* [PATCH] drm/edid: Fix parsing of EDID 1.4 Established Timings III descriptor
@ 2016-03-27 11:15 Paul Parsons
2016-03-30 10:10 ` Jani Nikula
0 siblings, 1 reply; 6+ messages in thread
From: Paul Parsons @ 2016-03-27 11:15 UTC (permalink / raw)
To: dri-devel
The EDID 1.4 specification section 3.10.3.9 defines an Established Timings III
descriptor (tag #F7h). The parsing of this descriptor by drm_est3_modes() is
off by one byte: the offset of the first timing bitmap is 6, not 5.
Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
---
diff -ru a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
--- a/drivers/gpu/drm/drm_edid.c 2016-03-14 04:28:54.000000000 +0000
+++ b/drivers/gpu/drm/drm_edid.c 2016-03-26 12:04:58.963352156 +0000
@@ -2215,7 +2215,7 @@
{
int i, j, m, modes = 0;
struct drm_display_mode *mode;
- u8 *est = ((u8 *)timing) + 5;
+ u8 *est = ((u8 *)timing) + 6;
for (i = 0; i < 6; i++) {
for (j = 7; j >= 0; j--) {
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^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH] drm/edid: Fix parsing of EDID 1.4 Established Timings III descriptor
@ 2016-03-26 13:18 Paul Parsons
2016-03-30 9:45 ` Jani Nikula
2016-03-30 13:19 ` Ville Syrjälä
0 siblings, 2 replies; 6+ messages in thread
From: Paul Parsons @ 2016-03-26 13:18 UTC (permalink / raw)
To: dri-devel
The EDID 1.4 specification section 3.10.3.9 defines an Established Timings III
descriptor (tag #F7h). The parsing of this descriptor by drm_est3_modes() is
off by one byte: the offset of the first timing bitmap is 6, not 5.
Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
---
diff -ru a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
--- a/drivers/gpu/drm/drm_edid.c 2016-03-14 04:28:54.000000000 +0000
+++ b/drivers/gpu/drm/drm_edid.c 2016-03-26 12:04:58.963352156 +0000
@@ -2215,7 +2215,7 @@
{
int i, j, m, modes = 0;
struct drm_display_mode *mode;
- u8 *est = ((u8 *)timing) + 5;
+ u8 *est = ((u8 *)timing) + 6;
for (i = 0; i < 6; i++) {
for (j = 7; j >= 0; j--) {
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] drm/edid: Fix parsing of EDID 1.4 Established Timings III descriptor
2016-03-26 13:18 Paul Parsons
@ 2016-03-30 9:45 ` Jani Nikula
2016-03-30 13:19 ` Ville Syrjälä
1 sibling, 0 replies; 6+ messages in thread
From: Jani Nikula @ 2016-03-30 9:45 UTC (permalink / raw)
To: Paul Parsons, dri-devel
On Sat, 26 Mar 2016, Paul Parsons <lost.distance@yahoo.com> wrote:
> The EDID 1.4 specification section 3.10.3.9 defines an Established Timings III
> descriptor (tag #F7h). The parsing of this descriptor by drm_est3_modes() is
> off by one byte: the offset of the first timing bitmap is 6, not 5.
>
> Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
I'm not all that familiar with the EDID parsing code, but this seems
right.
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
I'd appreciate an extra set of eyeballs on this one still.
Makes you wonder about the implications though. We've been reading the
revision number as a bitmask and otherwise been off by one byte. The
interpretation of Established Timings III would have been pretty much
random. Where are the bugs?
BR,
Jani.
> ---
>
> diff -ru a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> --- a/drivers/gpu/drm/drm_edid.c 2016-03-14 04:28:54.000000000 +0000
> +++ b/drivers/gpu/drm/drm_edid.c 2016-03-26 12:04:58.963352156 +0000
> @@ -2215,7 +2215,7 @@
> {
> int i, j, m, modes = 0;
> struct drm_display_mode *mode;
> - u8 *est = ((u8 *)timing) + 5;
> + u8 *est = ((u8 *)timing) + 6;
>
> for (i = 0; i < 6; i++) {
> for (j = 7; j >= 0; j--) {
>
>
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Jani Nikula, Intel Open Source Technology Center
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] drm/edid: Fix parsing of EDID 1.4 Established Timings III descriptor
2016-03-26 13:18 Paul Parsons
2016-03-30 9:45 ` Jani Nikula
@ 2016-03-30 13:19 ` Ville Syrjälä
2016-04-05 10:27 ` Jani Nikula
1 sibling, 1 reply; 6+ messages in thread
From: Ville Syrjälä @ 2016-03-30 13:19 UTC (permalink / raw)
To: Paul Parsons; +Cc: dri-devel
On Sat, Mar 26, 2016 at 01:18:38PM +0000, Paul Parsons wrote:
> The EDID 1.4 specification section 3.10.3.9 defines an Established Timings III
> descriptor (tag #F7h). The parsing of this descriptor by drm_est3_modes() is
> off by one byte: the offset of the first timing bitmap is 6, not 5.
>
> Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
> ---
>
> diff -ru a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> --- a/drivers/gpu/drm/drm_edid.c 2016-03-14 04:28:54.000000000 +0000
> +++ b/drivers/gpu/drm/drm_edid.c 2016-03-26 12:04:58.963352156 +0000
> @@ -2215,7 +2215,7 @@
> {
> int i, j, m, modes = 0;
> struct drm_display_mode *mode;
> - u8 *est = ((u8 *)timing) + 5;
> + u8 *est = ((u8 *)timing) + 6;
Hmm. The code is very hard to follow due to the weird structs and
whatnot. But yeah this looks correct.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Oh and I suppose you could also fix up the EDID version check
to check for 1.4+ before even considering the est3 descriptor
as valid.
>
> for (i = 0; i < 6; i++) {
> for (j = 7; j >= 0; j--) {
>
>
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Ville Syrjälä
Intel OTC
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] drm/edid: Fix parsing of EDID 1.4 Established Timings III descriptor
2016-03-30 13:19 ` Ville Syrjälä
@ 2016-04-05 10:27 ` Jani Nikula
0 siblings, 0 replies; 6+ messages in thread
From: Jani Nikula @ 2016-04-05 10:27 UTC (permalink / raw)
To: Ville Syrjälä, Paul Parsons; +Cc: dri-devel
On Wed, 30 Mar 2016, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Sat, Mar 26, 2016 at 01:18:38PM +0000, Paul Parsons wrote:
>> The EDID 1.4 specification section 3.10.3.9 defines an Established Timings III
>> descriptor (tag #F7h). The parsing of this descriptor by drm_est3_modes() is
>> off by one byte: the offset of the first timing bitmap is 6, not 5.
>>
>> Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
>> ---
>>
>> diff -ru a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
>> --- a/drivers/gpu/drm/drm_edid.c 2016-03-14 04:28:54.000000000 +0000
>> +++ b/drivers/gpu/drm/drm_edid.c 2016-03-26 12:04:58.963352156 +0000
>> @@ -2215,7 +2215,7 @@
>> {
>> int i, j, m, modes = 0;
>> struct drm_display_mode *mode;
>> - u8 *est = ((u8 *)timing) + 5;
>> + u8 *est = ((u8 *)timing) + 6;
>
> Hmm. The code is very hard to follow due to the weird structs and
> whatnot. But yeah this looks correct.
>
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Pushed to our topic/drm-fixes, thanks for the patch and review.
BR,
Jani.
>
> Oh and I suppose you could also fix up the EDID version check
> to check for 1.4+ before even considering the est3 descriptor
> as valid.
>
>>
>> for (i = 0; i < 6; i++) {
>> for (j = 7; j >= 0; j--) {
>>
>>
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Jani Nikula, Intel Open Source Technology Center
_______________________________________________
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https://lists.freedesktop.org/mailman/listinfo/dri-devel
^ permalink raw reply [flat|nested] 6+ messages in thread
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2016-03-27 11:15 [PATCH] drm/edid: Fix parsing of EDID 1.4 Established Timings III descriptor Paul Parsons
2016-03-30 10:10 ` Jani Nikula
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2016-03-26 13:18 Paul Parsons
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2016-03-30 13:19 ` Ville Syrjälä
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