No, wait, that breaks the build!

How did you test this?  I'm dropping both of these now.

Please resubmit a set of tested patches if you wish to have them applied
to the tree.  These were obviously not even attempted, which just wastes
all of our time :(

greg k-h

Re: [Intel-gfx] v5.19 & v6.0 stable backport request

[Jani Nikula]

On Wed, 19 Oct 2022, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> On Wed, Oct 19, 2022 at 08:55:55AM +0200, Greg Kroah-Hartman wrote:
>> On Tue, Oct 18, 2022 at 02:02:08PM +0300, Jani Nikula wrote:
>> > 
>> > Hello stable team, please backport these two commits to stable kernels
>> > v5.19 and v6.0:
>> > 
>> > 4e78d6023c15 ("drm/i915/bios: Validate fp_timing terminator presence")
>> 
>> Does not apply to 5.19.y, can you provide a working backport?
>> 
>> > d3a7051841f0 ("drm/i915/bios: Use hardcoded fp_timing size for generating LFP data pointers")
>> 
>> Queued up to both trees now, thanks.
>
> No, wait, that breaks the build!
>
> How did you test this?  I'm dropping both of these now.
>
> Please resubmit a set of tested patches if you wish to have them applied
> to the tree.  These were obviously not even attempted, which just wastes
> all of our time :(

Apologies, misunderstanding on my part about them being applicable
as-is.

Ville has provided the backports. Thanks!


BR,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: v5.19 & v6.0 stable backport request

[Jani Nikula]

On Wed, 19 Oct 2022, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> On Wed, Oct 19, 2022 at 08:55:55AM +0200, Greg Kroah-Hartman wrote:
>> On Tue, Oct 18, 2022 at 02:02:08PM +0300, Jani Nikula wrote:
>> > 
>> > Hello stable team, please backport these two commits to stable kernels
>> > v5.19 and v6.0:
>> > 
>> > 4e78d6023c15 ("drm/i915/bios: Validate fp_timing terminator presence")
>> 
>> Does not apply to 5.19.y, can you provide a working backport?
>> 
>> > d3a7051841f0 ("drm/i915/bios: Use hardcoded fp_timing size for generating LFP data pointers")
>> 
>> Queued up to both trees now, thanks.
>
> No, wait, that breaks the build!
>
> How did you test this?  I'm dropping both of these now.
>
> Please resubmit a set of tested patches if you wish to have them applied
> to the tree.  These were obviously not even attempted, which just wastes
> all of our time :(

Apologies, misunderstanding on my part about them being applicable
as-is.

Ville has provided the backports. Thanks!


BR,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center

[Intel-gfx] [PATCH stable-5.19+ 1/2] drm/i915/bios: Validate fp_timing terminator presence

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Validate the LFP data block a bit hardwer by making sure the
fp_timing terminators (0xffff) are where we expect them to be.

Cc: <stable@vger.kernel.org> # 5.19.x: 39b1bc4b5bcc: drm/i915: Rename block_size()/block_offset()
Cc: <stable@vger.kernel.org> # 5.19+
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220818192223.29881-2-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit 4e78d6023c15c6acce8fbe42e13027c460395522)
---
 drivers/gpu/drm/i915/display/intel_bios.c | 60 ++++++++++++-----------
 1 file changed, 32 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index 7d6eb9ad7a02..1a30e645c5a7 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -135,18 +135,6 @@ static u32 raw_block_offset(const void *bdb, enum bdb_block_id section_id)
 	return block - bdb;
 }
 
-/* size of the block excluding the header */
-static u32 raw_block_size(const void *bdb, enum bdb_block_id section_id)
-{
-	const void *block;
-
-	block = find_raw_section(bdb, section_id);
-	if (!block)
-		return 0;
-
-	return get_blocksize(block);
-}
-
 struct bdb_block_entry {
 	struct list_head node;
 	enum bdb_block_id section_id;
@@ -231,9 +219,14 @@ static bool validate_lfp_data_ptrs(const void *bdb,
 {
 	int fp_timing_size, dvo_timing_size, panel_pnp_id_size, panel_name_size;
 	int data_block_size, lfp_data_size;
+	const void *data_block;
 	int i;
 
-	data_block_size = raw_block_size(bdb, BDB_LVDS_LFP_DATA);
+	data_block = find_raw_section(bdb, BDB_LVDS_LFP_DATA);
+	if (!data_block)
+		return false;
+
+	data_block_size = get_blocksize(data_block);
 	if (data_block_size == 0)
 		return false;
 
@@ -261,21 +254,6 @@ static bool validate_lfp_data_ptrs(const void *bdb,
 	if (16 * lfp_data_size > data_block_size)
 		return false;
 
-	/*
-	 * Except for vlv/chv machines all real VBTs seem to have 6
-	 * unaccounted bytes in the fp_timing table. And it doesn't
-	 * appear to be a really intentional hole as the fp_timing
-	 * 0xffff terminator is always within those 6 missing bytes.
-	 */
-	if (fp_timing_size + dvo_timing_size + panel_pnp_id_size != lfp_data_size &&
-	    fp_timing_size + 6 + dvo_timing_size + panel_pnp_id_size != lfp_data_size)
-		return false;
-
-	if (ptrs->ptr[0].fp_timing.offset + fp_timing_size > ptrs->ptr[0].dvo_timing.offset ||
-	    ptrs->ptr[0].dvo_timing.offset + dvo_timing_size != ptrs->ptr[0].panel_pnp_id.offset ||
-	    ptrs->ptr[0].panel_pnp_id.offset + panel_pnp_id_size != lfp_data_size)
-		return false;
-
 	/* make sure the table entries have uniform size */
 	for (i = 1; i < 16; i++) {
 		if (ptrs->ptr[i].fp_timing.table_size != fp_timing_size ||
@@ -289,6 +267,23 @@ static bool validate_lfp_data_ptrs(const void *bdb,
 			return false;
 	}
 
+	/*
+	 * Except for vlv/chv machines all real VBTs seem to have 6
+	 * unaccounted bytes in the fp_timing table. And it doesn't
+	 * appear to be a really intentional hole as the fp_timing
+	 * 0xffff terminator is always within those 6 missing bytes.
+	 */
+	if (fp_timing_size + 6 + dvo_timing_size + panel_pnp_id_size == lfp_data_size)
+		fp_timing_size += 6;
+
+	if (fp_timing_size + dvo_timing_size + panel_pnp_id_size != lfp_data_size)
+		return false;
+
+	if (ptrs->ptr[0].fp_timing.offset + fp_timing_size != ptrs->ptr[0].dvo_timing.offset ||
+	    ptrs->ptr[0].dvo_timing.offset + dvo_timing_size != ptrs->ptr[0].panel_pnp_id.offset ||
+	    ptrs->ptr[0].panel_pnp_id.offset + panel_pnp_id_size != lfp_data_size)
+		return false;
+
 	/* make sure the tables fit inside the data block */
 	for (i = 0; i < 16; i++) {
 		if (ptrs->ptr[i].fp_timing.offset + fp_timing_size > data_block_size ||
@@ -300,6 +295,15 @@ static bool validate_lfp_data_ptrs(const void *bdb,
 	if (ptrs->panel_name.offset + 16 * panel_name_size > data_block_size)
 		return false;
 
+	/* make sure fp_timing terminators are present at expected locations */
+	for (i = 0; i < 16; i++) {
+		const u16 *t = data_block + ptrs->ptr[i].fp_timing.offset +
+			fp_timing_size - 2;
+
+		if (*t != 0xffff)
+			return false;
+	}
+
 	return true;
 }
 
-- 
2.35.1

[PATCH stable-5.19+ 1/2] drm/i915/bios: Validate fp_timing terminator presence

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Validate the LFP data block a bit hardwer by making sure the
fp_timing terminators (0xffff) are where we expect them to be.

Cc: <stable@vger.kernel.org> # 5.19.x: 39b1bc4b5bcc: drm/i915: Rename block_size()/block_offset()
Cc: <stable@vger.kernel.org> # 5.19+
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220818192223.29881-2-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit 4e78d6023c15c6acce8fbe42e13027c460395522)
---
 drivers/gpu/drm/i915/display/intel_bios.c | 60 ++++++++++++-----------
 1 file changed, 32 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index 7d6eb9ad7a02..1a30e645c5a7 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -135,18 +135,6 @@ static u32 raw_block_offset(const void *bdb, enum bdb_block_id section_id)
 	return block - bdb;
 }
 
-/* size of the block excluding the header */
-static u32 raw_block_size(const void *bdb, enum bdb_block_id section_id)
-{
-	const void *block;
-
-	block = find_raw_section(bdb, section_id);
-	if (!block)
-		return 0;
-
-	return get_blocksize(block);
-}
-
 struct bdb_block_entry {
 	struct list_head node;
 	enum bdb_block_id section_id;
@@ -231,9 +219,14 @@ static bool validate_lfp_data_ptrs(const void *bdb,
 {
 	int fp_timing_size, dvo_timing_size, panel_pnp_id_size, panel_name_size;
 	int data_block_size, lfp_data_size;
+	const void *data_block;
 	int i;
 
-	data_block_size = raw_block_size(bdb, BDB_LVDS_LFP_DATA);
+	data_block = find_raw_section(bdb, BDB_LVDS_LFP_DATA);
+	if (!data_block)
+		return false;
+
+	data_block_size = get_blocksize(data_block);
 	if (data_block_size == 0)
 		return false;
 
@@ -261,21 +254,6 @@ static bool validate_lfp_data_ptrs(const void *bdb,
 	if (16 * lfp_data_size > data_block_size)
 		return false;
 
-	/*
-	 * Except for vlv/chv machines all real VBTs seem to have 6
-	 * unaccounted bytes in the fp_timing table. And it doesn't
-	 * appear to be a really intentional hole as the fp_timing
-	 * 0xffff terminator is always within those 6 missing bytes.
-	 */
-	if (fp_timing_size + dvo_timing_size + panel_pnp_id_size != lfp_data_size &&
-	    fp_timing_size + 6 + dvo_timing_size + panel_pnp_id_size != lfp_data_size)
-		return false;
-
-	if (ptrs->ptr[0].fp_timing.offset + fp_timing_size > ptrs->ptr[0].dvo_timing.offset ||
-	    ptrs->ptr[0].dvo_timing.offset + dvo_timing_size != ptrs->ptr[0].panel_pnp_id.offset ||
-	    ptrs->ptr[0].panel_pnp_id.offset + panel_pnp_id_size != lfp_data_size)
-		return false;
-
 	/* make sure the table entries have uniform size */
 	for (i = 1; i < 16; i++) {
 		if (ptrs->ptr[i].fp_timing.table_size != fp_timing_size ||
@@ -289,6 +267,23 @@ static bool validate_lfp_data_ptrs(const void *bdb,
 			return false;
 	}
 
+	/*
+	 * Except for vlv/chv machines all real VBTs seem to have 6
+	 * unaccounted bytes in the fp_timing table. And it doesn't
+	 * appear to be a really intentional hole as the fp_timing
+	 * 0xffff terminator is always within those 6 missing bytes.
+	 */
+	if (fp_timing_size + 6 + dvo_timing_size + panel_pnp_id_size == lfp_data_size)
+		fp_timing_size += 6;
+
+	if (fp_timing_size + dvo_timing_size + panel_pnp_id_size != lfp_data_size)
+		return false;
+
+	if (ptrs->ptr[0].fp_timing.offset + fp_timing_size != ptrs->ptr[0].dvo_timing.offset ||
+	    ptrs->ptr[0].dvo_timing.offset + dvo_timing_size != ptrs->ptr[0].panel_pnp_id.offset ||
+	    ptrs->ptr[0].panel_pnp_id.offset + panel_pnp_id_size != lfp_data_size)
+		return false;
+
 	/* make sure the tables fit inside the data block */
 	for (i = 0; i < 16; i++) {
 		if (ptrs->ptr[i].fp_timing.offset + fp_timing_size > data_block_size ||
@@ -300,6 +295,15 @@ static bool validate_lfp_data_ptrs(const void *bdb,
 	if (ptrs->panel_name.offset + 16 * panel_name_size > data_block_size)
 		return false;
 
+	/* make sure fp_timing terminators are present at expected locations */
+	for (i = 0; i < 16; i++) {
+		const u16 *t = data_block + ptrs->ptr[i].fp_timing.offset +
+			fp_timing_size - 2;
+
+		if (*t != 0xffff)
+			return false;
+	}
+
 	return true;
 }
 
-- 
2.35.1

[Intel-gfx] [PATCH stable-5.19+ 2/2] drm/i915/bios: Use hardcoded fp_timing size for generating LFP data pointers

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

The current scheme for generating the LFP data table pointers
(when the block including them is missing from the VBT) expects
the 0xffff sequence to only appear in the fp_timing terminator
entries. However some VBTs also have extra 0xffff sequences
elsewhere in the LFP data. When looking for the terminators
we may end up finding those extra sequeneces insted, which means
we deduce the wrong size for the fp_timing table. The code
then notices the inconsistent looking values and gives up on
the generated data table pointers, preventing us from parsing
the LFP data table entirely.

Let's give up on the "search for the terminators" approach
and instead just hardcode the expected size for the fp_timing
table.

We have enough sanity checks in place to make sure we
shouldn't end up parsing total garbage even if that size
should change in the future (although that seems unlikely
as the fp_timing and dvo_timing tables have been declared
obsolete as of VBT version 229).

Cc: <stable@vger.kernel.org> # 5.19+
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6592
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220818192223.29881-3-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit d3a7051841f0a4bcb1ee26a1b721c6150cc4c2b1)
---
 drivers/gpu/drm/i915/display/intel_bios.c | 46 +++++++++--------------
 1 file changed, 18 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index 1a30e645c5a7..459571e2cc57 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -337,18 +337,6 @@ static bool fixup_lfp_data_ptrs(const void *bdb, void *ptrs_block)
 	return validate_lfp_data_ptrs(bdb, ptrs);
 }
 
-static const void *find_fp_timing_terminator(const u8 *data, int size)
-{
-	int i;
-
-	for (i = 0; i < size - 1; i++) {
-		if (data[i] == 0xff && data[i+1] == 0xff)
-			return &data[i];
-	}
-
-	return NULL;
-}
-
 static int make_lfp_data_ptr(struct lvds_lfp_data_ptr_table *table,
 			     int table_size, int total_size)
 {
@@ -372,11 +360,22 @@ static void next_lfp_data_ptr(struct lvds_lfp_data_ptr_table *next,
 static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
 				    const void *bdb)
 {
-	int i, size, table_size, block_size, offset;
-	const void *t0, *t1, *block;
+	int i, size, table_size, block_size, offset, fp_timing_size;
 	struct bdb_lvds_lfp_data_ptrs *ptrs;
+	const void *block;
 	void *ptrs_block;
 
+	/*
+	 * The hardcoded fp_timing_size is only valid for
+	 * modernish VBTs. All older VBTs definitely should
+	 * include block 41 and thus we don't need to
+	 * generate one.
+	 */
+	if (i915->vbt.version < 155)
+		return NULL;
+
+	fp_timing_size = 38;
+
 	block = find_raw_section(bdb, BDB_LVDS_LFP_DATA);
 	if (!block)
 		return NULL;
@@ -385,17 +384,8 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
 
 	block_size = get_blocksize(block);
 
-	size = block_size;
-	t0 = find_fp_timing_terminator(block, size);
-	if (!t0)
-		return NULL;
-
-	size -= t0 - block - 2;
-	t1 = find_fp_timing_terminator(t0 + 2, size);
-	if (!t1)
-		return NULL;
-
-	size = t1 - t0;
+	size = fp_timing_size + sizeof(struct lvds_dvo_timing) +
+		sizeof(struct lvds_pnp_id);
 	if (size * 16 > block_size)
 		return NULL;
 
@@ -413,7 +403,7 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
 	table_size = sizeof(struct lvds_dvo_timing);
 	size = make_lfp_data_ptr(&ptrs->ptr[0].dvo_timing, table_size, size);
 
-	table_size = t0 - block + 2;
+	table_size = fp_timing_size;
 	size = make_lfp_data_ptr(&ptrs->ptr[0].fp_timing, table_size, size);
 
 	if (ptrs->ptr[0].fp_timing.table_size)
@@ -428,14 +418,14 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
 		return NULL;
 	}
 
-	size = t1 - t0;
+	size = fp_timing_size + sizeof(struct lvds_dvo_timing) +
+		sizeof(struct lvds_pnp_id);
 	for (i = 1; i < 16; i++) {
 		next_lfp_data_ptr(&ptrs->ptr[i].fp_timing, &ptrs->ptr[i-1].fp_timing, size);
 		next_lfp_data_ptr(&ptrs->ptr[i].dvo_timing, &ptrs->ptr[i-1].dvo_timing, size);
 		next_lfp_data_ptr(&ptrs->ptr[i].panel_pnp_id, &ptrs->ptr[i-1].panel_pnp_id, size);
 	}
 
-	size = t1 - t0;
 	table_size = sizeof(struct lvds_lfp_panel_name);
 
 	if (16 * (size + table_size) <= block_size) {
-- 
2.35.1

[PATCH stable-5.19+ 2/2] drm/i915/bios: Use hardcoded fp_timing size for generating LFP data pointers

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

The current scheme for generating the LFP data table pointers
(when the block including them is missing from the VBT) expects
the 0xffff sequence to only appear in the fp_timing terminator
entries. However some VBTs also have extra 0xffff sequences
elsewhere in the LFP data. When looking for the terminators
we may end up finding those extra sequeneces insted, which means
we deduce the wrong size for the fp_timing table. The code
then notices the inconsistent looking values and gives up on
the generated data table pointers, preventing us from parsing
the LFP data table entirely.

Let's give up on the "search for the terminators" approach
and instead just hardcode the expected size for the fp_timing
table.

We have enough sanity checks in place to make sure we
shouldn't end up parsing total garbage even if that size
should change in the future (although that seems unlikely
as the fp_timing and dvo_timing tables have been declared
obsolete as of VBT version 229).

Cc: <stable@vger.kernel.org> # 5.19+
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6592
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220818192223.29881-3-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit d3a7051841f0a4bcb1ee26a1b721c6150cc4c2b1)
---
 drivers/gpu/drm/i915/display/intel_bios.c | 46 +++++++++--------------
 1 file changed, 18 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index 1a30e645c5a7..459571e2cc57 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -337,18 +337,6 @@ static bool fixup_lfp_data_ptrs(const void *bdb, void *ptrs_block)
 	return validate_lfp_data_ptrs(bdb, ptrs);
 }
 
-static const void *find_fp_timing_terminator(const u8 *data, int size)
-{
-	int i;
-
-	for (i = 0; i < size - 1; i++) {
-		if (data[i] == 0xff && data[i+1] == 0xff)
-			return &data[i];
-	}
-
-	return NULL;
-}
-
 static int make_lfp_data_ptr(struct lvds_lfp_data_ptr_table *table,
 			     int table_size, int total_size)
 {
@@ -372,11 +360,22 @@ static void next_lfp_data_ptr(struct lvds_lfp_data_ptr_table *next,
 static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
 				    const void *bdb)
 {
-	int i, size, table_size, block_size, offset;
-	const void *t0, *t1, *block;
+	int i, size, table_size, block_size, offset, fp_timing_size;
 	struct bdb_lvds_lfp_data_ptrs *ptrs;
+	const void *block;
 	void *ptrs_block;
 
+	/*
+	 * The hardcoded fp_timing_size is only valid for
+	 * modernish VBTs. All older VBTs definitely should
+	 * include block 41 and thus we don't need to
+	 * generate one.
+	 */
+	if (i915->vbt.version < 155)
+		return NULL;
+
+	fp_timing_size = 38;
+
 	block = find_raw_section(bdb, BDB_LVDS_LFP_DATA);
 	if (!block)
 		return NULL;
@@ -385,17 +384,8 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
 
 	block_size = get_blocksize(block);
 
-	size = block_size;
-	t0 = find_fp_timing_terminator(block, size);
-	if (!t0)
-		return NULL;
-
-	size -= t0 - block - 2;
-	t1 = find_fp_timing_terminator(t0 + 2, size);
-	if (!t1)
-		return NULL;
-
-	size = t1 - t0;
+	size = fp_timing_size + sizeof(struct lvds_dvo_timing) +
+		sizeof(struct lvds_pnp_id);
 	if (size * 16 > block_size)
 		return NULL;
 
@@ -413,7 +403,7 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
 	table_size = sizeof(struct lvds_dvo_timing);
 	size = make_lfp_data_ptr(&ptrs->ptr[0].dvo_timing, table_size, size);
 
-	table_size = t0 - block + 2;
+	table_size = fp_timing_size;
 	size = make_lfp_data_ptr(&ptrs->ptr[0].fp_timing, table_size, size);
 
 	if (ptrs->ptr[0].fp_timing.table_size)
@@ -428,14 +418,14 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
 		return NULL;
 	}
 
-	size = t1 - t0;
+	size = fp_timing_size + sizeof(struct lvds_dvo_timing) +
+		sizeof(struct lvds_pnp_id);
 	for (i = 1; i < 16; i++) {
 		next_lfp_data_ptr(&ptrs->ptr[i].fp_timing, &ptrs->ptr[i-1].fp_timing, size);
 		next_lfp_data_ptr(&ptrs->ptr[i].dvo_timing, &ptrs->ptr[i-1].dvo_timing, size);
 		next_lfp_data_ptr(&ptrs->ptr[i].panel_pnp_id, &ptrs->ptr[i-1].panel_pnp_id, size);
 	}
 
-	size = t1 - t0;
 	table_size = sizeof(struct lvds_lfp_panel_name);
 
 	if (16 * (size + table_size) <= block_size) {
-- 
2.35.1