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Date:   Fri, 22 Sep 2023 09:23:21 -0700
From:   Drew Fustini <dfustini@baylibre.com>
To:     Xi Ruoyao <xry111@xry111.site>
Cc:     Ulf Hansson <ulf.hansson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Jisheng Zhang <jszhang@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Guo Ren <guoren@kernel.org>, Fu Wei <wefu@redhat.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Conor Dooley <conor@kernel.org>,
        Robert Nelson <robertcnelson@beagleboard.org>,
        Jason Kridner <jkridner@beagleboard.org>,
        Han Gao <gaohan@iscas.ac.cn>, Icenowy Zheng <uwu@icenowy.me>,
        linux-mmc@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
Subject: Re: [PATCH 0/6] RISC-V: Add eMMC support for TH1520 boards
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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