| Message ID | 1509029285-27071-2-git-send-email-martyn@welchs.me.uk |
|---|---|
| State | Superseded |
| Delegated to: | Stefano Babic |
| Headers | show |
| Series | Add support for GE PPD | expand |
Hello Martyn, Am 26.10.2017 um 16:47 schrieb Martyn Welch: > From: Nandor Han <nandor.han@ge.com> > > Tweak the i2c transfer to work for devices that want to read data > without addressing a register. > > Signed-off-by: Nandor Han <nandor.han@ge.com> > Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk> > Cc: Heiko Schocher <hs@denx.de> > Cc: Stefano Babic <sbabic@denx.de> > Signed-off-by: Martyn Welch <martyn@welchs.me.uk> > --- > drivers/i2c/mxc_i2c.c | 25 +++++++++++++++---------- > 1 file changed, 15 insertions(+), 10 deletions(-) > > diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c > index abf1da2..01f268b 100644 > --- a/drivers/i2c/mxc_i2c.c > +++ b/drivers/i2c/mxc_i2c.c > @@ -317,16 +317,19 @@ static int i2c_init_transfer_(struct mxc_i2c_bus *i2c_bus, u8 chip, > temp |= I2CR_MTX | I2CR_TX_NO_AK; > writeb(temp, base + (I2CR << reg_shift)); > > - /* write slave address */ > - ret = tx_byte(i2c_bus, chip << 1); > - if (ret < 0) > - return ret; > - > - while (alen--) { > - ret = tx_byte(i2c_bus, (addr >> (alen * 8)) & 0xff); > + if (alen != -1) { I prefer here a "if (alen >= 0) {" Thanks! bye, Heiko
> -----Original Message----- > From: Heiko Schocher [mailto:hs@denx.de] > Sent: 31 October 2017 06:28 > To: Martyn Welch <martyn@welchs.me.uk> > Cc: u-boot@lists.denx.de; Han, Nandor (GE Healthcare) > <nandor.han@ge.com>; Martyn Welch <martyn.welch@collabora.co.uk>; > Stefano Babic <sbabic@denx.de> > Subject: EXT: Re: [PATCH 1/7] imx: mxc_i2c: tweak the i2c transfer method > > Hello Martyn, > > Am 26.10.2017 um 16:47 schrieb Martyn Welch: > > From: Nandor Han <nandor.han@ge.com> > > > > Tweak the i2c transfer to work for devices that want to read data > > without addressing a register. > > > > Signed-off-by: Nandor Han <nandor.han@ge.com> > > Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk> > > Cc: Heiko Schocher <hs@denx.de> > > Cc: Stefano Babic <sbabic@denx.de> > > Signed-off-by: Martyn Welch <martyn@welchs.me.uk> > > --- > > drivers/i2c/mxc_i2c.c | 25 +++++++++++++++---------- > > 1 file changed, 15 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c index > > abf1da2..01f268b 100644 > > --- a/drivers/i2c/mxc_i2c.c > > +++ b/drivers/i2c/mxc_i2c.c > > @@ -317,16 +317,19 @@ static int i2c_init_transfer_(struct mxc_i2c_bus > *i2c_bus, u8 chip, > > temp |= I2CR_MTX | I2CR_TX_NO_AK; > > writeb(temp, base + (I2CR << reg_shift)); > > > > - /* write slave address */ > > - ret = tx_byte(i2c_bus, chip << 1); > > - if (ret < 0) > > - return ret; > > - > > - while (alen--) { > > - ret = tx_byte(i2c_bus, (addr >> (alen * 8)) & 0xff); > > + if (alen != -1) { > > I prefer here a "if (alen >= 0) {" In normal cases yes. It looks that i2c framework doesn't support requesting data from i2c without addressing the slave. In this case -1 is used to specify that address is not needed. > > Thanks! > > bye, > Heiko > -- > DENX Software Engineering GmbH, Managing Director: Wolfgang Denk > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany > Phone: +49-8142-66989-52 Fax: +49-8142-66989-80 Email: hs@denx.de
diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c index abf1da2..01f268b 100644 --- a/drivers/i2c/mxc_i2c.c +++ b/drivers/i2c/mxc_i2c.c @@ -317,16 +317,19 @@ static int i2c_init_transfer_(struct mxc_i2c_bus *i2c_bus, u8 chip, temp |= I2CR_MTX | I2CR_TX_NO_AK; writeb(temp, base + (I2CR << reg_shift)); - /* write slave address */ - ret = tx_byte(i2c_bus, chip << 1); - if (ret < 0) - return ret; - - while (alen--) { - ret = tx_byte(i2c_bus, (addr >> (alen * 8)) & 0xff); + if (alen != -1) { + /* write slave address */ + ret = tx_byte(i2c_bus, chip << 1); if (ret < 0) return ret; + + while (alen--) { + ret = tx_byte(i2c_bus, (addr >> (alen * 8)) & 0xff); + if (ret < 0) + return ret; + } } + return 0; } @@ -537,9 +540,11 @@ static int bus_i2c_read(struct mxc_i2c_bus *i2c_bus, u8 chip, u32 addr, if (ret < 0) return ret; - temp = readb(base + (I2CR << reg_shift)); - temp |= I2CR_RSTA; - writeb(temp, base + (I2CR << reg_shift)); + if (alen != -1 ) { + temp = readb(base + (I2CR << reg_shift)); + temp |= I2CR_RSTA; + writeb(temp, base + (I2CR << reg_shift)); + } ret = tx_byte(i2c_bus, (chip << 1) | 1); if (ret < 0) {