HDLCD crashes with 6d910bfa809e

[Marek Szyprowski]

Hi All,


On 2016-06-07 16:34, liviu.dudau at arm.com wrote:
> On Tue, Jun 07, 2016 at 03:11:14PM +0100, Robin Murphy wrote:
>> Hi Liviu,
>>
>> On 07/06/16 14:35, liviu.dudau at arm.com wrote:
>>> On Tue, Jun 07, 2016 at 01:06:00PM +0100, Robin Murphy wrote:
>>>> Having just inadvertently merged -next into my working branch, I find
>>>> dev6d910bfa809e ("drm/hlcd: Use lockless gem BO free callback") adversely
>>>> affecting my board's ability to boot ;)
>>>>
>>>> Since I (intentionally) don't have sufficient CMA to create a framebuffer,
>>>> drm_gem_cma_create() fails, unconditionally calls the now-NULL
>>>> drm->driver->gem_free_object() in its cleanup path, and fiery death
>>>> ensues...
>>> Thanks for reporting this. What other changes other than reducing the CMA
>>> allocation size do you have that I might need in order to reproduce this?
>> I've just confirmed a plain checkout of next-20160602, using arm64 defconfig
>> + DRM + HDLCD + TDA998X and CMA_SIZE_MBYTES=1, booted on a Juno, does the
>> job:
>>
>> [    3.032402] hdlcd 7ff60000.hdlcd: bound 0-0070 (ops tda998x_ops)
>> [    3.038388] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
>> [    3.044970] [drm] No driver support for vblank timestamp query.
>> [    3.076973] hdlcd 7ff60000.hdlcd: failed to allocate buffer with size
>> 7680000
>> [    3.084081] Bad mode in Synchronous Abort handler detected, code
>> 0x86000004 -- IABT (current EL)
>> [    3.092815] CPU: 3 PID: 6 Comm: kworker/u12:0 Not tainted
>> 4.7.0-rc1-next-20160602 #686
>> [    3.100682] Hardware name: ARM Juno development board (r1) (DT)
>> [    3.106567] Workqueue: deferwq deferred_probe_work_func
>> [    3.111761] task: ffff8009768a3e80 ti: ffff8009768e8000 task.ti:
>> ffff8009768e8000
>> [    3.119198] PC is at 0x0
>> [    3.121720] LR is at drm_gem_cma_create+0x128/0x130
>> ...and so on.
>>
>> Today's -next, on the other hand, dodges the bullet entirely:
>>
>> [    2.903645] [drm] found ARM HDLCD version r0p0
>> [    2.908122] hdlcd 7ff60000.hdlcd: master bind failed: -22
>> [    2.913505] tda998x: probe of 0-0070 failed with error -22
>> [    2.919141] [drm] found ARM HDLCD version r0p0
>> [    2.923609] hdlcd 7ff50000.hdlcd: master bind failed: -22
>> [    2.928991] tda998x: probe of 0-0071 failed with error -22
> OK, the problem is that commit 59ce4039727ef40 has changed the behaviour from when
> there is no "memory-region" phandle in the DT: before it used to return -ENODEV, now
> it returns -EINVAL.
>
> Marek, I quite liked the old behaviour to detect if the DT had the optional (from
> my driver's point of view) "memory-region" phandle. Plus the check for dev is superfluous
> when using of_reserved_mem_device_init() as that uses dev->of_node for np so it would
> crash before the check anyway. Maybe move the check there?
>
> Until then I suggest reverting the 59ce4039727ef40 commit.

I've just send a fix for this issue. I'm sorry for the regression. I 
hope the fix fill
quickly get into next to solve your problem.

The additional check for null dev make sense, because the new function
of_reserved_mem_device_init_by_idx can be called with any device and 
node pointer not
embedded with it, so I would like to keep it safe.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland