Revert "usb: xhci: set page size to the xHCI-supported size"

This reverts commit 1c17190880 which is
commit 68c1f1671650b49bbd26e6a65ddcf33f2565efa3 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I86a180900b707071e5d8fca2cec1ac304ad075a7
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/usb/host/xhci-mem.c

@@ -1950,6 +1950,7 @@ no_bw:
 	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;
 }
@@ -2372,22 +2373,6 @@ 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;
-
-	page_size = readl(&xhci->op_regs->page_size) & XHCI_PAGE_SIZE_MASK;
-	if (!is_power_of_2(page_size)) {
-		xhci_warn(xhci, "Invalid page size register = 0x%x\n", page_size);
-		/* Fallback to 4K page size, since that's common */
-		page_size = 1;
-	}
-
-	xhci->page_size = page_size << 12;
-	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "HCD page size set to %iK",
-		       xhci->page_size >> 10);
-}
-
 int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 {
 	struct xhci_interrupter *ir;
@@ -2395,7 +2380,7 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 	dma_addr_t	dma;
 	unsigned int	val, val2;
 	u64		val_64;
-	u32		temp;
+	u32		page_size, temp;
 	int		i;
 
 	INIT_LIST_HEAD(&xhci->cmd_list);
@@ -2404,7 +2389,20 @@ 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);
 
-	xhci_hcd_page_size(xhci);
+	page_size = readl(&xhci->op_regs->page_size);
+	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
+			"Supported page size register = 0x%x", page_size);
+	val = ffs(page_size) - 1;
+	if (val < 16)
+		xhci_dbg_trace(xhci, trace_xhci_dbg_init,
+			"Supported page size of %iK", (1 << (val + 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);
 
 	/*
 	 * Program the Number of Device Slots Enabled field in the CONFIG

drivers/usb/host/xhci.h

@@ -212,9 +212,6 @@ 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 XHCI_PAGE_SIZE_MASK     0xffff
-
 /**
  * struct xhci_intr_reg - Interrupt Register Set
  * @irq_pending:	IMAN - Interrupt Management Register.  Used to enable
@@ -1523,7 +1520,10 @@ struct xhci_hcd {
 	u16		max_interrupters;
 	/* imod_interval in ns (I * 250ns) */
 	u32		imod_interval;
-	u32		page_size;
+	/* 4KB min, 128MB max */
+	int		page_size;
+	/* Valid values are 12 to 20, inclusive */
+	int		page_shift;
 	/* MSI-X/MSI vectors */
 	int		nvecs;
 	/* optional clocks */