[PATCH v13 04/53] xhci: Add helper to set an interrupters interrupt moderation interval

Wesley Cheng
2024-02-03T02:37:45Z

From: Mathias Nyman <mathias.nyman@linux.intel.com>

Add a helper to set the interrupt moderation interval for an interrupter.
Each interrupter can have its own moderation value.

Hardware has a 16bit register for the moderation value, each step is 250ns.

Helper function imod_interval argument is in nanoseconds.

Values from 0 to 16383750 (250 x 0xffff) are accepted.
0 means no interrupt throttling.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
---
drivers/usb/host/xhci.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 0886829d53e5..b405b8236134 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -346,6 +346,23 @@ static int xhci_disable_interrupter(struct xhci_interrupter *ir)
return 0;
}

+/* interrupt moderation interval imod_interval in nanoseconds */
+static int xhci_set_interrupter_moderation(struct xhci_interrupter *ir,
+ u32 imod_interval)
+{
+ u32 imod;
+
+ if (!ir || !ir->ir_set || imod_interval > U16_MAX * 250)
+ return -EINVAL;
+
+ imod = readl(&ir->ir_set->irq_control);
+ imod &= ~ER_IRQ_INTERVAL_MASK;
+ imod |= (imod_interval / 250) & ER_IRQ_INTERVAL_MASK;
+ writel(imod, &ir->ir_set->irq_control);
+
+ return 0;
+}
+
static void compliance_mode_recovery(struct timer_list *t)
{
struct xhci_hcd *xhci;
@@ -528,7 +545,6 @@ static int xhci_run_finished(struct xhci_hcd *xhci)
*/
int xhci_run(struct usb_hcd *hcd)
{
- u32 temp;
u64 temp_64;
int ret;
struct xhci_hcd *xhci = hcd_to_xhci(hcd);
@@ -551,12 +567,7 @@ int xhci_run(struct usb_hcd *hcd)
xhci_dbg_trace(xhci, trace_xhci_dbg_init,
"ERST deq = 64'h%0lx", (long unsigned int) temp_64);

- xhci_dbg_trace(xhci, trace_xhci_dbg_init,
- "// Set the interrupt modulation register");
- temp = readl(&ir->ir_set->irq_control);
- temp &= ~ER_IRQ_INTERVAL_MASK;
- temp |= (xhci->imod_interval / 250) & ER_IRQ_INTERVAL_MASK;
- writel(temp, &ir->ir_set->irq_control);
+ xhci_set_interrupter_moderation(ir, xhci->imod_interval);

if (xhci->quirks & XHCI_NEC_HOST) {
struct xhci_command *command;