Re: [PATCH v1] usb: dwc2: reset AHB hclk domain before init

From: Yunzhi Li
Date: Wed Aug 12 2015 - 07:06:23 EST

Hi ,
å 2015/8/11 22:12, Felipe Balbi åé:

On Tue, Aug 11, 2015 at 10:27:42AM +0800, Yunzhi Li wrote:
We initiate dwc2 usb controller in BIOS, when kernel driver
start-up we should reset AHB hclk domain to reset all AHB
interface registers to default. Without this the FIFO value
setting might be incorrect because calculating FIFO size need the
power-on value of GRXFSIZ/GNPTXFSIZ/HPTXFSIZ registers.

This patch could avoid warnning massage like in rk3288 platform:
[ 2.074764] dwc2 ff580000.usb: 256 invalid for
host_perio_tx_fifo_size. Check HW configuration.

Signed-off-by: Yunzhi Li <lyz@xxxxxxxxxxxxxx>


drivers/usb/dwc2/platform.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index 9093530..3da21ab 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -42,6 +42,7 @@
#include <linux/of_device.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
+#include <linux/reset.h>
#include <linux/usb/of.h>
@@ -165,6 +166,7 @@ static int dwc2_driver_probe(struct platform_device *dev)
struct resource *res;
struct phy *phy;
struct usb_phy *uphy;
+ struct reset_control *rst;
int retval;
int irq;
@@ -189,6 +191,16 @@ static int dwc2_driver_probe(struct platform_device *dev)
hsotg->dev = &dev->dev;
+ /* AHB hclk domain reset, set all AHB interface registers to default */
+ rst = devm_reset_control_get_optional(&dev->dev, "ahb_reset");
why isn't this done in core so PCI systems can also make use of it ?

I have no ides about how to reset a PCI interface dwc2 controller, John could you please give some infomation about it ?
Is it also needed for PCI interface dwc2 IP ?

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