On Thu, 12 May 2022 18:55:38 +0100, "Lad, Prabhakar" <prabhakar.csengg@xxxxxxxxx> wrote: > > Hi Marc, > > On Thu, May 12, 2022 at 5:26 PM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > > > On Thu, 12 May 2022 14:50:05 +0100, > > "Lad, Prabhakar" <prabhakar.csengg@xxxxxxxxx> wrote: > > > > > > Hi Marc, > > > > > > On Thu, May 12, 2022 at 2:24 PM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > > > > > > > On Thu, 12 May 2022 13:48:53 +0100, > > > > "Lad, Prabhakar" <prabhakar.csengg@xxxxxxxxx> wrote: > > > > > > > > > > Hi Marc, > > > > > > > > > > Thank you for the review. > > > > > > > > > > On Thu, May 12, 2022 at 12:19 PM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > > > > > > > > > > > On Wed, 11 May 2022 19:32:08 +0100, > > > > > > Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx> wrote: > > > > > > > > > > > > > > Allow free() callback to be overridden from irq_domain_ops for > > > > > > > hierarchical chips. > > > > > > > > > > > > > > This allows drivers to free any resources which are allocated during > > > > > > > populate_parent_alloc_arg(). > > > > > > > > > > > > Do you mean more than the fwspec? I don't see this being used. > > > > > > > > > > > The free callback is used in patch 5/5 where free is overridden by > > > > > rzg2l_gpio_irq_domain_free. I just gave an example there as an > > > > > populate_parent_alloc_arg() In actual in the child_to_parent_hwirq > > > > > callback I am using a bitmap [0] to get a free tint slot, this bitmap > > > > > needs freeing up when the GPIO interrupt is released from the driver > > > > > that as when overridden free callback frees the allocated tint slot so > > > > > that its available for re-use. > > > > > > > > Right, so that's actually a different life-cycle, and the whole > > > > populate_parent_alloc_arg() is a red herring. What you want is to free > > > > resources that have been allocated via some other paths. It'd be good > > > Is there any other path which I have missed where I can free up resources? > > > > No, that's the only one. It is just that usually, the alloc() > > callback is where you are supposed to perform... allocations. > > > OK. > > > It'd be good if you could move your allocation there, as I would > > expect calls to child_to_parent_hwirq() to be idempotent. > > > For now I'll go with the current implementation, as currently a an > array is maintained which is tied with the tint slot and child (which > is obtained from child_to_parent_hwirq) > > > > > > > > if your commit message actually reflected this instead of using an > > > > example that doesn't actually exist. > > > > > > > My bad, I will update the commit message. > > > > > > > > > > > > > > There is also the question of why we need to have dynamic allocation > > > > > > for the fwspec itself. Why isn't that a simple stack allocation in the > > > > > > context of gpiochip_hierarchy_irq_domain_alloc()? > > > > > > > > > > > you mean gpio core itself should handle the fwspec > > > > > allocation/freeing? > > > > > > > > Yes. The only reason we resort to dynamic allocation is because > > > > ThunderX is using MSI-based GPIOs, and thus doesn't use a fwspec (no > > > > firmware is involved here). > > > > > > > I see.. > > > > > > > If we had a union of the two types, we could just have a stack > > > > variable, and pass that along, completely sidestepping the whole > > > > dynamic allocation/freeing business. > > > > > > > Right agreed. > > > > FWIW, I've just posted a PoC patch[1]. > > > I guess I'll have to rebase my changes on top of it now ;) Not yet. Let's see what people say about it. M. -- Without deviation from the norm, progress is not possible.
