linux-kernel - Re: [PATCH] i2c: mediatek: fix transfer error handling

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Message-ID: <1438668829.16626.4.camel@mtksdaap41>
Date:	Tue, 4 Aug 2015 14:13:49 +0800
From:	Eddie Huang <eddie.huang@...iatek.com>
To:	Wolfram Sang <wsa@...-dreams.de>
CC:	<srv_heupstream@...iatek.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Liguo Zhang <liguo.zhang@...iatek.com>,
	Xudong Chen <xudong.chen@...iatek.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	<linux-i2c@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH] i2c: mediatek: fix transfer error handling

On Fri, 2015-07-31 at 13:00 +0200, Wolfram Sang wrote:
> On Tue, Jul 28, 2015 at 11:38:05AM +0800, Eddie Huang wrote:
> > From: Liguo Zhang <liguo.zhang@...iatek.com>
> > 
> > Reset i2c dma engine in hw init function.
> > When occur i2c ack error, mtk_i2c_irq may is twice,
> > first is the ack error interrupt, then the complete interrupt,
> > so i2c->irq_stat need keep the two interrupt value, and only
> > call complete() for the complete interrupt.
> > 
> > Signed-off-by: Liguo Zhang <liguo.zhang@...iatek.com>
> > Signed-off-by: Eddie Huang <eddie.huang@...iatek.com>
> 
> Looks to me this patch needs to be split up into one patch per issue?
OK, I can split 

> And doesn't it kill the auto_restart functionality? Sascha?

No. restart_flag already set in mtk_i2c_do_transfer() function.It is not
necessary check restart_flag again in mtk_i2c_irq(). It is simpler to
just read status bit and write back to clear interrupt status.

Eddie
Thanks

> 
> > ---
> >  drivers/i2c/busses/i2c-mt65xx.c |   25 ++++++++++++++++++-------
> >  1 file changed, 18 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
> > index 9920eef..57d11b7 100644
> > --- a/drivers/i2c/busses/i2c-mt65xx.c
> > +++ b/drivers/i2c/busses/i2c-mt65xx.c
> > @@ -59,6 +59,7 @@
> >  #define I2C_DMA_START_EN		0x0001
> >  #define I2C_DMA_INT_FLAG_NONE		0x0000
> >  #define I2C_DMA_CLR_FLAG		0x0000
> > +#define I2C_DMA_HARD_RST		0x0002
> >  
> >  #define I2C_DEFAULT_SPEED		100000	/* hz */
> >  #define MAX_FS_MODE_SPEED		400000
> > @@ -81,6 +82,7 @@ enum DMA_REGS_OFFSET {
> >  	OFFSET_INT_FLAG = 0x0,
> >  	OFFSET_INT_EN = 0x04,
> >  	OFFSET_EN = 0x08,
> > +	OFFSET_RST = 0x0c,
> >  	OFFSET_CON = 0x18,
> >  	OFFSET_TX_MEM_ADDR = 0x1c,
> >  	OFFSET_RX_MEM_ADDR = 0x20,
> > @@ -262,6 +264,10 @@ static void mtk_i2c_init_hw(struct mtk_i2c *i2c)
> >  		      I2C_CONTROL_CLK_EXT_EN | I2C_CONTROL_DMA_EN;
> >  	writew(control_reg, i2c->base + OFFSET_CONTROL);
> >  	writew(I2C_DELAY_LEN, i2c->base + OFFSET_DELAY_LEN);
> > +
> > +	writel(I2C_DMA_HARD_RST, i2c->pdmabase + OFFSET_RST);
> > +	udelay(50);
> > +	writel(I2C_DMA_CLR_FLAG, i2c->pdmabase + OFFSET_RST);
> >  }
> >  
> >  /*
> > @@ -550,16 +556,20 @@ err_exit:
> >  static irqreturn_t mtk_i2c_irq(int irqno, void *dev_id)
> >  {
> >  	struct mtk_i2c *i2c = dev_id;
> > -	u16 restart_flag = 0;
> > +	u16 intr_stat = 0;
> >  
> > -	if (i2c->dev_comp->auto_restart)
> > -		restart_flag = I2C_RS_TRANSFER;
> > +	intr_stat = readw(i2c->base + OFFSET_INTR_STAT);
> > +	writew(intr_stat, i2c->base + OFFSET_INTR_STAT);
> >  
> > -	i2c->irq_stat = readw(i2c->base + OFFSET_INTR_STAT);
> > -	writew(restart_flag | I2C_HS_NACKERR | I2C_ACKERR
> > -		| I2C_TRANSAC_COMP, i2c->base + OFFSET_INTR_STAT);
> > +	/*
> > +	 * when occurs i2c ack error, mtk_i2c_irq is called twice,
> > +	 * first is the ack error interrupt, then the complete interrupt,
> > +	 * i2c->irq_stat need keep the two interrupt value.
> > +	 */
> > +	i2c->irq_stat |= intr_stat;
> >  
> > -	complete(&i2c->msg_complete);
> > +	if (i2c->irq_stat & I2C_TRANSAC_COMP)
> > +		complete(&i2c->msg_complete);
> >  
> >  	return IRQ_HANDLED;
> >  }
> > @@ -729,3 +739,4 @@ module_platform_driver(mtk_i2c_driver);
> >  MODULE_LICENSE("GPL v2");
> >  MODULE_DESCRIPTION("MediaTek I2C Bus Driver");
> >  MODULE_AUTHOR("Xudong Chen <xudong.chen@...iatek.com>");
> > +MODULE_AUTHOR("Liguo Zhang <liguo.zhang@...iatek.com>");
> > -- 
> > 1.7.9.5
> > 


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