linux-kernel - Re: [RESEND RFC PATCH v4 1/5] PCI: rockchip: Use standard PCIe defines

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Message-ID: <aEyRrtMZ0LidhyOR@geday>
Date: Fri, 13 Jun 2025 18:01:34 -0300
From: Geraldo Nascimento <geraldogabriel@...il.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: linux-rockchip@...ts.infradead.org,
	Shawn Lin <shawn.lin@...k-chips.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Heiko Stuebner <heiko@...ech.de>, Vinod Koul <vkoul@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	linux-phy@...ts.infradead.org, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND RFC PATCH v4 1/5] PCI: rockchip: Use standard PCIe
 defines

On Fri, Jun 13, 2025 at 03:50:23PM -0500, Bjorn Helgaas wrote:
> I don't have access to any of these TRMs, so I only know what's in the
> driver.
> 

They are not under NDA and can be obtained though Rockchip's
official site:
https://rockchip.fr/Rockchip%20RK3399%20TRM%20V1.3%20Part2.pdf

> When you say "without fear", are you saying there's a way to do that
> 32-bit write such that the LNKSTA bits are discarded by the hardware?
> Or just that the hardware forces us to accept this potential status
> register corruption?

I meant to say those registers themselves are defined in TRM as 32 bits.

> 
> Is this something that could be written using the config access path?
> I guess probably not, based on this:
> 
>   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/pcie-rockchip-host.c?id=v6.15#n141
> 

That certainly looks frightening.

> Bjorn