drm/panfrost: Synchronize and disable interrupts before powering off

To make sure that we don't unintentionally perform any unclocked and/or
unpowered R/W operation on GPU registers, before turning off clocks and
regulators we must make sure that no GPU, JOB or MMU ISR execution is
pending: doing that requires to add a mechanism to synchronize the
interrupts on suspend.

Add functions panfrost_{gpu,job,mmu}_suspend_irq() which will perform
interrupts masking and ISR execution synchronization, and then call
those in the panfrost_device_runtime_suspend() handler in the exact
sequence of job (may require mmu!) -> mmu -> gpu.

As a side note, JOB and MMU suspend_irq functions needed some special
treatment: as their interrupt handlers will unmask interrupts, it was
necessary to add an `is_suspended` bitmap which is used to address the
possible corner case of unintentional IRQ unmasking because of ISR
execution after a call to synchronize_irq().

At resume, clear each is_suspended bit in the reset path of JOB/MMU
to allow unmasking the interrupts.

Signed-off-by: AngeloGioacchino Del Regno <[email protected]>
Reviewed-by: Boris Brezillon <[email protected]>
Tested-by: Marek Szyprowski <[email protected]>
Reviewed-by: Steven Price <[email protected]>
Signed-off-by: Boris Brezillon <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

0 files changed, 0 insertions, 0 deletions