Re: [PATCH v6 0/4] PCI: Add support for resetting the Root Ports in a platform specific way

From: Niklas Cassel <cassel@kernel.org>
To: Manivannan Sadhasivam <mani@kernel.org>
Cc: manivannan.sadhasivam@oss.qualcomm.com,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Mahesh J Salgaonkar" <mahesh@linux.ibm.com>,
	"Oliver O'Halloran" <oohall@gmail.com>,
	"Will Deacon" <will@kernel.org>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Krzysztof Wilczyński" <kwilczynski@kernel.org>,
	"Rob Herring" <robh@kernel.org>,
	"Heiko Stuebner" <heiko@sntech.de>,
	"Philipp Zabel" <p.zabel@pengutronix.de>,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org,
	linux-arm-kernel@lists.infradead.org,
	linux-arm-msm@vger.kernel.org,
	linux-rockchip@lists.infradead.org,
	"Wilfred Mallawa" <wilfred.mallawa@wdc.com>,
	"Krishna Chaitanya Chundru" <krishna.chundru@oss.qualcomm.com>,
	"Lukas Wunner" <lukas@wunner.de>
Subject: Re: [PATCH v6 0/4] PCI: Add support for resetting the Root Ports in a platform specific way
Date: Wed, 11 Mar 2026 11:59:37 +0100	[thread overview]
Message-ID: <abFLGRn9TYrsycRs@fedora> (raw)
In-Reply-To: <mevtdhght66tds7yhmr5a6xg5a75fb667b6lyvguoxqexmc74p@mroqidhzptxk>

On Tue, Mar 10, 2026 at 07:07:39PM +0530, Manivannan Sadhasivam wrote:
> > 
> > I tested your patch series + your suggested change above, and after a:
> > 
> > ## On EP side:
> > # echo 0 > /sys/kernel/config/pci_ep/controllers/a40000000.pcie-ep/start && \
> >   sleep 0.1 && echo 1 > /sys/kernel/config/pci_ep/controllers/a40000000.pcie-ep/start
> > 
> > Instead of:
> > 
> > # FAILED: 1 / 16 tests passed.
> > 
> > I now get:
> > # FAILED: 7 / 16 tests passed.
> > 
> > Test cases 1-7 now passes (the test cases related to BARs),
> > all other test cases still fail:

(snip)

> I guess what is going wrong here is that you might be rebooting the device
> *after* restoring the config space in 'slot_reset()' callback. So all the
> previous config space contents would be lost and the device would've started
> afresh.

I'm confused.

# echo 0 > /sys/kernel/config/pci_ep/controllers/a40000000.pcie-ep/start && \
  sleep 0.1 && echo 1 > /sys/kernel/config/pci_ep/controllers/a40000000.pcie-ep/start

Will not reboot the device.

> 
> I don't think we can restore the config space after rebooting the EP device,
> because host has no idea about it. It can only restore the content after
> recovering the device through platform specific means.

Am I missing something, or why are we talking about rebooting the device?

Kind regards,
Niklas