Re: OMAP: send i2c message ignoring NAK

[Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>]

On Tue, 3 Jul 2012 10:12:09 +0200, Yegor Yefremov wrote:
> I'm using the second i2c channel to connect to HDMI transmitter
> sii9022a. In order to get EDID information from the attached monitor
> the sii9022a chip passes i2c request direct to the monitors i2c bus.
> To return to sii9022a mode one has to write data to HDMI transmitter,
> but this data won't be acknowledged. Because of this i2c produces
> timeout permanently (omap_i2c omap_i2c.2: controller timed out), so no
> communication is possible. The last bits I see on the scope are the
> i2c address of sii9022a. The CPU automatically end the transfer.
> 
> The HDMI chip has i2c address 0x72 (8-bit notation) and EDID channel
> 0xa0 (8-bit notation). AFAIK there is only one device at a time on the
> bus, i.e. as soon as I switch sii9022a to access monitor only 0xa0
> responds to the queries. And I need to send a message to 0x72 ignoring
> normal i2c conditions in order to turn it back in normal mode.
> 
> The driver for this HDMI transmitter can be found here:
> http://gitorious.org/efikamx/linux-kernel.git
> (drivers/video/mxc/siihdmi.c)
> 
> How can I send this write request without awaiting for ACK?

Use I2C_M_IGNORE_NAK, see Documentation/i2c/i2c-protocol.

-- 
Jean Delvare