linux-kernel - Re: [PATCH v3 0/5] arm64: Initial Realtek RTD1295 enablement

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Date:   Tue, 5 Sep 2017 00:09:10 +0200
From:   Andreas Färber <afaerber@...e.de>
To:     linux-arm-kernel@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>
Cc:     devicetree@...r.kernel.org, Roc He <hepeng@...oo.tv>,
        Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
        Olof Johansson <olof@...om.net>,
        蒋丽琴 <jiang.liqin@...iatech.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>
Subject: Re: [PATCH v3 0/5] arm64: Initial Realtek RTD1295 enablement

Hi,

Am 14.05.2017 um 04:24 schrieb Andreas Färber:
> This mini-series adds initial support for the Realtek RTD1295 SoC and
> the Zidoo X9S TV box.
> 
> v3 changes #address-cells, #size-cells and ranges.
> 
> With these patches CPU0 can be booted with earlycon.
> 
> PSCI doesn't work despite present in the vendor device tree; as enable-method
> it instead used a custom "rtk-spin-table" that I sadly have no source code of.

Synology has now published source code for RTD1293/1296. This has
allowed me to narrow the RTD1295 CPU1..3 issue down to two changes in
arch/arm64/kernel/smp_spin_table.c:smp_spin_table_cpu_prepare():

1) writel_relaxed() instead of writeq_relaxed()
2) ioremap() instead of ioremap_cache()

Without those changes it hangs in earlycon after this line:
[    0.043674] Mountpoint-cache hash table entries: 4096 (order: 3,
32768 bytes)

The size difference sounds easy enough - we could introduce an optional
cpu-release-size property to handle this or derive a "spin-table-32bit"
enable-method to that effect.

The second one appears to be caused by PROT_NORMAL vs.
PROT_DEVICE_nGnRE. Is there any simple check we could do on
cpu-release-addr to choose which MT to use?

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=113954c6463d1d80a206e91627ae49711f8b47cd

Any other ideas?

[...]
> The boot process is slightly twisted: The files need to be loaded from a
> 32-bit U-Boot, then boot into 64-bit U-Boot where the kernel can be booted.
> Similar to my previous Amlogic S905 work, the TEXT_OFFSET poses a problem, so
> a uImage needs to be used (or the kernel patched) for load address 0x00280000.
> I haven't succeeded loading an initrd via bootm/booti; but as quick workaround
> initrd=$rootfs_loadaddr,0x$filesize can manually be specified in $bootargs.
> 
> Cf. https://en.opensuse.org/HCL:Zidoo_X9S
> 
> More experimental patches at:
> https://github.com/afaerber/linux/commits/rtd1295-next
[snip]

My above branch includes the above spin-table hack for now.

Regards,
Andreas

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