linux-kernel - Re: [PATCH 3/4] PCI: cadence-ep: Introduce cdns_pcie_ep

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Message-ID: <itmjxj5kuy7cloeplhwqxyumcx7rrzvdudxilg6fswrtxqcl7l@oa2uvswe2ups>
Date: Wed, 9 Apr 2025 22:26:39 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Niklas Cassel <cassel@...nel.org>
Cc: Siddharth Vadapalli <s-vadapalli@...com>, lpieralisi@...nel.org, 
	kw@...ux.com, robh@...nel.org, bhelgaas@...gle.com, vigneshr@...com, 
	kishon@...nel.org, wojciech.jasko-EXT@...tinental-corporation.com, 
	thomas.richard@...tlin.com, bwawrzyn@...co.com, linux-pci@...r.kernel.org, 
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, srk@...com, dlemoal@...nel.org
Subject: Re: [PATCH 3/4] PCI: cadence-ep: Introduce cdns_pcie_ep_disable
 helper for cleanup

On Tue, Apr 01, 2025 at 01:28:51PM +0200, Niklas Cassel wrote:
> Hello Mani,
> 
> On Wed, Mar 19, 2025 at 04:02:17PM +0530, Manivannan Sadhasivam wrote:
> > > 
> > > While I don't intend to justify dropping pci_epc_deinit_notify() in the
> > > cleanup path, I wanted to check if this should be added to
> > > dw_pcie_ep_deinit() as well. Or is it the case that dw_pcie_ep_deinit()
> > > is different from cdns_pcie_ep_disable()? Please let me know.
> > > 
> > 
> > Reason why it was not added to dw_pcie_ep_deinit() because, deinit_notify() is
> > supposed to be called while performing the resource cleanup with active refclk.
> > 
> > Some plaforms (Tegra, Qcom) depend on refclk from host. So if deinit_notify() is
> > called when there is no refclk, it will crash the endpoint SoC. But since
> > cadence endpoint platforms seem to generate their own refclk, you can call
> > deinit_notify() during deinit phase.
> > 
> > That said, I noticed some issues in the DWC cleanup path while checking the code
> > now. Will submit fixes for them.
> 
> Could you please elaborate quickly what issues you found?
> 

(1)

dw_pcie_ep_deinit()
	-> dw_pcie_ep_cleanup()
		-> dw_pcie_edma_remove()

But dw_pcie_ep_init() is not calling dw_pcie_edma_detect(). It is called by
dw_pcie_ep_init_registers(). So dw_pcie_ep_init() and dw_pcie_ep_deinit() not
symmetrical.

(2)

We are not calling pci_epc_deinit_notify() in non-PREST# supported controller
drivers. I think this could be fixed by moving it inside dw_pcie_ep_cleanup().

- Mani

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