From: Janus Cheng <[email protected]>

* Symptom: if update_fw and update_cfg, kernel panic occurs.
* Reproducibility: 10%
* Root Cause:
  - If update_fw, the T6 will send a CFG_ERR message periodically.
  - After that, update_cfg process begin, the mxt_update_cfg_store() will
    invoke mxt_free_input_device() and nullify data->input_dev.
  - The CFG_ERR message will trigger mxt_interrupt(), and mxt_input_sync()
    will be invoked by mxt_process_messages_t44(). And mxt_input_sync()
    references a NULL data->input_dev and kernel panic occurs.

TrackerRMS TKT-004235

Signed-off-by: Nick Dyer <[email protected]>
(cherry picked from ndyer/linux/for-upstream commit 
c909ada856861f305653b127db3ea0fa60264331)
[gdavis: Resolve forward port conflicts due to applying upstream
         commit 96a938aa214e ("Input: atmel_mxt_ts - remove platform
         data support").]
Signed-off-by: George G. Davis <[email protected]>
Signed-off-by: Jiada Wang <[email protected]>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c 
b/drivers/input/touchscreen/atmel_mxt_ts.c
index a4f8364ecca9..99e5c84d207a 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -837,9 +837,11 @@ static void mxt_input_button(struct mxt_data *data, u8 
*message)
 
 static void mxt_input_sync(struct mxt_data *data)
 {
-       input_mt_report_pointer_emulation(data->input_dev,
-                                         data->t19_num_keys);
-       input_sync(data->input_dev);
+       if (data->input_dev) {
+               input_mt_report_pointer_emulation(data->input_dev,
+                                                 data->t19_num_keys);
+               input_sync(data->input_dev);
+       }
 }
 
 static void mxt_proc_t9_message(struct mxt_data *data, u8 *message)
-- 
2.19.2

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