Re: [PATCH] riscv: align pcie bus assign logic with ARM64

From: Paul Walmsley <pjw@kernel.org>
To: sun.wenhan@zte.com.cn
Cc: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu,
	alex@ghiti.fr,  linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org,  liu.qingtao2@zte.com.cn,
	lv.yating@zte.com.cn, guo.chang2@zte.com.cn,
	 deng.weixian@zte.com.cn, hu.yuye@zte.com.cn
Subject: Re:  [PATCH] riscv: align pcie bus assign logic with ARM64
Date: Fri, 25 Sep 2026 17:46:38 -0600 (MDT)	[thread overview]
Message-ID: <c8bd7448-e9f3-72fc-9c91-db0c2525a3a1@kernel.org> (raw)
In-Reply-To: <202609220934.68M9Y2eC015972@mse-db.zte.com.cn>

Hi

On Tue, 22 Sep 2026, sun.wenhan@zte.com.cn wrote:

> RISC-V currently relies on the asm-generic default of
> pcibios_assign_all_busses() returning 1, so the kernel always
> re-assigns all PCI bus numbers and ignores the bus numbers already
> set up by the firmware. This has two downsides:
> 
> 1. As UEFI 2.8 has brought mature firmware support to RISC-V servers,
> the OS can trust and inherit the PCI bus enumeration done by the
> BIOS, skipping a redundant re-enumeration at boot and improving
> the boot time.
> 
> 2. The unconditional re-assignment causes bus numbering conflicts
> during PCI rescan. When a root port that is not the last one in
> the hierarchy is removed and the bus is rescanned, the kernel
> fails with:
> 
> pci_bus 0000:01: busn_res: can not insert [bus 01-ff] under
> [bus 00-ff] (conflicts with (null) [bus 02])
> 
> as reported for the same generic code in commit bd8cbe66c01d
> ("PCI: Make PCI bus renumbering configurable to avoid rescan
> conflicts").
> 
> Define pcibios_assign_all_busses() the same way as ARM64,
> so that RISC-V also preserves the bus numbers assigned by the
> firmware by default instead of always re-assigning them. This keeps
> RISC-V consistent with the other major architectures.
> 
> Signed-off-by: sun wenhan <sun.wenhan@zte.com.cn>

This patch doesn't apply -- see 
https://gist.github.com/linux-riscv-bot/4f238956cd137e576af24c32c44d3437
-- and the commit ID mentioned in the patch description doesn't appear to 
exist in mainline.  Can you please fix these issues and resend?

thanks,

- Paul

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