R-Car boards use GPIO for SD card detection, not use built-in card detection pin, because we have some reasons:
- Old Renesas SoCs don't have built-in card detection pin.
- So, for consistency and reliability, we use GPIO for SD card detection on R-Car boards.
- Using GPIO is an advantage for power management (clock gating and/or power domain) of SDHI modules.
- If we use built-in card detection pin, we have to turn the SDHI module on anyway.
The TMIO core supports built-in card detection by using the following commits.
c7cd630a9751 mmc: tmio: fix never-detected card insertion bug 497d1f965c20 mmc: tmio: support IP-builtin card detection logic