On 28/03/2024 17:00, Sean Anderson wrote:
On 3/27/24 08:27, Tomi Valkeinen wrote:
Hi,
On 08/03/2024 23:00, Sean Anderson wrote:
xilinx_dpdma_chan_done_irq and xilinx_dpdma_chan_vsync_irq are always
called with IRQs disabled from xilinx_dpdma_irq_handler. Therefore we
don't need to save/restore the IRQ flags.
I think this is fine, but a few thoughts:
- Is spin_lock clearly faster than the irqsave variant, or is this a pointless optimization? It's safer to just use irqsave variant, instead of making sure the code is always called from the expected contexts.
It's not an optimization. Technically this will save a few instructions,
but...
- Is this style documented/recommended anywhere? Going through docs, I only found docs telling to use irqsave when mixing irq and non-irq contexts.
The purpose is mainly to make it clear that this is meant to be called
in IRQ context. With irqsave, there's an implication that this could be
called in non-IRQ context, which it never is.
Hmm, I see. Yes, I think that makes sense.
- Does this cause issues on PREEMPT_RT?
Why would it?
I was reading locktypes.rst, I started wondering what it means if
spinlocks are changed into sleeping locks. But thinking about it again,
it doesn't matter, as the irq will still be masked when in irq-context.
So:
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Tomi
