[PATCH 3/3] usb: xhci: allocate internal DCBAA mirror dynamically

[Niklas Neronin <niklas.neronin@linux.intel.com>]

Allocate the internal virtual device array dynamically based on the
maximum number of slots reported by the host controller. Previously,
the array was always allocated to the absolute maximum of 255 entries.

Repurpose the 'MAX_HC_SLOTS' macro to limit the number of enabled slots.
This mirrors how the maximum number of ports and interrupters are handled.

The allocation now uses kcalloc_node(), which zeroes the memory
automatically, making the explicit memset() call unnecessary.

Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
---
 drivers/usb/host/xhci-mem.c | 14 ++++++++++++--
 drivers/usb/host/xhci.c     |  4 +---
 drivers/usb/host/xhci.h     |  9 ++++++---
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index ac915dacd886..1effc9f08678 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1953,8 +1953,11 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "Freed command ring");
 	xhci_cleanup_command_queue(xhci);
 
-	for (i = xhci->max_slots; i > 0; i--)
-		xhci_free_virt_devices_depth_first(xhci, i);
+	if (xhci->devs) {
+		for (i = xhci->max_slots; i > 0; i--)
+			xhci_free_virt_devices_depth_first(xhci, i);
+		kfree(xhci->devs);
+	}
 
 	dma_pool_destroy(xhci->segment_pool);
 	xhci->segment_pool = NULL;
@@ -2011,6 +2014,7 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 	xhci->rh_bw = NULL;
 	xhci->port_caps = NULL;
 	xhci->interrupters = NULL;
+	xhci->devs = NULL;
 
 	xhci->usb2_rhub.bus_state.bus_suspended = 0;
 	xhci->usb3_rhub.bus_state.bus_suspended = 0;
@@ -2417,6 +2421,12 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "Starting %s", __func__);
 
+	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "Allocating internal virtual device array");
+	xhci->devs = kcalloc_node(xhci->max_slots + 1, sizeof(*xhci->devs), flags,
+				  dev_to_node(dev));
+	if (!xhci->devs)
+		goto fail;
+
 	xhci->dcbaa.ctx_array =
 		dma_alloc_coherent(dev, array_size(sizeof(*dcbaa->ctx_array), xhci->max_slots + 1),
 				   &dcbaa->dma, flags);
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 9a471bd72265..151a759806f8 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -5460,7 +5460,7 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
 	if (xhci->hci_version > 0x100)
 		xhci->hcc_params2 = readl(&xhci->cap_regs->hcc_params2);
 
-	xhci->max_slots = HCS_MAX_SLOTS(hcs_params1);
+	xhci->max_slots = min(HCS_MAX_SLOTS(hcs_params1), MAX_HC_SLOTS);
 	xhci->max_ports = min(HCS_MAX_PORTS(hcs_params1), MAX_HC_PORTS);
 	/* xhci-plat or xhci-pci might have set max_interrupters already */
 	if (!xhci->max_interrupters)
@@ -5533,8 +5533,6 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
 	init_completion(&xhci->cmd_ring_stop_completion);
 	xhci_hcd_page_size(xhci);
 
-	memset(xhci->devs, 0, MAX_HC_SLOTS * sizeof(*xhci->devs));
-
 	/* Allocate xHCI data structures */
 	retval = xhci_mem_init(xhci, GFP_KERNEL);
 	if (retval)
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index b467b875eeba..f977c8e6a90a 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -33,8 +33,11 @@
 /* xHCI PCI Configuration Registers */
 #define XHCI_SBRN_OFFSET	(0x60)
 
-/* Max number of USB devices for any host controller - limit in section 6.1 */
-#define MAX_HC_SLOTS		256
+/*
+ * Max number of Devices Slots. xHCI specification section 5.3.3
+ * Valid values are in the range of 1 to 255.
+ */
+#define MAX_HC_SLOTS		255
 /*
  * Max Number of Ports. xHCI specification section 5.3.3
  * Valid values are in the range of 1 to 255.
@@ -1552,7 +1555,7 @@ struct xhci_hcd {
 	/* these are not thread safe so use mutex */
 	struct mutex mutex;
 	/* Internal mirror of the HW's dcbaa */
-	struct xhci_virt_device	*devs[MAX_HC_SLOTS];
+	struct xhci_virt_device	**devs;
 	/* For keeping track of bandwidth domains per roothub. */
 	struct xhci_root_port_bw_info	*rh_bw;
 
-- 
2.50.1