[PATCH 13/14] drm/msm/dp: move next_bridge handling to dp_display

[Kuogee Hsieh]

On 1/22/2024 4:23 PM, Dmitry Baryshkov wrote:
> On Tue, 23 Jan 2024 at 01:20, Kuogee Hsieh <quic_khsieh at quicinc.com> wrote:
>>
>> On 1/22/2024 9:28 AM, Kuogee Hsieh wrote:
>>> On 1/19/2024 6:31 PM, Dmitry Baryshkov wrote:
>>>> On Fri, 19 Jan 2024 at 23:14, Kuogee Hsieh <quic_khsieh at quicinc.com>
>>>> wrote:
>>>>> Dmitry,
>>>>>
>>>>> I am testing this patch serial with msm-next branch.
>>>>>
>>>>> This patch cause system crash during booting up for me.
>>>>>
>>>>> Is this patch work for you?
>>>> Yes, tested on top of linux-next. However I only tested it with
>>>> DP-over-USBC. What is your testcase? Could you please share the crash
>>>> log?
>>> I tested it on chrome device (sc7280) which has eDP as primary and
>>> without external USBC DP connected.
>>>
>>> It crashes during boot.
>>>
>>> I will debug it more and collect logs for you.
>>>
>> Below  patch work for chrome with both eDP and external DP.
>>
>> We have to return failed if it is the external DP and return value of
>> devm_drm_of_get_bridge()  is !ENODEV since DP does not have next bridge.
>>
>> Otherwise should continues to component_add()
> We also should not continue if it is eDP in case of any error.
>
> So it is if (is_edp || (!is_edp && ret != -ENODEV)) which is exactly
> equivalent to (is_edp || ret != -ENODEV).

yes, you are correct.

I just found that the real fix of crash is "+ dp->next_bridge = NULL;" 
since dp->next_bridge will be used at dp_bridge_init() at dp_drm.c later.

Therefore it need to be restored to NULL at failed case.



>
> Could you please post the backtrace that you have observed?

I do not have serial console port to collect logs.

If you still need it, i will collect it tomorrow.

>
>> @@ -1210,7 +1210,9 @@ static int dp_display_probe_tail(struct device *dev)
>>           dp->next_bridge = devm_drm_of_get_bridge(&dp->pdev->dev,
>> dp->pdev->dev.of_node, 1, 0);
>>           if (IS_ERR(dp->next_bridge)) {
>>                   ret = PTR_ERR(dp->next_bridge);
>> -               if (dp->is_edp || ret != -ENODEV)
>> +               dp->next_bridge = NULL;
>> +
>> +               if (!dp->is_edp && ret != -ENODEV)
>>                           return ret;
>>           }
>>>>> On 12/29/2023 2:56 PM, Dmitry Baryshkov wrote:
>>>>>> Remove two levels of indirection and fetch next bridge directly in
>>>>>> dp_display_probe_tail().
>>>>>>
>>>>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>>>>>> ---
>>>>>>     drivers/gpu/drm/msm/dp/dp_display.c | 42
>>>>>> +++++++++--------------------
>>>>>>     drivers/gpu/drm/msm/dp/dp_parser.c  | 14 ----------
>>>>>>     drivers/gpu/drm/msm/dp/dp_parser.h  | 14 ----------
>>>>>>     3 files changed, 13 insertions(+), 57 deletions(-)