linux-kernel - Re: [PATCH v4 6/6] usb: musb: Add support for MediaTek musb controller

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Date:   Tue, 22 Jan 2019 09:45:15 +0800
From:   Min Guo <min.guo@...iatek.com>
To:     Bin Liu <b-liu@...com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mark Rutland <mark.rutland@....com>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        Alan Stern <stern@...land.harvard.edu>,
        <chunfeng.yun@...iatek.com>, <linux-usb@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>, <tony@...mide.com>,
        <hdegoede@...hat.com>, Yonglong Wu <yonglong.wu@...iatek.com>
Subject: Re: [PATCH v4 6/6] usb: musb: Add support for MediaTek musb
 controller

Hi Bin,

On Mon, 2019-01-21 at 10:07 -0600, Bin Liu wrote:
> Hi Min,
> 
> On Mon, Jan 21, 2019 at 08:22:31PM +0800, min.guo@...iatek.com wrote:
> > From: Min Guo <min.guo@...iatek.com>
> > 
> > This adds support for MediaTek musb controller in
> > host, peripheral and otg mode.
> > There are some quirk of MediaTek musb controller, such as:
> >  -W1C interrupt status registers
> >  -Private data toggle registers
> >  -No dedicated DMA interrupt line
> > 
> > Signed-off-by: Min Guo <min.guo@...iatek.com>
> > Signed-off-by: Yonglong Wu <yonglong.wu@...iatek.com>
> > ---
> > changes in v4:
> > 1. no changes
> > 
> > changes in v3:
> > suggested by Bin:
> > 1. Remove 'u8/u16 data' parameter in clearb/w() hooks
> > 2. Replace musb_readb/w() with musb_clearb/w() to clear interrupts status
> > 
> > changes in v2:
> > suggested by Bin:
> > 1. Add summarize of MediaTek musb controller differences in the commit log
> > 2. Add "|| COMPILE_TEST" in Kconfig
> > 3. Move MediaTek's private toggle registers from musb_regs.h to mediatek.c
> > 4. Replace musb_readl() with musb_readw() to read 16bit toggle register
> > ---
> >  drivers/usb/musb/Kconfig    |   8 +-
> >  drivers/usb/musb/Makefile   |   1 +
> >  drivers/usb/musb/mediatek.c | 624 ++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 632 insertions(+), 1 deletion(-)
> >  create mode 100644 drivers/usb/musb/mediatek.c
> > 
> 
> [snip]
> 
> > +static irqreturn_t generic_interrupt(int irq, void *__hci)
> > +{
> > +	unsigned long flags;
> > +	irqreturn_t retval = IRQ_NONE;
> > +	struct musb *musb = __hci;
> > +
> > +	spin_lock_irqsave(&musb->lock, flags);
> > +	musb->int_usb = musb_readb(musb->mregs, MUSB_INTRUSB) &
> > +	    musb_readb(musb->mregs, MUSB_INTRUSBE);
> > +	musb->int_tx = musb_readw(musb->mregs, MUSB_INTRTX)
> > +	    & musb_readw(musb->mregs, MUSB_INTRTXE);
> > +	musb->int_rx = musb_readw(musb->mregs, MUSB_INTRRX)
> > +	    & musb_readw(musb->mregs, MUSB_INTRRXE);
> 
> Based on my comment in 5/6, the above 3 musb_readb/w() can be changed to
> 
> > +	/* MediaTek controller interrupt status is W1C */
> > +	musb_clearw(musb->mregs, MUSB_INTRRX);
> > +	musb_clearw(musb->mregs, MUSB_INTRTX);
> > +	musb_clearb(musb->mregs, MUSB_INTRUSB);
> 
> 	musb->int_usb = musb_clearb(musb->mregs, MUSB_INTRUSB)
> 	musb->int_tx = musb_clearw(musb->mregs, MUSB_INTRTX);
> 	musb->int_rx = musb_clearw(musb->mregs, MUSB_INTRRX);

Okay.

> > +
> > +	if (musb->int_usb || musb->int_tx || musb->int_rx)
> > +		retval = musb_interrupt(musb);
> > +
> > +	spin_unlock_irqrestore(&musb->lock, flags);
> > +
> > +	return retval;
> > +}
> > +
> 
> [snip]
> 
> > +
> > +static u8 mtk_musb_clearb(void __iomem *addr, unsigned int offset)
> > +{
> > +	u8 data;
> > +
> > +	/* W1C */
> > +	data = musb_readb(addr, offset);
> > +	musb_writeb(addr, offset, data);
> > +	return musb_readb(addr, offset);
> 
> 	return data;

Okay.

> > +}
> > +
> > +static u16 mtk_musb_clearw(void __iomem *addr, unsigned int offset)
> > +{
> > +	u16 data;
> > +
> > +	/* W1C */
> > +	data = musb_readw(addr, offset);
> > +	musb_writew(addr, offset, data);
> > +	return musb_readw(addr, offset);
> 
> 	return data;

Okay.

> 
> Regards,
> -Bin.