> On Tue, Jan 31 2017 at 08:59:12 AM, Bharat Kumar Gogada > <[email protected]> wrote: > > - Adding mutex lock for protecting legacy mask register > > - Few wifi end points which only support legacy interrupts, performs > > hardware reset functionalities after disabling interrupts by invoking > > disable_irq and then re-enable using enable_irq, they enable hardware > > interrupts first and then virtual irq line later. > > - The legacy irq line goes low only after DEASSERT_INTx is received.As > > the legacy irq line is high immediately after hardware interrupts are > > enabled but virq of EP is still in disabled state and EP handler is > > never executed resulting no DEASSERT_INTx.If dummy irq chip is used, > > interrutps are not masked and system is hanging with CPU stall. > > - Adding irq chip functions instead of dummy irq chip for legacy > > interrupts. > > - Legacy interrupts are level sensitive, so using handle_level_irq is > > more appropriate as it is masks interrupts until End point handles > > interrupts and unmasks interrutps after End point handler is executed. > > - Legacy interrupts are level triggered, virtual irq line of End Point > > shows as edge in /proc/interrupts. > > - Setting irq flags of virtual irq line of EP to level triggered at > > the time of mapping. > > > > Signed-off-by: Bharat Kumar Gogada <[email protected]> > > --- > > drivers/pci/host/pcie-xilinx-nwl.c | 43 > +++++++++++++++++++++++++++++++++++- > > 1 files changed, 42 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/pci/host/pcie-xilinx-nwl.c > > b/drivers/pci/host/pcie-xilinx-nwl.c > > index 43eaa4a..76dd094 100644 > > --- a/drivers/pci/host/pcie-xilinx-nwl.c > > +++ b/drivers/pci/host/pcie-xilinx-nwl.c > > @@ -184,6 +184,7 @@ struct nwl_pcie { > > u8 root_busno; > > struct nwl_msi msi; > > struct irq_domain *legacy_irq_domain; > > + struct mutex leg_mask_lock; > > }; > > > > static inline u32 nwl_bridge_readl(struct nwl_pcie *pcie, u32 off) @@ > > -395,11 +396,50 @@ static void nwl_pcie_msi_handler_low(struct irq_desc > *desc) > > chained_irq_exit(chip, desc); > > } > > > > +static void nwl_mask_leg_irq(struct irq_data *data) { > > + struct irq_desc *desc = irq_to_desc(data->irq); > > + struct nwl_pcie *pcie; > > + u32 mask; > > + u32 val; > > + > > + pcie = irq_desc_get_chip_data(desc); > > + mask = 1 << (data->hwirq - 1); > > + mutex_lock(&pcie->leg_mask_lock); > > + val = nwl_bridge_readl(pcie, MSGF_LEG_MASK); > > + nwl_bridge_writel(pcie, (val & (~mask)), MSGF_LEG_MASK); > > + mutex_unlock(&pcie->leg_mask_lock); > > Have you looked at which context this is called in? In a number of cases, the > mask/unmask methods are called whilst you're in an interrupt context. If you > sleep there (which is what happens with a contended mutex), you die horribly. > > Given these constraints, you should use raw_spin_lock_irqsave and co, since > this > can be called from both interrupt and non-interrupt contexts. > I have seen very few wifi drivers calling these in MAC flow, raw_spin_lock_irqsave looks more safe, will do it.
Thanks & Regards, Bharat
