Hi Tomas, Thanks for the patch. Looks mostly fine, but this needs fixing: On Wed, Mar 20, 2024 at 01:55:38PM +0100, Tomas Marek wrote: > +static int efi_i2c_xfer(struct i2c_adapter *adapter, > + struct i2c_msg *msg, int nmsgs) > +{ > + struct efi_i2c_priv *i2c_priv = adapter_to_efi_i2c_priv(adapter); > + int i, ret; > + > + for (i = nmsgs; i > 0; i--, msg++) { > + ret = efi_i2c_message_xfer(i2c_priv, msg); > + if (ret) > + return ret; > + } Each of the messages should start with a (repeated) start bit and only the last message should be followed by a stop bit. By separating the full message into segments and pushing each segment into EFI separately you would instead send a stop bit after each segment, see the comment above EFI_I2C_REQUEST_PACKET: /// /// I2C device request /// /// The EFI_I2C_REQUEST_PACKET describes a single I2C transaction. The /// transaction starts with a start bit followed by the first operation /// in the operation array. Subsequent operations are separated with /// repeated start bits and the last operation is followed by a stop bit /// which concludes the transaction. Each operation is described by one /// of the elements in the Operation array. /// Instead you have to compile all nmsgs into a single EFI_I2C_REQUEST_PACKET and push it into EFI as a single request. Sascha -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |