On Tue, May 26, 2020 at 07:17:04PM -0600, Rob Herring wrote: > On Wed, May 27, 2020 at 12:55:17AM +0300, Serge Semin wrote: > > Recently the I2C-controllers slave interface support was added to the > > kernel I2C subsystem. In this case Linux can be used as, for example, > > a I2C EEPROM machine. See [1] for details. Other than instantiating > > the EEPROM-slave device from user-space there is a way to declare the > > device in dts. In this case firstly the I2C bus controller must support > > the slave interface. Secondly I2C-slave sub-node of that controller > > must have "reg"-property with flag I2C_OWN_SLAVE_ADDRESS set (flag is > > declared in [2]). That flag is declared as (1 << 30), which when set > > makes dtc unhappy about too big address set for a I2C-slave: > > > > Warning (i2c_bus_reg): /example-2/i2c@1120000/eeprom@64: I2C bus unit address format error, expected "40000064" > > Warning (i2c_bus_reg): /example-2/i2c@1120000/eeprom@64:reg: I2C address must be less than 10-bits, got "0x40000064" > > > > Similar problem would have happened if we had set the 10-bit address > > flag I2C_TEN_BIT_ADDRESS in the "reg"-property. > > > > In order to fix the problem we suggest to alter the I2C-bus reg-check > > algorithm, so one would be aware of the upper bits set. Normally if no > > flag specified, the 7-bit address is expected in the "reg"-property. > > If I2C_TEN_BIT_ADDRESS is set, then the 10-bit address check will be > > performed. The I2C_OWN_SLAVE_ADDRESS flag will be just ignored. > > > > [1] Documentation/i2c/slave-interface.rst > > [2] include/dt-bindings/i2c/i2c.h > > > > Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx> > > Cc: Alexey Malahov <Alexey.Malahov@xxxxxxxxxxxxxxxxxxxx> > > Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> > > Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > Cc: linux-mips@xxxxxxxxxxxxxxx > > Cc: linux-i2c@xxxxxxxxxxxxxxx > > --- > > scripts/dtc/checks.c | 13 +++++++++---- > > 1 file changed, 9 insertions(+), 4 deletions(-) > > I've lost track of who all I've said this to already for this issue, but > patches to dtc should be against upstream and a version of this has been > sent there already. But it seems they've lost interest in addressing the > review comments. So feel free to send another one. The same comment > applies here. Agreed. Rob, could you also take a look at the patch [PATCH v3 03/12] dt-bindings: i2c: Discard i2c-slave flag from the DW I2C example from this series? You must have missed that. I've created that patch in accordance with your suggestion from v2: https://lore.kernel.org/linux-i2c/20200511160924.GA9628@bogus/ -Sergey > > Rob
