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

From: Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org>
To: Yunzhi Li <lyz-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
Cc: huangtao-TNX95d0MmH7DzftRWevZcw@public.gmane.org,
	hl-TNX95d0MmH7DzftRWevZcw@public.gmane.org,
	John Youn <johnyoun-HKixBCOQz3hWk0Htik3J/w@public.gmane.org>,
	Greg Kroah-Hartman
	<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
	linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org,
	balbi-l0cyMroinI0@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	cf-TNX95d0MmH7DzftRWevZcw@public.gmane.org,
	jwerner-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org
Subject: Re: [PATCH v1] usb: dwc2: reset AHB hclk domain before init
Date: Wed, 12 Aug 2015 14:32:44 -0500	[thread overview]
Message-ID: <20150812193244.GA20972@saruman.tx.rr.com> (raw)
In-Reply-To: <55CB28A1.6090208-TNX95d0MmH7DzftRWevZcw@public.gmane.org>

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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-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
> >>
> >>---
> >>
> >>  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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