DRA718: Guidance new driver implementations for LT8618EX

Prasad Pallapu

Part Number: DRA718
Other Parts Discussed in Thread: TPS65218

Hello,

We are using custom Dra71x processor on our custom board with 6.00.00.03 SDK of Dra7xx EVM.

We require 2 HDMI ports, but this processor supports only one HDMI.

So we have incorporated LT8168EX IC which converts the RBG to HDMI format and inputs to the HDMI connector to the display

This LT8618EX is as i2c slave.

We are a bit new to linux driver development.

Now we are confused, since it is an i2c slave does the SW driver should be written as i2c slave device or as it deals Display Subsystem should it be written as a platform driver.

Request you to guide on driver development and suggest me if we have any reference driver available to look for?

over 4 years ago

0 Brijesh Jadav over 4 years ago

TI__Guru**** 475345 points

Hi Prasad,

Does this device require any configuration? On which i2c bus this device is connected?

On Linux, you could even access the i2c bus from application space and configure the device.

Regards,

Brijesh

0 Prasad Pallapu over 4 years ago in reply to Brijesh Jadav

Intellectual 510 points

Hello Brijesh,

Thanks for the immediate reply.

Yes, it required configuration, it is connected on i2c1.

0 Brijesh Jadav over 4 years ago in reply to Prasad Pallapu

TI__Guru**** 475345 points

Hi Prasad,

Please use standard i2c utilities available on Linux. I think there is also /dev/i2c entry for each enable i2c instance. You could use it to communicate with the i2c slaves..

Checkout e2e forum like https://e2e.ti.com/support/processors-group/processors/f/processors-forum/205622/linux-usermode-i2c-utilities.

Regards,

Brijesh

0 Prasad Pallapu over 4 years ago in reply to Brijesh Jadav

Intellectual 510 points

Hello Brijesh,

But the device is RGB to HDMI converter, so i need to register it as platform device so that we can feed RGB data as input data to the device.

If that is the case how do i need to interface with interface with DSS?

0 Brijesh Jadav over 4 years ago in reply to Prasad Pallapu

TI__Guru**** 475345 points

Hello Prasad,

Yep, that's one way. You would need to add slave device for the DSS.

The other way is, just configure DSS to output RGB data and then using i2c utilities configure this device.

Regards,

Brijesh

0 Prasad Pallapu over 4 years ago in reply to Brijesh Jadav

Intellectual 510 points

Hello Brijesh,

I am able to configure the IC with i2c configurations.

Btu at the same time, i need to register it as dss device also to feed RGB data. For this do we have any mandatory APIs that has to be called from the RGB to HDMI driver to register it as omap_dss_device?

And also what are the steps to configure DSS to output RGB data?

0 Brijesh Jadav over 4 years ago in reply to Prasad Pallapu

TI__Guru**** 475345 points

Hi Prasad,

Please refer to the one of existing slave driver, you would get the idea as to what mandatory APIs are required.

Regards,

Brijesh

0 Prasad Pallapu over 4 years ago in reply to Brijesh Jadav

Intellectual 510 points

Hello Brijesh,

We need to configure i2c configurations during driver loading and configuring them from the user space may not suits out requirement.

For this, we have registered as platform device driver, but we do not have way to get the i2c client for configuring i2c slave.

Do we have any (structure) that have both platform device and i2c client bind together? or how can i get the client if i register the device as platform device?

0 Keerthy J over 4 years ago in reply to Prasad Pallapu

TI__Guru**** 162330 points

Hi Prasad,

The best forum for Linux i2c slave driver implementation:

linux-i2c@vger.kernel.org should be the best place to discuss and ask questions.

Also if you want to look at some i2c slave driver examples. PMICs are i2c slaves.
Ex driver: drivers/mfd/tps65218.c

Best Regards,
Keerthy

Processors

Processors forum

DRA718: Guidance new driver implementations for LT8618EX