EDID Header Check Issue in intel_hdmi21_tx_edid_get_sink_status() function for intel_hdmi21 driver

[dscully]

Hi,

I'd like to report a bug in the intel_hdmi21 driver as of Quartus Pro 23.2

See: intelFPGA_pro/23.2/ip/altera/altera_hdmi/hw_demo/common/software/software_driver/intel_hdmi21_tx/src/intel_hdmi21_tx_edid.c

 Consider the following function:

int intel_hdmi21_tx_edid_get_sink_status(intel_hdmi21_tx_instance_t* instance, uint8_t* edid_header_valid, uint32_t* edid_size)
{
    if (instance == NULL)
        return intel_hdmi_invalid_instance;
    if((edid_header_valid == NULL) || (edid_size == NULL))
        return intel_hdmi_invalid_arguments;

    uint32_t headerSize = 8;
    (*edid_header_valid) = 1;
    (*edid_size) = 0;
    for(uint32_t i = 0; i < headerSize; i++)
    {
        uint8_t val = edid_read_sink_reg(i);
        (*edid_header_valid) &= (((i == 0 || i == (headerSize - 1)) && val == 0) || (val == 0xFF)) ? 1 : 0;
    }

    if((*edid_header_valid))
    {
        const uint32_t numberOfExtensionsOffset = 126;
        uint32_t numberOfExtensions = edid_read_sink_reg(numberOfExtensionsOffset);
        (*edid_size) = (numberOfExtensions + 1) * INTEL_HDMI_EDID_BLOCK_SIZE;
    }

    return intel_hdmi_success;
}

The edid_head_valid check on 14 should only pass on a valid on the EDID header pattern of "00 FF FF FF FF FF FF 00". However, but will also pass a pattern of all 0xFF or a 0xFF in the first or last position due to the second logical OR in the expression.

Passing on all 0xFF is especially problematic as reading a I2C bus with an non-responding EDID device returns 0xFF for every byte. The result of the failure is that the header is declared valid and the EDID size is reported as 128 * 255.

The expected behavior is that the valid flag will be set properly.

Please let me know if there is a more appropriate place to report issues against the Intel FPGA BSP drivers.

Thank you,

David

[dscully]

A possible fix would be to change:

(*edid_header_valid) &= (((i == 0 || i == (headerSize - 1)) && val == 0) || (val == 0xFF)) ? 1 : 0;

to

(*edid_header_valid) &= (((i == 0 || i == (headerSize - 1))) ? (val == 0) : (val == 0xFF)) ? 1 : 0;

[ZH_Intel]

Hi David,

Thank you for reaching out.

Just to let you know that Intel has received your support request and currently we are confirming the details with our internal team.

I shall come back to you with findings.

Thank you for your patience.

Best Regards,

ZulsyafiqH_Intel

[ZH_Intel · Accepted solution]

Hi David,

Thank you for your patience.

Based on the discussion with our internal team, I believe that this is a bug and your concern is correct.

I will reported this to our internal team to be fix in future release.

This fix that you suggested is a valid fix/workaround for this issue.

Thank you.

Best Regards,

ZulsyafiqH_Intel

[dscully]

Thank you! I have marked this topic as resolved.

[ZH_Intel]

Hi David,

I’m glad that your question has been addressed, I now transition this thread to community support. If you have a new question, feel free to open a new thread to get the support from Intel experts. Otherwise, the community users will continue to help you on this thread.

Thank you.

Best Regards,

ZulsyafiqH_Intel