usb: xhci: set requested IMODI to the closest supported value

The function configures the Interrupt Moderation Interval (IMODI) via bits
15:0 in the Interrupt Moderation Register. The IMODI value is specified in
increments of 250 nanoseconds. For instance, an IMODI register value of 16
corresponds to 4000 nanoseconds, resulting in an interrupt every ~1ms.

Currently, the function fails when a requested IMODI value is too large,
only logging a warning message for secondary interrupters. Prevent this by
automatically adjusting the IMODI value to the nearest supported value.

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/20250515135621.335595-15-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 08513e5..dcfe777 100644 (file)
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -2393,10 +2393,7 @@ xhci_create_secondary_interrupter(struct usb_hcd *hcd, unsigned int segs,
                return NULL;
        }
 
-       err = xhci_set_interrupter_moderation(ir, imod_interval);
-       if (err)
-               xhci_warn(xhci, "Failed to set interrupter %d moderation to %uns\n",
-                         i, imod_interval);
+       xhci_set_interrupter_moderation(ir, imod_interval);
 
        xhci_dbg(xhci, "Add secondary interrupter %d, max interrupters %d\n",
                 ir->intr_num, xhci->max_interrupters);

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index c6b5174..c3a1a67 100644 (file)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -355,12 +355,15 @@ int xhci_set_interrupter_moderation(struct xhci_interrupter *ir,
 {
        u32 imod;
 
-       if (!ir || !ir->ir_set || imod_interval > U16_MAX * 250)
+       if (!ir || !ir->ir_set)
                return -EINVAL;
 
+       /* IMODI value in IMOD register is in 250ns increments */
+       imod_interval = umin(imod_interval / 250, ER_IRQ_INTERVAL_MASK);
+
        imod = readl(&ir->ir_set->irq_control);
        imod &= ~ER_IRQ_INTERVAL_MASK;
-       imod |= (imod_interval / 250) & ER_IRQ_INTERVAL_MASK;
+       imod |= imod_interval;
        writel(imod, &ir->ir_set->irq_control);
 
        return 0;