Re: [PATCH 0/6] RISC-V: Add eMMC support for TH1520 boards

[Drew Fustini <dfustini@baylibre.com>]

On Fri, Sep 22, 2023 at 07:41:37PM +0800, Xi Ruoyao wrote:
> On Thu, 2023-09-21 at 18:49 -0700, Drew Fustini wrote:
> > This series adds support for the eMMC on the BeagleV Ahead and the
> > Sipeed LicheePi 4A. This allows the kernel to boot with the rootfs on
> > eMMC.
> > 
> > I tested on top of v6.6-rc2 with this config [1]. I was able to boot
> > both the Ahead [2] and LPi4a [3] from eMMC. The following prerequisites
> > are required:
> > 
> >   [PATCH v2] riscv: dts: thead: set dma-noncoherent to soc bus [4]
> > 
> > I pushed a branch [5] with this patch series and the above patch for
> > those that find a git branch easier to test.
> > 
> > Please note that only the MMC controller connected to the eMMC device
> > is enabled in the device trees for these two boards. I did not yet
> > attempt to configure and use the microSD card slot. My preference is to
> > address that in a future patch series.
> > 
> > References:
> > [1] https://gist.github.com/pdp7/5fbdcf2a65eb1abdd3a29d519c19cdd2
> > [2] https://gist.github.com/pdp7/91a801a5f8d1070c53509eda9800ad78
> > [3] https://gist.github.com/pdp7/1445c3c991e88fd69c60165cef65726a
> > [4] https://lore.kernel.org/linux-riscv/20230912072232.2455-1-jszhang@kernel.org/
> > [5] https://github.com/pdp7/linux/tree/b4/th1520-mmc
> 
> I've tested this branch and successfully booted a rootfs on Lichee Pi 4A
> eMMC with rootdelay=10.
> 
> Curiously is there some way to make it work without rootdelay?

Thank you for testing.

This is the kernel command line that I am using on both the lpi4 and
the ahead:

root=/dev/mmcblk0p3 ro rootfstype=ext4 rootwait console=ttyS0,115200

I seem to recall that before I used rootwait that there would be a VFS
oops because mmcblk0p3 didn't exist yet.

Have you tried rootwait instead of the 10 second delay?

I imagine an enforced delay would be very annoying. With "rootwait", I
don't notice any delay, it boots to the login prompt faster than I can
read the text scrolling by during boot. (my rootfs is a simple
buildroot).

thanks,
drew