diff options
| author | Niklas Neronin <niklas.neronin@linux.intel.com> | 2025-05-15 16:56:13 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-21 12:35:33 +0200 |
| commit | f5bce30ad25e74899c54dda01c80ca6e2e7dc01b (patch) | |
| tree | 8b94ecdc87fcc0b2196c155b24d00b0e43087ea9 | |
| parent | 9f7f74735ac295c9c32ac9152c362414e18d35cc (diff) | |
usb: xhci: guarantee that IMAN register is flushed
Add read call to guarantee that the write to the IMAN register has
been flushed.
xHCI specification 1.2, section 5.5.2.1, Note:
"Most systems have write buffers that minimize overhead, but this may
require a read operation to guarantee that the write has been flushed
from the posted buffer."
Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20250515135621.335595-17-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/host/xhci-ring.c | 3 | ||||
| -rw-r--r-- | drivers/usb/host/xhci.c | 3 |
2 files changed, 6 insertions, 0 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index d2002ecd27b0..4a4410f7978f 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -3087,6 +3087,9 @@ static void xhci_clear_interrupt_pending(struct xhci_interrupter *ir) irq_pending = readl(&ir->ir_set->irq_pending); irq_pending |= IMAN_IP; writel(irq_pending, &ir->ir_set->irq_pending); + + /* Read operation to guarantee the write has been flushed from posted buffers */ + readl(&ir->ir_set->irq_pending); } } diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 472589679af3..8cdb1a01a3ed 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -335,6 +335,8 @@ int xhci_enable_interrupter(struct xhci_interrupter *ir) iman |= IMAN_IE; writel(iman, &ir->ir_set->irq_pending); + /* Read operation to guarantee the write has been flushed from posted buffers */ + readl(&ir->ir_set->irq_pending); return 0; } @@ -350,6 +352,7 @@ int xhci_disable_interrupter(struct xhci_interrupter *ir) iman &= ~IMAN_IE; writel(iman, &ir->ir_set->irq_pending); + readl(&ir->ir_set->irq_pending); return 0; } |