[Intel-gfx] [PATCH] drm/i915: Fix not finding the VBT when it overlaps with OPREGION_ASLE_EXT

[Hans de Goede]

Hi,

On 31-12-16 17:00, Hans de Goede wrote:
> Hi,
>
> On 27-12-16 11:58, Jani Nikula wrote:
>> On Sun, 25 Dec 2016, Hans de Goede <hdegoede at redhat.com> wrote:
>>> If there is no OPREGION_ASLE_EXT then a VBT stored in mailbox #4 may
>>> use the ASLE_EXT parts of the opregion. Adjust the vbt_size calculation
>>> for a vbt in mailbox #4 for this.
>>>
>>> This fixes the driver not finding the VBT on a jumper ezpad mini3
>>> cherrytrail tablet.
>>
>> Thanks for the patch. I think you're onto something, but I don't think
>> the patch is quite correct. That said, I'm not sure myself yet what
>> would be. ;)
>>
>> Without the change, does intel_bios_is_valid_vbt() return true anyway?
>
> No.
>
>> I.e. do you get "Found valid VBT in ACPI OpRegion (Mailbox #4)\n" in
>> log?
>
> No.
>
>> If not, which of the debug messages in intel_bios_is_valid_vbt() do
>> you get?
>
> I get "BDB incomplete", which is why I wrote this patch and believe
> this patch is the right solution. With this patch everything works,
>
>> In the latter case, I suspect you'll end up with failure in intel_bios.c
>> with either "No MIPI config BDB found" or "No MIPI Sequence found,
>> parsing complete\n".
>
> I don't remember the exact error, other then getting the
> "BDB incomplete" error, and the i915 driver not listing the DSI connector
> under /sys/class drm.
>
> What makes you say: "but I don't think the patch is quite correct" why
> should the code still keep the OPREGION_ASLE_EXT start as end of the
> mailbox #4 vbt if there is the ASLE extenstion is not used ?

Ping, any progress on this ? I still believe my original patch is
correct. Eitherway I would like to see a fix for this, be it this fix
or something else, as a fix is necessary to get the LCD panel to work
on jumper ezpad mini3 tablets.

Regards,

Hans



>>> Cc: stable at vger.kernel.org
>>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>>> ---
>>> Note even with this fixed the panel still does not work with 4.9,
>>> but it does with drm-intel-next-queued :) I believe the missing bit in
>>> 4.9 is the "drm/915: Parsing the missed out DTD fields from the VBT"
>>> commit, but I've not verified this.
>>> ---
>>>  drivers/gpu/drm/i915/intel_opregion.c | 4 +++-
>>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
>>> index f4429f6..eff35ae 100644
>>> --- a/drivers/gpu/drm/i915/intel_opregion.c
>>> +++ b/drivers/gpu/drm/i915/intel_opregion.c
>>> @@ -982,7 +982,9 @@ int intel_opregion_setup(struct drm_i915_private *dev_priv)
>>>              opregion->vbt_size = vbt_size;
>>>          } else {
>>>              vbt = base + OPREGION_VBT_OFFSET;
>>> -            vbt_size = OPREGION_ASLE_EXT_OFFSET - OPREGION_VBT_OFFSET;
>>> +            vbt_size = (mboxes & MBOX_ASLE_EXT) ?
>>> +                OPREGION_ASLE_EXT_OFFSET : OPREGION_SIZE;
>>> +            vbt_size -= OPREGION_VBT_OFFSET;
>>>              if (intel_bios_is_valid_vbt(vbt, vbt_size)) {
>>>                  DRM_DEBUG_KMS("Found valid VBT in ACPI OpRegion (Mailbox #4)\n");
>>>                  opregion->vbt = vbt;
>>