* [PATCH 1/2] usb: xhci: improve HCD page size validation and setting
2024-10-25 11:26 [PATCH 0/2] usb: xhci: improve HCD page size & IMODI Niklas Neronin
@ 2024-10-25 11:27 ` Niklas Neronin
2024-10-28 13:13 ` Mathias Nyman
2024-10-25 11:27 ` [PATCH 2/2] usb: xhci: improve xhci_set_interrupter_moderation() Niklas Neronin
1 sibling, 1 reply; 4+ messages in thread
From: Niklas Neronin @ 2024-10-25 11:27 UTC (permalink / raw)
To: mathias.nyman; +Cc: linux-usb, Niklas Neronin
xHC supports a page size of (2^(n+12)), where 'n' is the Page Size Bit.
The page size of 4096 bytes is common and always supported. Consequently,
the xHCI driver always sets the 'page_size' to 4096 (i.e., (1 << 12)).
At present, the xHCI driver reads the Page Size register but does not use
the value, except for printing a two useless debug traces. This introduces
unnecessary code into xhci_mem_init(), which is already quite large.
Although the page size is not currently modified, it may be in the future.
To balance both current and future needs, the page size setting code is
moved to a separate function. This rework ensures that the Page Size
register is not read for the minimum value (4096). However, if a different
value is provided, it will not be ignored, rather clamped between the
valid min and max page size.
Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
---
drivers/usb/host/xhci-mem.c | 40 ++++++++++++++++++++++---------------
drivers/usb/host/xhci.h | 9 ++++++---
2 files changed, 30 insertions(+), 19 deletions(-)
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index d2900197a49e..8a6b91862cae 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1959,7 +1959,6 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
xhci->interrupters = NULL;
xhci->page_size = 0;
- xhci->page_shift = 0;
xhci->usb2_rhub.bus_state.bus_suspended = 0;
xhci->usb3_rhub.bus_state.bus_suspended = 0;
}
@@ -2378,6 +2377,27 @@ xhci_create_secondary_interrupter(struct usb_hcd *hcd, unsigned int segs,
}
EXPORT_SYMBOL_GPL(xhci_create_secondary_interrupter);
+static void xhci_hcd_page_size(struct xhci_hcd *xhci)
+{
+ u32 page_size;
+
+ if (xhci->page_size <= HCD_PAGE_MIN) {
+ xhci->page_size = HCD_PAGE_MIN;
+ } else {
+ /* Max page size is 2^(n+12), where 'n' is the first 15:0 bit set */
+ page_size = readl(&xhci->op_regs->page_size) & HCD_PAGE_SIZE_MASK;
+ page_size = 1 << (ffs(page_size) + 12);
+
+ if (page_size < xhci->page_size)
+ xhci->page_size = page_size;
+ else
+ xhci->page_size = (1 << ffs(xhci->page_size));
+ }
+
+ xhci_dbg_trace(xhci, trace_xhci_dbg_init, "HCD page size set to %iK",
+ xhci->page_size / 1024);
+}
+
int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
{
struct xhci_interrupter *ir;
@@ -2385,7 +2405,7 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
dma_addr_t dma;
unsigned int val, val2;
u64 val_64;
- u32 page_size, temp;
+ u32 temp;
int i;
INIT_LIST_HEAD(&xhci->cmd_list);
@@ -2394,20 +2414,8 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
INIT_DELAYED_WORK(&xhci->cmd_timer, xhci_handle_command_timeout);
init_completion(&xhci->cmd_ring_stop_completion);
- page_size = readl(&xhci->op_regs->page_size);
- xhci_dbg_trace(xhci, trace_xhci_dbg_init,
- "Supported page size register = 0x%x", page_size);
- i = ffs(page_size);
- if (i < 16)
- xhci_dbg_trace(xhci, trace_xhci_dbg_init,
- "Supported page size of %iK", (1 << (i+12)) / 1024);
- else
- xhci_warn(xhci, "WARN: no supported page size\n");
- /* Use 4K pages, since that's common and the minimum the HC supports */
- xhci->page_shift = 12;
- xhci->page_size = 1 << xhci->page_shift;
- xhci_dbg_trace(xhci, trace_xhci_dbg_init,
- "HCD page size set to %iK", xhci->page_size / 1024);
+ /* If 'page_size' is not set, use 4K pages, since that's common and always supported */
+ xhci_hcd_page_size(xhci);
/*
* Program the Number of Device Slots Enabled field in the CONFIG
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index f0fb696d5619..f998df70f80f 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -211,6 +211,11 @@ struct xhci_op_regs {
#define CONFIG_CIE (1 << 9)
/* bits 10:31 - reserved and should be preserved */
+/* bits 15:0 - HCD page shift bit */
+#define HCD_PAGE_SIZE_MASK 0xffff
+/* HCD page size 4KB up to 128MB, Rev 1.2 Section 5.4.3. */
+#define HCD_PAGE_MIN (1 << 12)
+
/**
* struct xhci_intr_reg - Interrupt Register Set
* @irq_pending: IMAN - Interrupt Management Register. Used to enable
@@ -1502,10 +1507,8 @@ struct xhci_hcd {
u16 max_interrupters;
/* imod_interval in ns (I * 250ns) */
u32 imod_interval;
- /* 4KB min, 128MB max */
+ /* Always set to HCD_PAGE_MIN (4KB) */
int page_size;
- /* Valid values are 12 to 20, inclusive */
- int page_shift;
/* MSI-X/MSI vectors */
int nvecs;
/* optional clocks */
--
2.45.2
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 2/2] usb: xhci: improve xhci_set_interrupter_moderation()
2024-10-25 11:26 [PATCH 0/2] usb: xhci: improve HCD page size & IMODI Niklas Neronin
2024-10-25 11:27 ` [PATCH 1/2] usb: xhci: improve HCD page size validation and setting Niklas Neronin
@ 2024-10-25 11:27 ` Niklas Neronin
1 sibling, 0 replies; 4+ messages in thread
From: Niklas Neronin @ 2024-10-25 11:27 UTC (permalink / raw)
To: mathias.nyman; +Cc: linux-usb, Niklas Neronin
The function sets the interrupt moderation interval through the IMODI
16-bit register, where the interval is represented in increments of 250
nanoseconds. For example, an IMODI register value of 16 is multiplied by
250 to get 4000 nanoseconds, resulting in an interrupt every ~1ms.
Currently, the function has the potential to fail, but this failure is not
handled, and the xhci driver proceeds as usual. Fix the issue by removing
the possibility of failure. Instead, the IMODI is set to the closest valid
value.
Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
---
drivers/usb/host/xhci-mem.c | 5 +----
drivers/usb/host/xhci.c | 25 +++++++++++++------------
drivers/usb/host/xhci.h | 4 ++--
3 files changed, 16 insertions(+), 18 deletions(-)
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 8a6b91862cae..7355ca85e1b3 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -2365,10 +2365,7 @@ 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(xhci, ir, imod_interval);
xhci_dbg(xhci, "Add secondary interrupter %d, max interrupters %d\n",
i, xhci->max_interrupters);
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 899c0effb5d3..9bf5d2e09c60 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -346,21 +346,22 @@ static int xhci_disable_interrupter(struct xhci_interrupter *ir)
return 0;
}
-/* interrupt moderation interval imod_interval in nanoseconds */
-int xhci_set_interrupter_moderation(struct xhci_interrupter *ir,
- u32 imod_interval)
+/* Interrupt moderation interval in 250 nanoseconds increments, 0 means no interrupt throttling. */
+void xhci_set_interrupter_moderation(struct xhci_hcd *xhci, struct xhci_interrupter *ir,
+ u32 imod_interval)
{
- u32 imod;
+ u32 irq_control;
- if (!ir || !ir->ir_set || imod_interval > U16_MAX * 250)
- return -EINVAL;
+ imod_interval /= 250;
+ imod_interval = min(imod_interval, U16_MAX);
- 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);
+ irq_control = readl(&ir->ir_set->irq_control);
+ irq_control &= ~ER_IRQ_INTERVAL_MASK;
+ irq_control |= imod_interval & ER_IRQ_INTERVAL_MASK;
+ writel(irq_control, &ir->ir_set->irq_control);
- return 0;
+ xhci_dbg(xhci, "Interrupt moderation interval set to %uns for interrupt %u\n",
+ imod_interval * 250, ir->intr_num);
}
static void compliance_mode_recovery(struct timer_list *t)
@@ -567,7 +568,7 @@ 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_set_interrupter_moderation(ir, xhci->imod_interval);
+ xhci_set_interrupter_moderation(xhci, ir, xhci->imod_interval);
if (xhci->quirks & XHCI_NEC_HOST) {
struct xhci_command *command;
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index f998df70f80f..8a47cb059582 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1871,8 +1871,8 @@ int xhci_alloc_tt_info(struct xhci_hcd *xhci,
struct xhci_virt_device *virt_dev,
struct usb_device *hdev,
struct usb_tt *tt, gfp_t mem_flags);
-int xhci_set_interrupter_moderation(struct xhci_interrupter *ir,
- u32 imod_interval);
+void xhci_set_interrupter_moderation(struct xhci_hcd *xhci, struct xhci_interrupter *ir,
+ u32 imod_interval);
/* xHCI ring, segment, TRB, and TD functions */
dma_addr_t xhci_trb_virt_to_dma(struct xhci_segment *seg, union xhci_trb *trb);
--
2.45.2
^ permalink raw reply related [flat|nested] 4+ messages in thread