I have an i.MX8MP board (Phytec phycore to be precise) and am building a custom yocto recipe.
I am adding an second MMC on usdhc1 (mmc0)
I unfortunately have some communication problems and would like to have more MMC debugging data.
I enabled CONFIG_MMC_DEBUG in my fragment.cfg (and checked it was applied in my build directory)
Unfortunately I have no extra messages in dmeg / run/log/journal (using klog for logging)
is there another option that needs to be activated to see mmc debugging messages?
Thank you for your help!
There are a number of options in your menuconfig -> bitbake linux-imx -c menuconfig (or some kernel name). Check -> Device drivers -> MMC/SD/SDIO support -> [*] MMC host drivers debugging
<help> CONFIG_MMC_DEBUG: This enables MMC host driver debugging. There's some other debug stuff in there as well.
Worst case there's printk which can be added like printf in drivers and that woud require enabling under 'kernel hacking'. Inside 'kernel hacking' there are lots of other debugging options in there as well.
After any changes do a rebuild. Beware kernel changes can be lost after kernel cleans etc..
Check dmesg as well for kernel info..
Hope any of this helps.