linux-kernel - RE: [PATCH v6 1/2] i2c: imx: add DMA support for freescale i2c driver

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Message-ID: <c9727eaf22dc40f796793c6b127dfb9e@BL2PR03MB338.namprd03.prod.outlook.com>
Date:	Thu, 7 Aug 2014 08:04:58 +0000
From:	Yao Yuan <yao.yuan@...escale.com>
To:	"fugang.duan@...escale.com" <fugang.duan@...escale.com>,
	"wsa@...-dreams.de" <wsa@...-dreams.de>,
	"marex@...x.de" <marex@...x.de>
CC:	"LW@...O-electronics.de" <LW@...O-electronics.de>,
	"mark.rutland@....com" <mark.rutland@....com>,
	"shawn.guo@...aro.org" <shawn.guo@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"Frank.Li@...escale.com" <Frank.Li@...escale.com>
Subject: RE: [PATCH v6 1/2] i2c: imx: add DMA support for freescale i2c driver

Hi Fugang,

> >> >+	/* Waiting for Transfer complete. */
> >> >+	while (timeout--) {
> >> >+		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
> >> >+		if (temp & I2SR_ICF)
> >> >+			break;
> >> >+		udelay(10);
> >> >+	}
> >> Whether there have better method like interrupt to avoid dead wait
> >> here until timeout ?
> >
> >Can you give me more suggestion? We have discussed it with our team, It
> >seems the short query wait is necessary.
> >
> At least, you can use schdule_timeout() instead of udelay() ?

In fact, the waiting time normally is less than 10-50us, but the minimum time interval for schdule_timeout() is 1 jiffies.
So maybe schdule_timeout() is not very necessary?




Thanks for your review.

Best Regards,
Yuan Yao
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