Hi Ulf, Thanks for the review.
On Tue, Jun 12, 2018 at 08:25:44AM +0200, Ulf Hansson wrote: > On 8 June 2018 at 11:51, Feng Tang <[email protected]> wrote: > > When doing some boot time optimization for an eMMC rootfs NUCs, > > we found the rootfs may spend around 100 microseconds waiting > > for eMMC card to be initialized, then the rootfs could be > > mounted. > > [ 1.216561] Waiting for root device /dev/mmcblk1p1... > > [ 1.289262] mmc1: new HS400 MMC card at address 0001 > > [ 1.289667] mmcblk1: mmc1:0001 R1J56L 14.7 GiB > > [ 1.289772] mmcblk1boot0: mmc1:0001 R1J56L partition 1 8.00 MiB > > [ 1.289869] mmcblk1boot1: mmc1:0001 R1J56L partition 2 8.00 MiB > > [ 1.289967] mmcblk1rpmb: mmc1:0001 R1J56L partition 3 4.00 MiB > > [ 1.292798] mmcblk1: p1 p2 p3 > > [ 1.300576] EXT4-fs (mmcblk1p1): couldn't mount as ext3 due to > > feature incompatibilities > > [ 1.300912] EXT4-fs (mmcblk1p1): couldn't mount as ext2 due to > > feature incompatibilities > > > > And this is a common problem for smartphones, tablets, embedded > > devices and automotive products. This patch will make the eMMC/SD > > card start initializing earlier, by changing its order in drivers/Makefile. > > > > On our platform, the waiting for eMMC card is almost eliminated with the > > patch, > > which is critical to boot time. > > I am wondering what kernel version you are running here. There have > been some changes to the mmc initialization path, which perhaps can > help. These logs in commit msg are based on kernel 4.14, and the patch is generated against kernel 4.17. > > > > > Signed-off-by: Feng Tang <[email protected]> > > --- > > drivers/Makefile | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/Makefile b/drivers/Makefile > > index 24cd47014657..c473afd3c688 100644 > > --- a/drivers/Makefile > > +++ b/drivers/Makefile > > @@ -50,6 +50,9 @@ obj-$(CONFIG_REGULATOR) += regulator/ > > # reset controllers early, since gpu drivers might rely on them to > > initialize > > obj-$(CONFIG_RESET_CONTROLLER) += reset/ > > > > +# put mmc early as many morden devices use emm/sd card as rootfs storage > > +obj-y += mmc/ > > + > > Your suggested approach isn't really a solution, as it may work for > your particular case but not for everybody else. Do you mean the patch may break some platforms? Yes, I only tested on some IA based NUCs, and I did think about other architectures, things that may affect MMC are gpio/clk/pinctrl, and those are still earlier than mmc after change. Thanks, Feng
