[U-Boot] [EXT] Re: [PATCH 1/2] dm: i2c: Add a flag that not call i2c_setup_offset

Tue Jun 4 08:50:34 UTC 2019


> -----Original Message-----
> From: Lukasz Majewski <lukma at denx.de>
> Sent: 2019年6月4日 16:19
> To: Chuanhua Han <chuanhua.han at nxp.com>
> Cc: hs at denx.de; u-boot at lists.denx.de; Biwen Li <biwen.li at nxp.com>
> 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 07:59:44 +0000
> Chuanhua Han <chuanhua.han at nxp.com> wrote:
> 
> > > -----Original Message-----
> > > From: Lukasz Majewski <lukma at denx.de>
> > > Sent: 2019年6月4日 15:56
> > > To: Chuanhua Han <chuanhua.han at nxp.com>
> > > Cc: hs at denx.de; u-boot at lists.denx.de; Biwen Li <biwen.li at nxp.com>
> > > 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 06:48:59 +0000
> > > Chuanhua Han <chuanhua.han at nxp.com> wrote:
> > >
> > > > > -----Original Message-----
> > > > > From: Lukasz Majewski <lukma at denx.de>
> > > > > Sent: 2019年6月4日 14:46
> > > > > To: Chuanhua Han <chuanhua.han at nxp.com>
> > > > > Cc: hs at denx.de; u-boot at lists.denx.de; Biwen Li
> > > > > <biwen.li at nxp.com> 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
> > > > > <chuanhua.han at nxp.com> wrote:
> > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Lukasz Majewski <lukma at denx.de>
> > > > > > > Sent: 2019年6月4日 6:08
> > > > > > > To: Chuanhua Han <chuanhua.han at nxp.com>
> > > > > > > Cc: hs at denx.de; u-boot at lists.denx.de; Biwen Li
> > > > > > > <biwen.li at nxp.com> 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
> > > > > > > <chuanhua.han at nxp.com> 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 <chuanhua.han at nxp.com>
> > > > > > > > ---
> > > > > > > > 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?
> > Because the stop signal is generated by not calling the
> > i2c_setup_offset function, this flag is used.
> 
> But the name of the flag shall be not based on particular function name. It
> shall be a generic description - like presented above:
> 
> DM_I2C_CHIP_WR_ADDRESS = 1 << 2,
> /* Send address for each write byte */
> 
> With such generic names - there is no problem if we refactor the code and
> change the function name.
> 
> I've looked closer into those two flags:
>  git grep -n "DM_I2C_CHIP_WR_ADDRESS"
> 
> drivers/rtc/ds1307.c:319:
> drivers/rtc/isl1208.c:173:
> drivers/rtc/rv3029.c:469:
> 
> It looks like those above rtc devices use it - so maybe the issue described for
> pcf2127 is also present on those devices (so those flags have been
> introduced) ?
In this way, although each byte will send the slave address, this does not correspond to the timing of pcf2127. 
Also, there is no stop signal after setting the register address.
The chip also doesn't work.
> 
> > >
> > > Also - what is byte length of send address to this device? One byte
> > > ?
> > Yes,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
> 
> 
> 
> 
> 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