How does the IMX7D LCD rotate 90°?

[864535720]

Hello everyone, I am using the official MCIMX7SABRE development board. My Linux version is 4.9.88. The resolution of our screen is 1280*720. We want to achieve a 90° rotation of the screen. Does the IMX7 support 90° rotation? If you support, can you provide some reference materials?

look forward to your reply.

[ankitr_patel]

Hi 其东 刘 ,

Have you using X11 as display? Then just use xrandr command to rotate the Display. https://community.nxp.com/thread/305977 

Or if it's base on Qt then may refer i.MX6S screen rotation.

[864535720]

Hi ANKIT PATEL,

We are using the linux fb approach. At the same time we want to turn the screen rotation to the kernel for processing. I used to see the IMX6q in the forum to rotate the screen through the IPU in the kernel. I would like to ask if IMX7D can be selected by IPU.

[joanxie]

imx7 don't have IPU, you can use PXP to rotate, PXP supports rotate image for portrait or landscape support, for more detailed informaiton, you can refer to the 4.9.88 linux reference manual

[864535720]

hi,Joan Xie

Have you used PXP for screen rotation verification on IMX7D before? If so, can you provide the source code for verification?

[joanxie]

I haven't tested on the imx7d, but I tested on the imx6sx PXP, you can refer to it

https://community.nxp.com/docs/DOC-334845 

[864535720]

Hi, Joan Xie:

   I tested the pxp_v4l2_test.out program and found that the image output to the screen via the parameter was indeed rotated. Then I downloaded the imx-test test program on the forum, refer to pxp_v4l2_test.c. When I read pxp_v4l2_test.c, I found that many functions inside could not find a specific implementation. For example, the pxp_get_mem function. Can I find the specific implementation of this function?
look forward to your reply.

[joanxie]

why do you need the specific implementation of this function? I‘ve never tested this function .

[864535720]

Hi,Joan Xie

   I don't know how to make PXP rotate, so I want to refer to the test code. But just refer to the current test code, or can not let me understand how to make PXP rotate, because the current test code is used to the library. So I want to read more detailed code. Can you provide it?

[joanxie]

you can refer to the latest source code, I don't find the function you mentioned,

pxp_v4l2_test.c\pxp_v4l2_test\test - imx-test - i.MX Driver Test Application Software 

[864535720]

hi，Joan Xie

I went to read the 4.9.88 linux reference manual document you said. I looked at the code in pxp_dma_v3.c according to the introduction. Then I tracked the code inside. During the running of the code, I found that the thread created in the pxp_probe function, in its corresponding thread function, calls

wait_event_freezable(pxp->thread_waitq,Has_pending_task(pxp, pending) ||Kthread_should_stop());
Then the entire thread goes to sleep.
How can I wake up this thread?
look forward to your reply.