Cannot Set CCDC Register

Stefan Gachter

I have the problem that writing to some of the CCDC registers of the DM355 does not affect their values. For example, I write to the HSIZE of the CCDC and immediatly after I read the HSIZE register value, but that is still the old one:

reg.addr = 0x01C70634;
reg.val = value1;
AF_APP_IOCtl(AF_APP_fdDisplayDevice, FBIO_REG_DUMP, &reg);

reg.addr = 0x01C70634;
reg.val = 0x1234;
retCode = AF_APP_IOCtl(AF_APP_fdDisplayDevice, FBIO_REG_DUMP, &reg);

value2 = reg.val;

Thus, value1 is not equal to value2. The HSIZE register is R/W. As I understood from the documentation, registers are read and writable at any time and always the latest written value is returned (for shadowed as well as busy-write registers.)

So, why might it not be possible to write a CCDC register? Or, what are the restrictions to write to a CCDC register?

Thanks for any hint!

Stefan

over 15 years ago

0 Juan Gonzales over 15 years ago

TI__Mastermind 37340 points

I am not familiar with the AF_APP_IOCtl function, but from a hardware standpoint, you are correct that there should not be any restrictions writting to this register.

0 Jeff Hayes over 15 years ago in reply to Juan Gonzales

TI__Expert 6850 points

The HSIZE can be either shadowed or busy-writable depending on CCDCFG.VDLC.

Either way, the hardware does not have any restriction on writing to the register.

You may have an issue with the function “AF_APP_IOCtl” or the way it is used.

You can use the open source tool “devmem2” for register reading and writing.

0 Stefan Gachter over 15 years ago in reply to Jeff Hayes

Intellectual 450 points

Thanks for the replies. "AF_APP_IOCtl" encapsulates the ioctl command with some error checking. I will tray to use devmem2 instead of ioctl to directly write the registers.

0 Stefan Gachter over 15 years ago in reply to Stefan Gachter

Intellectual 450 points

However, even with devmem2 the HSIZE register is not set

# ./devmem2 0x01c70634 w 0x028
/dev/mem opened.
Memory mapped at address 0x40019000.
Value at address 0x1C70634 (0x40019634): 0x0
Written 0x28; readback 0x0
# ./devmem2 0x01c70634 w
/dev/mem opened.
Memory mapped at address 0x40019000.
Value at address 0x1C70634 (0x40019634): 0x0

I am a little bit at loss... What can block the writing to the register?

0 Stefan Gachter over 15 years ago in reply to Stefan Gachter

Intellectual 450 points

But VPSSBL registers are accessible... Nobody an idea?

0 Juan Gonzales over 15 years ago in reply to Stefan Gachter

TI__Mastermind 37340 points

Can you try the utility available in this thread?

0 Jeff Hayes over 15 years ago in reply to Juan Gonzales

TI__Expert 6850 points

Is the HSIZE register the ONLY one you can not write to or is it all the CCDC registers?

0 Jeff Hayes over 15 years ago in reply to Jeff Hayes

TI__Expert 6850 points

Is there any chance that you haven't properly enabled the pixel clock to the CCDC?

0 Stefan Gachter over 15 years ago in reply to Jeff Hayes

Intellectual 450 points

Thanks for all the comments.

It seems that all the CCDC registers are affected, though I just tried to change the registers 0x01c7:0600, 0x01c7:0634, and 0x01c7:0674.

Actually, I disabled the CCDC clock, the value of 0x01c7:0004 is

CCDC_CLK = 0

and

H3A_CLK = 1

I do so, because I want to process images from RAM with H3A engine without interference from the CCDC. (I have some strange behavior of the H3A engine in combination with the CCDC, therefore I really want to make sure that CCDC does not "pollute" my processing.).

So, do I have to switch on the CCDC clock, to be able to write the registers?

(I have not yet tested regrw, still struggeling to compile it.)

0 Stefan Gachter over 15 years ago in reply to Stefan Gachter

Intellectual 450 points

Yes, indeed, if CCDC_CLK = 0, then it is not possible to wirte to the registers. Only if CCDC_CLK = 1.

Is this a general rule? If I want to write to H3A register, then H3A_CLK = 1 and so on?

0 Anshuman Saxena over 15 years ago in reply to Stefan Gachter

TI__Mastermind 19985 points

Stefan,

Yes, without CCDC_CLK register being set to 1, the registers cannot be accessed. This is a general rule for any module. If module clock does not exist, the mempry mapped registers are not accessible.

Regards,

Anshuman

0 Stefan Gachter over 15 years ago in reply to Anshuman Saxena

Intellectual 450 points

Thanks a lot for the clarification.

Regards,

Stefan

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Cannot Set CCDC Register