Re: [PATCH v1 41/63] Input: touchscreen: Atmel: Enable IRQ_DISABLE_UNLAZY flag for interrupt

From: Jiada Wang
Date: Thu Aug 22 2019 - 09:44:08 EST


Hi Dmitry

On 2019/08/17 2:26, Dmitry Torokhov wrote:
On Fri, Aug 16, 2019 at 05:35:36PM +0900, Jiada Wang wrote:
From: Bhuvanesh Surachari <bhuvanesh_surachari@xxxxxxxxxx>

The de-/serializer driver has defined only irq_mask "ds90ub927_irq_mask" and
irq_unmask "ds90ub927_irq_unmask" callback functions. And de-/serializer
driver doesn't implement the irq_disable and irq_enable callback functions.
Hence inorder to invoke irq_mask callback function when disable_irq_nosync is
called the IRQ_DISABLE_UNLAZY interrupt flag should be set. If not the
disable_irq_nosync will just increment the depth field in the irq
descriptor only once as shown below.

disable_irq_nosync
__disable_irq_nosync
__disable_irq (desc->depth++)
irq_disable
if irq_disable present -----------> if IRQ_DISABLE_UNLAZYflag set
| no |
yes | yes |
| |
desc->irq_data.chip->irq_disable desc->irq_data.chip->irq_unmask
(ds90ub927_irq_mask)
disable_irq
__disable_irq_nosync
__disable_irq
(desc->depth++)
But the enable_irq will try to decrement the depth field twice which generates
the backtrace stating "Unbalanced enable for irq 293". This is because there is
no IRQ_DISABLE_UNLAZY flag check while calling irq_unmask callback function
of the "ds90ub927_irq_unmask" de-/serializer via enable_irq.

enable_irq
__enable_irq (desc->depth--)
irq_enable
if irq_enable present -------------> desc->irq_data.chip->irq_unmask
| no (ds90ub927_irq_unmask)
yes | enable_irq
| __enable_irq (desc->depth--)
(desc->irq_data.chip->irq_enable)

I'd prefer if we instead did not use the disable_irq_nosync() in the
driver.

sorry for the mistake, during forward port,
I have already eliminated disable_irq_nosync(),
so this patch is no longer needed,
will drop it in v2 patch-set

Thanksï
Jiada

Thanks.