[PATCH 03/10] usb: host: xhci-tegra: Avoid a fixed duration sleep

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

Do not use a fixed duration sleep to wait for the DMA controller to
become ready. Instead, poll the L2IMEMOP_RESULT register for the VLD
flag to determine when the XUSB controller's DMA master is ready.

Based on work by JC Kuo <jckuo@nvidia.com>.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/usb/host/xhci-tegra.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
index 5cfd54862670..d15fd16168ae 100644
--- a/drivers/usb/host/xhci-tegra.c
+++ b/drivers/usb/host/xhci-tegra.c
@@ -101,6 +101,8 @@
 #define  L2IMEMOP_ACTION_SHIFT			24
 #define  L2IMEMOP_INVALIDATE_ALL		(0x40 << L2IMEMOP_ACTION_SHIFT)
 #define  L2IMEMOP_LOAD_LOCKED_RESULT		(0x11 << L2IMEMOP_ACTION_SHIFT)
+#define XUSB_CSB_MEMPOOL_L2IMEMOP_RESULT	0x101a18
+#define  L2IMEMOP_RESULT_VLD			BIT(31)
 #define XUSB_CSB_MP_APMAP			0x10181c
 #define  APMAP_BOOTPATH				BIT(31)
 
@@ -893,7 +895,22 @@ static int tegra_xusb_load_firmware(struct tegra_xusb *tegra)
 
 	csb_writel(tegra, 0, XUSB_FALC_DMACTL);
 
-	msleep(50);
+	/* wait for RESULT_VLD to get set */
+	timeout = jiffies + msecs_to_jiffies(10);
+
+	do {
+		value = csb_readl(tegra, XUSB_CSB_MEMPOOL_L2IMEMOP_RESULT);
+		if (value & L2IMEMOP_RESULT_VLD)
+			break;
+
+		usleep_range(50, 100);
+	} while (time_is_after_jiffies(timeout));
+
+	value = csb_readl(tegra, XUSB_CSB_MEMPOOL_L2IMEMOP_RESULT);
+	if ((value & L2IMEMOP_RESULT_VLD) == 0) {
+		dev_err(dev, "DMA controller not ready %#010x\n", value);
+		return -EBUSY;
+	}
 
 	csb_writel(tegra, le32_to_cpu(header->boot_codetag),
 		   XUSB_FALC_BOOTVEC);
-- 
2.23.0