From 468c49f44759720a312e52d44a71c3949ed63d7c Mon Sep 17 00:00:00 2001 From: Mario Limonciello Date: Fri, 10 Mar 2023 11:20:50 -0600 Subject: thunderbolt: Disable interrupt auto clear for rings When interrupt auto clear is programmed, any read to the interrupt status register will clear all interrupts. If two interrupts have come in before one can be serviced then this will cause lost interrupts. On AMD USB4 routers this has manifested in odd problems particularly with long strings of control tranfers such as reading the DROM via bit banging. Instead of clearing interrupts automatically, clear the bit corresponding to the given ring's interrupt in the ISR. Fixes: 7a1808f82a37 ("thunderbolt: Handle ring interrupt by reading interrupt status register") Cc: Sanju Mehta Cc: stable@vger.kernel.org Tested-by: Anson Tsao Signed-off-by: Mario Limonciello Signed-off-by: Mika Westerberg --- drivers/thunderbolt/nhi.c | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-) (limited to 'drivers/thunderbolt/nhi.c') diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c index fdc0c3ba2ef0..318d20bd5b69 100644 --- a/drivers/thunderbolt/nhi.c +++ b/drivers/thunderbolt/nhi.c @@ -71,24 +71,31 @@ static void ring_interrupt_active(struct tb_ring *ring, bool active) u32 step, shift, ivr, misc; void __iomem *ivr_base; int index; + int bit; if (ring->is_tx) index = ring->hop; else index = ring->hop + ring->nhi->hop_count; - if (ring->nhi->quirks & QUIRK_AUTO_CLEAR_INT) { - /* - * Ask the hardware to clear interrupt status - * bits automatically since we already know - * which interrupt was triggered. - */ - misc = ioread32(ring->nhi->iobase + REG_DMA_MISC); - if (!(misc & REG_DMA_MISC_INT_AUTO_CLEAR)) { - misc |= REG_DMA_MISC_INT_AUTO_CLEAR; - iowrite32(misc, ring->nhi->iobase + REG_DMA_MISC); - } - } + /* + * Intel routers support a bit that isn't part of + * the USB4 spec to ask the hardware to clear + * interrupt status bits automatically since + * we already know which interrupt was triggered. + * + * Other routers explicitly disable auto-clear + * to prevent conditions that may occur where two + * MSIX interrupts are simultaneously active and + * reading the register clears both of them. + */ + misc = ioread32(ring->nhi->iobase + REG_DMA_MISC); + if (ring->nhi->quirks & QUIRK_AUTO_CLEAR_INT) + bit = REG_DMA_MISC_INT_AUTO_CLEAR; + else + bit = REG_DMA_MISC_DISABLE_AUTO_CLEAR; + if (!(misc & bit)) + iowrite32(misc | bit, ring->nhi->iobase + REG_DMA_MISC); ivr_base = ring->nhi->iobase + REG_INT_VEC_ALLOC_BASE; step = index / REG_INT_VEC_ALLOC_REGS * REG_INT_VEC_ALLOC_BITS; @@ -393,14 +400,17 @@ EXPORT_SYMBOL_GPL(tb_ring_poll_complete); static void ring_clear_msix(const struct tb_ring *ring) { + int bit; + if (ring->nhi->quirks & QUIRK_AUTO_CLEAR_INT) return; + bit = ring_interrupt_index(ring) & 31; if (ring->is_tx) - ioread32(ring->nhi->iobase + REG_RING_NOTIFY_BASE); + iowrite32(BIT(bit), ring->nhi->iobase + REG_RING_INT_CLEAR); else - ioread32(ring->nhi->iobase + REG_RING_NOTIFY_BASE + - 4 * (ring->nhi->hop_count / 32)); + iowrite32(BIT(bit), ring->nhi->iobase + REG_RING_INT_CLEAR + + 4 * (ring->nhi->hop_count / 32)); } static irqreturn_t ring_msix(int irq, void *data) -- cgit v1.2.3