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

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Date:	Wed, 12 Aug 2015 14:32:44 -0500
From:	Felipe Balbi <balbi@...com>
To:	Yunzhi Li <lyz@...k-chips.com>
CC:	<balbi@...com>, <jwerner@...omium.org>, <dianders@...omium.org>,
	<huangtao@...k-chips.com>, <cf@...k-chips.com>,
	<hl@...k-chips.com>, <linux-rockchip@...ts.infradead.org>,
	John Youn <johnyoun@...opsys.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] usb: dwc2: reset AHB hclk domain before init

On Wed, Aug 12, 2015 at 07:06:09PM +0800, Yunzhi Li wrote:
> Hi ,
> 在 2015/8/11 22:12, Felipe Balbi 写道:
> >Hi,
> >
> >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@...k-chips.com>
> >>
> >>---
> >>
> >>  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 ?

even on platform only, how do you know all users provide a ahb_reset
reset controller ?

-- 
balbi

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