On Fri, Jan 03, 2025 at 11:49:57AM -0600, Bjorn Helgaas wrote: > On Thu, Jan 02, 2025 at 05:43:26PM -0800, Brian Norris wrote: > > On Mon, Dec 30, 2024 at 10:41:45PM +0530, Manivannan Sadhasivam wrote: > > > On Tue, Oct 15, 2024 at 02:12:16PM -0700, Brian Norris wrote: > > > > From: Brian Norris <briannorris@xxxxxxxxxx> > > > > > > > > Per Synopsis's documentation, the msi_ctrl_int signal is > > > > level-triggered, not edge-triggered. > > > > > > Could you please quote the spec reference? > > > > From the reference manual for msi_ctrl_int: > > > > "Asserted when an MSI interrupt is pending. De-asserted when there is > > no MSI interrupt pending. > > ... > > Active State: High (level)" > > > > The reference manual also points at the databook for more info. One > > relevant excerpt from the databook: > > > > "When any status bit remains set, then msi_ctrl_int remains asserted. > > The interrupt status register provides a status bit for up to 32 > > interrupt vectors per Endpoint. When the decoded interrupt vector is > > enabled but is masked, then the controller sets the corresponding bit > > in interrupt status register but the it does not assert the top-level > > controller output msi_ctrl_int. > > "the it" might be a transcription error? > > > That's essentially a prose description of level-triggering, plus > > 32-vector multiplexing and masking. > > > > Did you want a v2 with this included, or did you just want it noted > > here? > > I think a v2 with citations (spec name, revision, section number) > would be helpful. Including these quotes as well would be fine with > me. Oh, and it would be awesome if we can motivate this patch by mentioning an actual problem it can avoid. It sounds like there really *is* a problem at least in some topologies, so I think we should describe that problem before explaining why we haven't seen it yet. > > (Side note: I think it doesn't really matter that much whether we use > > the 'level' or 'edge' variant handlers here, at least if the parent > > interrupt is configured correctly as level-triggered. We're not actually > > in danger of a level-triggered interrupt flood or similar issue.) > > > > Brian
