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Date: Tue, 10 Nov 2015 08:34:16 +0800 From: Daniel Kurtz <djkurtz@...omium.org> To: Andy Shevchenko <andy.shevchenko@...il.com> Cc: Liguo Zhang <liguo.zhang@...iatek.com>, Wolfram Sang <wsa@...-dreams.de>, srv_heupstream <srv_heupstream@...iatek.com>, Matthias Brugger <matthias.bgg@...il.com>, Eddie Huang <eddie.huang@...iatek.com>, Xudong Chen <xudong.chen@...iatek.com>, Sascha Hauer <s.hauer@...gutronix.de>, Linux I2C <linux-i2c@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>, linux-mediatek@...ts.infradead.org Subject: Re: [PATCH v2 1/2] i2c: mediatek: add i2c first write then read optimization On Mon, Nov 9, 2015 at 10:25 PM, Andy Shevchenko <andy.shevchenko@...il.com> wrote: > On Mon, Nov 9, 2015 at 7:43 AM, Liguo Zhang <liguo.zhang@...iatek.com> wrote: >> For platform with auto restart support, between every transfer, >> i2c controller will trigger an interrupt and SW need to handle >> it to start new transfer. When doing write-then-read transfer, >> instead of restart mechanism, using WRRD mode to have controller >> send both transfer in one request to reduce latency. > > >> @@ -518,6 +529,16 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap, >> if (ret) >> return ret; >> >> + i2c->auto_restart = i2c->dev_comp->auto_restart; >> + >> + /* checking if we can skip restart and optimize using WRRD mode */ >> + if (i2c->auto_restart && num == 2) { >> + if (!(msgs[0].flags & I2C_M_RD) && (msgs[1].flags & I2C_M_RD) && >> + msgs[0].addr == msgs[1].addr) { > > Nitpick (optional): > > ((msgs[0].flags & msgs[1].flags) & I2C_M_RD) > ? IMHO, this makes the code less readable. Leave this to the compiler's optimizer. -Dan > >> + i2c->auto_restart = 0; >> + } >> + } > > -- > With Best Regards, > Andy Shevchenko > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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