From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukasz Majewski Date: Tue, 4 Jun 2019 09:56:02 +0200 Subject: [U-Boot] [EXT] Re: [PATCH 1/2] dm: i2c: Add a flag that not call i2c_setup_offset In-Reply-To: References: <20190530103149.4176-1-chuanhua.han@nxp.com> <20190604000811.2b36f78e@jawa> <20190604084607.7b05ddda@jawa> Message-ID: <20190604095602.7632841b@jawa> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: u-boot@lists.denx.de On Tue, 4 Jun 2019 06:48:59 +0000 Chuanhua Han wrote: > > -----Original Message----- > > From: Lukasz Majewski > > Sent: 2019年6月4日 14:46 > > To: Chuanhua Han > > Cc: hs at denx.de; u-boot at lists.denx.de; Biwen Li > > Subject: Re: [EXT] Re: [U-Boot] [PATCH 1/2] dm: i2c: Add a flag > > that not call i2c_setup_offset > > > > On Tue, 4 Jun 2019 02:20:49 +0000 > > Chuanhua Han wrote: > > > > > > -----Original Message----- > > > > From: Lukasz Majewski > > > > Sent: 2019年6月4日 6:08 > > > > To: Chuanhua Han > > > > Cc: hs at denx.de; u-boot at lists.denx.de; Biwen Li > > > > Subject: [EXT] Re: [U-Boot] [PATCH 1/2] dm: > > > > i2c: Add a flag that not call i2c_setup_offset > > > > > > > > On Thu, 30 May 2019 18:31:48 +0800 > > > > Chuanhua Han wrote: > > > > > > > > > Usually the i2c bus needs to write the address of the register > > > > > before reading the internal register data of the device > > > > > (ignoring the transmission of the slave address). > > > > > > > > > > Generally, the stop signal is not needed before the register > > > > > is read, but there is a special chip that needs this stop > > > > > signal (such as pcf2127). However, in the current i2c general > > > > > code, the dm_i2c_read api encapsulates two messages, the > > > > > first time is to set the register address message, the second > > > > > time is a message to read the register data, so that no stop > > > > > signal is generated. > > > > > > > > > > This patch uses the DM_I2C_CHIP_RD_NO_I2C_SETUP_OFFSET flag > > > > > for specific i2c chips, so if the i2c slave requires a stop > > > > > signal, chips driver can set this flag, then call the > > > > > dm_i2c_write to set the register address (a stop signal is > > > > > generated after this API call), then call dm_i2c_read to read > > > > > the register data. > > > > > > > > > > Signed-off-by: Chuanhua Han > > > > > --- > > > > > Changes in v3: > > > > > - Use the new flag DM_I2C_CHIP_RD_NO_I2C_SETUP_OFFSET > > > > > > > > > > Changes in v2: > > > > > - Split the original patch into 3 patches > > > > > - Add detailed description information for each patch > > > > > > > > > > drivers/i2c/i2c-uclass.c | 6 ++++-- > > > > > include/i2c.h | 1 + > > > > > 2 files changed, 5 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/drivers/i2c/i2c-uclass.c > > > > > b/drivers/i2c/i2c-uclass.c index e47abf1833..9804b5e8c7 100644 > > > > > --- a/drivers/i2c/i2c-uclass.c > > > > > +++ b/drivers/i2c/i2c-uclass.c > > > > > @@ -135,8 +135,10 @@ int dm_i2c_read(struct udevice *dev, uint > > > > > offset, uint8_t *buffer, int len) if (chip->flags & > > > > > DM_I2C_CHIP_RD_ADDRESS) return i2c_read_bytewise(dev, offset, > > > > > buffer, len); ptr = msg; > > > > > - if (!i2c_setup_offset(chip, offset, offset_buf, ptr)) > > > > > - ptr++; > > > > > + if (!(chip->flags & > > > > > DM_I2C_CHIP_RD_NO_I2C_SETUP_OFFSET)) { > > > > > + if (!i2c_setup_offset(chip, offset, > > > > > offset_buf, ptr)) > > > > > + ptr++; > > > > > + } > > > > > > > > > > if (len) { > > > > > ptr->addr = chip->chip_addr; > > > > > diff --git a/include/i2c.h b/include/i2c.h index > > > > > a5c760c711..3123cbf280 100644 > > > > > --- a/include/i2c.h > > > > > +++ b/include/i2c.h > > > > > @@ -28,6 +28,7 @@ enum dm_i2c_chip_flags { > > > > > DM_I2C_CHIP_10BIT = 1 << 0, > > > > > /* Use 10-bit addressing */ > > > > > DM_I2C_CHIP_RD_ADDRESS = 1 << 1, > > > > > /* Send address for each read byte */ > > > > > DM_I2C_CHIP_WR_ADDRESS = 1 << 2, > > > > > /* Send address for each write byte */ > > > > > > > > Aren't those two above flags describe exactly what you need? > > > > They send address for each read/written byte. (or do you need > > > > to send more than a single byte)? > > > This is not what I need. I need to generate a stop signal after > > > setting the register address, > > > > Please correct me if I'm wrong, but the above flag says that you > > need to send the I2C stop after you send one byte? > > > > Would it be possible to send address with I2C stop and then read > > data (single byte) with I2C stop? > > > > > so I need the following flag. > > > > > > > > > DM_I2C_CHIP_RD_NO_I2C_SETUP_OFFSET = 1 << 3, > > > > I do find this name as a bit misleading - is the > > RD_NO_I2C_SETUP_OFFSET name reflecting the purpose (to send I2C > > stop after sending address)? > The purpose is to send a stop signal after setting the slave register > address. What I'm trying to point out is that the above description doesn't match the flag name. Maybe there is a better, more descriptive name? Also - what is byte length of send address to this device? One byte ? > > > > Maybe there would be a better name? > > > > > > > /* No i2c_setup_offset*/ }; > > > > > > > > > > struct udevice; > > > > > > > > > > > > > > > > > > > > Best regards, > > > > > > > > Lukasz Majewski > > > > > > > > -- > > > > > > > > DENX Software Engineering GmbH, Managing Director: Wolfgang > > > > Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 > > > > Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax: > > > > (+49)-8142-66989-80 Email: lukma at denx.de > > > > > > > > > > Best regards, > > > > Lukasz Majewski > > > > -- > > > > DENX Software Engineering GmbH, Managing Director: Wolfgang > > Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, > > Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: > > lukma at denx.de Best regards, Lukasz Majewski -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma at denx.de -------------- next part -------------- A non-text attachment was scrubbed... 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