From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiko Schocher Date: Fri, 27 May 2011 08:04:10 +0200 Subject: [U-Boot] [PATCH 1/7] powerpc/i2c: introduce CONFIG_I2C_TWR for setting tWR value In-Reply-To: <1306452353-11611-1-git-send-email-yorksun@freescale.com> References: <1306452353-11611-1-git-send-email-yorksun@freescale.com> Message-ID: <4DDF3EDA.1030808@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hello York, York Sun wrote: > From: york > > EEPROM requires tWR for write cycle time. Since there is no other way to > poll if the internal programming ends, wait for 5ms which is the max timing > for AT24C01/02/04/08/16 by default. It can be overridden by defining > CONFIG_I2C_TWR in configuration file if the slowest device has different write > cycle time. > > Signed-off-by: York Sun > --- > README | 7 +++++++ > drivers/i2c/fsl_i2c.c | 9 +++++++++ > 2 files changed, 16 insertions(+), 0 deletions(-) > > diff --git a/README b/README > index 8bb9c8d..83a316c 100644 > --- a/README > +++ b/README > @@ -1717,6 +1717,13 @@ The following options need to be configured: > devices can use either method, but some require one or > the other. > > + CONFIG_I2C_TWR Maybe CONFIG_SYS_I2C_EEPROM_TWR is better? > + > + defining this will override the default write cycle time the default eeprom write cycle time ... > + 5ms which is the default for AT24C01/02/4/08/16. If the > + slowest I2C device has different write cycle time, this > + option should be defined. The unit is microsecond. > + > - SPI Support: CONFIG_SPI > > Enables SPI driver (so far only tested with > diff --git a/drivers/i2c/fsl_i2c.c b/drivers/i2c/fsl_i2c.c > index cb13dee..d192b2a 100644 > --- a/drivers/i2c/fsl_i2c.c > +++ b/drivers/i2c/fsl_i2c.c > @@ -42,6 +42,14 @@ > #define CONFIG_I2C_TIMEOUT 10000 > #endif > > +/* > + * tWR is the write cycle time for EEPROM device > + * in microseconds > + */ > +#ifndef CONFIG_I2C_TWR > +#define CONFIG_I2C_TWR 5000 > +#endif > + > #define I2C_READ_BIT 1 > #define I2C_WRITE_BIT 0 > > @@ -416,6 +424,7 @@ i2c_write(u8 dev, uint addr, int alen, u8 *data, int length) > if (i2c_wait4bus()) /* Wait until STOP */ > debug("i2c_write: wait4bus timed out\n"); > > + udelay(CONFIG_I2C_TWR); > if (i == length) > return 0; > Hmm.. you add this timeout in the i2c driver, which will result in adding this default 5 ms delay for *all* i2c writes, not only for eeprom devices ... why you didn;t add this timeout in cmd_eeprom, where it seems to me is the better place for it? Looking in this common/cmd_eeprom.c there is a CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS define ... is this not adequate? bye, Heiko -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany