Hi Wolfram, I have observed the following behaviour in renesas-devel-20171130-v4.15-rc1 which I have bisected down to being caused by d3decc2c34c8 ("arm64: dts: renesas: salvator: set driver type for eMMC"). The patch in question is based on v4.15-rc1.
I am compiling using renesas_defconfig The problem manifests on Salvator-X / H3 ES1.0. [ 2.567304] renesas_sdhi_internal_dmac ee140000.sd: mmc0 base at 0xee140000 max clock rate 200 MHz [ 2.700110] mmc0: tuning execution failed: -5 [ 2.704591] mmc0: error -5 whilst initialising MMC card [ 2.783042] mmc0: tuning execution failed: -5 [ 2.783057] mmc0: error -5 whilst initialising MMC card [ 2.935219] mmc0: tuning execution failed: -5 [ 2.939676] mmc0: error -5 whilst initialising MMC card [ 3.103876] renesas_sdhi_internal_dmac ee100000.sd: mmc1 base at 0xee100000 max clock rate 200 MHz [ 3.174033] mmc0: tuning execution failed: -5 The behaviour on Salvator-XS / H3 ES2.0 seems inconsistent. And on Salvator-X / M3-W ES1.0 I do not see the problem regardless of the presence of the patch.