From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Zhao Subject: Re: [PATCH 2/4] i2c: imx: only imx1 needs disable delay Date: Thu, 1 Oct 2009 15:52:15 +0800 Message-ID: <4e090d470910010052k37a0a4eep6d436e45e6524234@mail.gmail.com> References: <1254359613-21210-1-git-send-email-linuxzsc@gmail.com> <1254359613-21210-2-git-send-email-linuxzsc@gmail.com> <20091001072643.GW27039@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20091001072643.GW27039@pengutronix.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Sascha Hauer Cc: linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org, kernel@pengutronix.de, w.sang@pengutronix.de List-Id: linux-i2c@vger.kernel.org On Thu, Oct 1, 2009 at 3:26 PM, Sascha Hauer wrote: > On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote: >> check cpu_is_mx1() when set disable_delay. >> >> Signed-off-by: Richard Zhao >> >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c >> index 156cc95..c1e541c 100644 >> --- a/drivers/i2c/busses/i2c-imx.c >> +++ b/drivers/i2c/busses/i2c-imx.c >> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_= struct *i2c_imx, >> =A0 =A0 =A0 /* Write divider value to register */ >> =A0 =A0 =A0 writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR); >> >> - =A0 =A0 /* >> - =A0 =A0 =A0* There dummy delay is calculated. >> - =A0 =A0 =A0* It should be about one I2C clock period long. >> - =A0 =A0 =A0* This delay is used in I2C bus disable function >> - =A0 =A0 =A0* to fix chip hardware bug. >> - =A0 =A0 =A0*/ >> - =A0 =A0 i2c_imx->disable_delay =3D (500000U * i2c_clk_div[i][0] >> - =A0 =A0 =A0 =A0 =A0 =A0 + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2); >> + =A0 =A0 if (cpu_is_mx1()) { >> + =A0 =A0 =A0 =A0 =A0 =A0 /* >> + =A0 =A0 =A0 =A0 =A0 =A0 =A0* There dummy delay is calculated. >> + =A0 =A0 =A0 =A0 =A0 =A0 =A0* It should be about one I2C clock period l= ong. >> + =A0 =A0 =A0 =A0 =A0 =A0 =A0* This delay is used in I2C bus disable fun= ction >> + =A0 =A0 =A0 =A0 =A0 =A0 =A0* to fix chip hardware bug. >> + =A0 =A0 =A0 =A0 =A0 =A0 =A0*/ >> + =A0 =A0 =A0 =A0 =A0 =A0 i2c_imx->disable_delay =3D (500000U * i2c_clk_= div[i][0] >> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 + (i2c_clk_rate / 2) - 1) / (i= 2c_clk_rate / 2); >> + =A0 =A0 } > > I think you should put the udelay(i2c_imx->disable_delay) in > cpu_is_mx1() rather than the calculation. > > Sascha > > > -- > Pengutronix e.K. =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 | = =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 | > Industrial Linux Solutions =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 | http://www.p= engutronix.de/ =A0| > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 =A0= =A0| > Amtsgericht Hildesheim, HRA 2686 =A0 =A0 =A0 =A0 =A0 | Fax: =A0 +49-5121-= 206917-5555 | > Do you think udelay(0) wast any more time than if()? And Could I get all you comments in a single patch loop? Thanks Richard From mboxrd@z Thu Jan 1 00:00:00 1970 From: linuxzsc@gmail.com (Richard Zhao) Date: Thu, 1 Oct 2009 15:52:15 +0800 Subject: [PATCH 2/4] i2c: imx: only imx1 needs disable delay In-Reply-To: <20091001072643.GW27039@pengutronix.de> References: <1254359613-21210-1-git-send-email-linuxzsc@gmail.com> <1254359613-21210-2-git-send-email-linuxzsc@gmail.com> <20091001072643.GW27039@pengutronix.de> Message-ID: <4e090d470910010052k37a0a4eep6d436e45e6524234@mail.gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Oct 1, 2009 at 3:26 PM, Sascha Hauer wrote: > On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote: >> check cpu_is_mx1() when set disable_delay. >> >> Signed-off-by: Richard Zhao >> >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c >> index 156cc95..c1e541c 100644 >> --- a/drivers/i2c/busses/i2c-imx.c >> +++ b/drivers/i2c/busses/i2c-imx.c >> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx, >> ? ? ? /* Write divider value to register */ >> ? ? ? writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR); >> >> - ? ? /* >> - ? ? ?* There dummy delay is calculated. >> - ? ? ?* It should be about one I2C clock period long. >> - ? ? ?* This delay is used in I2C bus disable function >> - ? ? ?* to fix chip hardware bug. >> - ? ? ?*/ >> - ? ? i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0] >> - ? ? ? ? ? ? + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2); >> + ? ? if (cpu_is_mx1()) { >> + ? ? ? ? ? ? /* >> + ? ? ? ? ? ? ?* There dummy delay is calculated. >> + ? ? ? ? ? ? ?* It should be about one I2C clock period long. >> + ? ? ? ? ? ? ?* This delay is used in I2C bus disable function >> + ? ? ? ? ? ? ?* to fix chip hardware bug. >> + ? ? ? ? ? ? ?*/ >> + ? ? ? ? ? ? i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0] >> + ? ? ? ? ? ? ? ? ? ? + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2); >> + ? ? } > > I think you should put the udelay(i2c_imx->disable_delay) in > cpu_is_mx1() rather than the calculation. > > Sascha > > > -- > Pengutronix e.K. ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ? ? ? ? ? ? ? ? ? ? ? ? ? | > Industrial Linux Solutions ? ? ? ? ? ? ? ? | http://www.pengutronix.de/ ?| > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 ? ?| > Amtsgericht Hildesheim, HRA 2686 ? ? ? ? ? | Fax: ? +49-5121-206917-5555 | > Do you think udelay(0) wast any more time than if()? And Could I get all you comments in a single patch loop? Thanks Richard