On Wed, Mar 22, 2017 at 1:44 PM, William Breathitt Gray
[off-list ref] wrote:

On Tue, Mar 21, 2017 at 05:43:07PM -0500, Julia Cartwright wrote:

quoted

The 104-idi-48 gpio driver currently implements an irq_chip for handling
interrupts; due to how irq_chip handling is done, it's necessary for the
irq_chip methods to be invoked from hardirq context, even on a a
real-time kernel.  Because the spinlock_t type becomes a "sleeping"
spinlock w/ RT kernels, it is not suitable to be used with irq_chips.

A quick audit of the operations under the lock reveal that they do only
minimal, bounded work, and are therefore safe to do under a raw spinlock.

Signed-off-by: Julia Cartwright <redacted>

Hi Julia,

This driver also uses a second spinlock_t, called ack_lock, to prevent
reentrance into the idi_48_irq_handler function. Should ack_lock also be
implemented as a raw_spinlock_t?

Hm, can I apply this one patch or not?

Linus Walleij