RPI4's SDHCI controller is supported SDMA mode. (Checked on kernel side) But It doesn't use on u-boot side. Then it's too slow about read/write performance. This patchset is supported SDMA mode on RPI4 target(32bit). - I didn't test on RPI4 64bit.
Read/write time about 8MB file Before - Read : 1.472 seconds - Write : 4.690 seconds After - Read : 0.359 seconds - Write : 0.574 seconds
Jaehoon Chung (4): mmc: bcm2835_sdhci: use phys2bus macro when dma address is accessed mmc: sdhci: add quriks relevant to broken SDMA mmc: bcm2835_sdhci: set SDHCI_QUIRK_BROKEN_SDMA flag configs: rpi_4_32b_defconfig: enable SDHCI_SDMA config
configs/rpi_4_32b_defconfig | 1 + drivers/mmc/bcm2835_sdhci.c | 10 ++++++++-- drivers/mmc/sdhci.c | 10 ++++++++-- include/sdhci.h | 1 + 4 files changed, 18 insertions(+), 4 deletions(-)