| Message ID | 20190211132515.24163-1-wsa+renesas@sang-engineering.com |
|---|---|
| State | New |
| Headers | show |
| Series | i2c: document the SDA hold time binding | expand |
On Mon, Feb 11, 2019 at 02:25:15PM +0100, Wolfram Sang wrote: > The documentation was forgotten when the feature was added. > > Fixes: 4717be73c284 ("i2c: core: Parse SDA hold time from firmware") > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> > --- > > To everyone on CC: I want to confirm here that you use the value really for > t(hd:sta) and not t(hd:dat). I'd be a little confused otherwise... +Cc: Jarkko > > Documentation/devicetree/bindings/i2c/i2c.txt | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt > index 44efafdfd7f5..b7bc4c4cc2e6 100644 > --- a/Documentation/devicetree/bindings/i2c/i2c.txt > +++ b/Documentation/devicetree/bindings/i2c/i2c.txt > @@ -55,6 +55,10 @@ wants to support one of the below features, it should adapt the bindings below. > Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C > specification. > > +- i2c-sda-hold-time-ns > + Number of nanoseconds the SDA signal needs to be held; t(hd:sta) in > + the I2C specification. > + > - interrupts > interrupts used by the device. > > -- > 2.11.0 >
Hi Wolfram, On Mon, Feb 11, 2019 at 02:25:15PM +0100, Wolfram Sang wrote: > The documentation was forgotten when the feature was added. > > Fixes: 4717be73c284 ("i2c: core: Parse SDA hold time from firmware") > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> > --- > > To everyone on CC: I want to confirm here that you use the value really for > t(hd:sta) and not t(hd:dat). I'd be a little confused otherwise... No in our case, it's t(hd:dat): TWD is kept unchanged after TWCK falling edge for a period of (HOLD + 3) × t peripheral clock Ludovic > > Documentation/devicetree/bindings/i2c/i2c.txt | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt > index 44efafdfd7f5..b7bc4c4cc2e6 100644 > --- a/Documentation/devicetree/bindings/i2c/i2c.txt > +++ b/Documentation/devicetree/bindings/i2c/i2c.txt > @@ -55,6 +55,10 @@ wants to support one of the below features, it should adapt the bindings below. > Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C > specification. > > +- i2c-sda-hold-time-ns > + Number of nanoseconds the SDA signal needs to be held; t(hd:sta) in > + the I2C specification. > + > - interrupts > interrupts used by the device. > > -- > 2.11.0 >
Sorry I didn't keep the addition of Jarkko to the CC list. On Wed, Feb 13, 2019 at 11:24:37AM +0100, Ludovic Desroches wrote: > Hi Wolfram, > > On Mon, Feb 11, 2019 at 02:25:15PM +0100, Wolfram Sang wrote: > > The documentation was forgotten when the feature was added. > > > > Fixes: 4717be73c284 ("i2c: core: Parse SDA hold time from firmware") > > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> > > --- > > > > To everyone on CC: I want to confirm here that you use the value really for > > t(hd:sta) and not t(hd:dat). I'd be a little confused otherwise... > > > No in our case, it's t(hd:dat): > TWD is kept unchanged after TWCK falling edge for a > period of (HOLD + 3) × t peripheral clock > > > Ludovic > > > > > Documentation/devicetree/bindings/i2c/i2c.txt | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt > > index 44efafdfd7f5..b7bc4c4cc2e6 100644 > > --- a/Documentation/devicetree/bindings/i2c/i2c.txt > > +++ b/Documentation/devicetree/bindings/i2c/i2c.txt > > @@ -55,6 +55,10 @@ wants to support one of the below features, it should adapt the bindings below. > > Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C > > specification. > > > > +- i2c-sda-hold-time-ns > > + Number of nanoseconds the SDA signal needs to be held; t(hd:sta) in > > + the I2C specification. > > + > > - interrupts > > interrupts used by the device. > > > > -- > > 2.11.0 > >
On Mon, Feb 11, 2019 at 02:25:15PM +0100, Wolfram Sang wrote: > The documentation was forgotten when the feature was added. > > Fixes: 4717be73c284 ("i2c: core: Parse SDA hold time from firmware") > Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> > --- > > To everyone on CC: I want to confirm here that you use the value really for > t(hd:sta) and not t(hd:dat). I'd be a little confused otherwise... I guess in our case it's also t(hd:dat). Jarkko? > > Documentation/devicetree/bindings/i2c/i2c.txt | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt > index 44efafdfd7f5..b7bc4c4cc2e6 100644 > --- a/Documentation/devicetree/bindings/i2c/i2c.txt > +++ b/Documentation/devicetree/bindings/i2c/i2c.txt > @@ -55,6 +55,10 @@ wants to support one of the below features, it should adapt the bindings below. > Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C > specification. > > +- i2c-sda-hold-time-ns > + Number of nanoseconds the SDA signal needs to be held; t(hd:sta) in > + the I2C specification. > + > - interrupts > interrupts used by the device. > > -- > 2.11.0 >
On 3/18/19 12:35 PM, Andy Shevchenko wrote: > On Mon, Feb 11, 2019 at 02:25:15PM +0100, Wolfram Sang wrote: >> The documentation was forgotten when the feature was added. >> >> Fixes: 4717be73c284 ("i2c: core: Parse SDA hold time from firmware") >> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> >> --- >> >> To everyone on CC: I want to confirm here that you use the value really for >> t(hd:sta) and not t(hd:dat). I'd be a little confused otherwise... > > I guess in our case it's also t(hd:dat). > The DesignWare specification I have mention only tHD;DAT.
diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt index 44efafdfd7f5..b7bc4c4cc2e6 100644 --- a/Documentation/devicetree/bindings/i2c/i2c.txt +++ b/Documentation/devicetree/bindings/i2c/i2c.txt @@ -55,6 +55,10 @@ wants to support one of the below features, it should adapt the bindings below. Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C specification. +- i2c-sda-hold-time-ns + Number of nanoseconds the SDA signal needs to be held; t(hd:sta) in + the I2C specification. + - interrupts interrupts used by the device.
The documentation was forgotten when the feature was added. Fixes: 4717be73c284 ("i2c: core: Parse SDA hold time from firmware") Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> --- To everyone on CC: I want to confirm here that you use the value really for t(hd:sta) and not t(hd:dat). I'd be a little confused otherwise... Documentation/devicetree/bindings/i2c/i2c.txt | 4 ++++ 1 file changed, 4 insertions(+)