Re: drm: bridge: analogix/dp: Fix the possible dead lock in bridge disable time

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Hi Dan,

On 04/07/2016 03:41 AM, Dan Carpenter wrote:
Hello Yakir Yang,

The patch 7b4b7a8db439: "drm: bridge: analogix/dp: Fix the possible
dead lock in bridge disable time" from Feb 15, 2016, leads to the
following static checker warning:

	drivers/gpu/drm/bridge/analogix/analogix_dp_core.c:875 analogix_dp_irq_thread()
	warn: bitwise AND condition is false here

drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
    869  static irqreturn_t analogix_dp_irq_thread(int irq, void *arg)
    870  {
    871          struct analogix_dp_device *dp = arg;
    872          enum dp_irq_type irq_type;
    873
    874          irq_type = analogix_dp_get_irq_type(dp);
    875          if (irq_type & DP_IRQ_TYPE_HP_CABLE_IN ||
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This is never true.  Maybe test_bit() for these?
Ah, yep, it's an error here. The enum value of DP_IRQ_TYPE_HP_CABLE_IN
is zero, so even if analogix_dp_get_irq_type return the CABLE_IN event, driver
could not send the drm hpd event rightly.

Good catch, would need to assign the new enum value, like

 enum dp_irq_type {
-       DP_IRQ_TYPE_HP_CABLE_IN,
-       DP_IRQ_TYPE_HP_CABLE_OUT,
-       DP_IRQ_TYPE_HP_CHANGE,
-       DP_IRQ_TYPE_UNKNOWN,
+       DP_IRQ_TYPE_HP_CABLE_IN  = BIT(0),
+       DP_IRQ_TYPE_HP_CABLE_OUT = BIT(1),
+       DP_IRQ_TYPE_HP_CHANGE    = BIT(2),
+       DP_IRQ_TYPE_UNKNOWN      = BIT(3),
 };


Thanks for pointing out, would send patch to fix that soon.

- Yakir

    876              irq_type & DP_IRQ_TYPE_HP_CABLE_OUT) {
    877                  dev_dbg(dp->dev, "Detected cable status changed!\n");
    878                  if (dp->drm_dev)
    879                          drm_helper_hpd_irq_event(dp->drm_dev);
    880          }
    881
    882          if (irq_type != DP_IRQ_TYPE_UNKNOWN) {
    883                  analogix_dp_clear_hotplug_interrupts(dp);
    884                  analogix_dp_unmute_hpd_interrupt(dp);
    885          }
    886
    887          return IRQ_HANDLED;
    888  }

regards,
dan carpenter





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