On Mon, 2016-10-10 at 12:55 +0200, Matthias Brugger wrote:

On 09/21/2016 07:54 AM, Chunfeng Yun wrote:

quoted

Make IPPC register optional to support host side of dual-role mode,
due to it is moved into common glue layer for simplification.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
 drivers/usb/host/xhci-mtk.c |   36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/host/xhci-mtk.c b/drivers/usb/host/xhci-mtk.c
index 79959f1..4bf99b9 100644
--- a/drivers/usb/host/xhci-mtk.c
+++ b/drivers/usb/host/xhci-mtk.c

@@ -94,6 +94,9 @@ static int xhci_mtk_host_enable(struct xhci_hcd_mtk *mtk)
 	int ret;
 	int i;

+	if (ippc == NULL)
+		return 0;
+
 	/* power on host ip */
 	value = readl(&ippc->ip_pw_ctr1);
 	value &= ~CTRL1_IP_HOST_PDN;

@@ -139,6 +142,9 @@ static int xhci_mtk_host_disable(struct xhci_hcd_mtk *mtk)
 	int ret;
 	int i;

+	if (ippc == NULL)
+		return 0;
+
 	/* power down all u3 ports */
 	for (i = 0; i < mtk->num_u3_ports; i++) {
 		value = readl(&ippc->u3_ctrl_p[i]);

@@ -173,6 +179,9 @@ static int xhci_mtk_ssusb_config(struct xhci_hcd_mtk *mtk)
 	struct mu3c_ippc_regs __iomem *ippc = mtk->ippc_regs;
 	u32 value;

+	if (ippc == NULL)
+		return 0;
+

I would prefer to add a flag/bool in xhci_hcd_mtk to signal the absence 
of the ippc. Or at least use a macro which checks the presence before 
calling any of this three functions.

Ok. I will modify it later.

thanks.

Regards,
Matthias