linux-kernel - Re: [RFC PATCH] PCI: rockchip: fix system hang up if activate CONFIG_DEBUG

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Date:   Thu, 10 Aug 2017 16:39:59 +0800
From:   jeffy <jeffy.chen@...k-chips.com>
To:     Shawn Lin <shawn.lin@...k-chips.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Thomas Gleixner <tglx@...utronix.de>
CC:     Heiko Stuebner <heiko@...ech.de>, linux-pci@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        Brian Norris <briannorris@...omium.org>
Subject: Re: [RFC PATCH] PCI: rockchip: fix system hang up if activate CONFIG_DEBUG_SHIRQ

Hi shawn,

On 08/10/2017 04:21 PM, Shawn Lin wrote:
> With CONFIG_DEBUG_SHIRQ enabled, the irq tear down routine
> would still access the irq handler registed as a shard irq.
> Per the comment within the function of __free_irq, it says
> "It's a shared IRQ -- the driver ought to be prepared for
> an IRQ event to happen even now it's being freed". However
> when failing to probe the driver, it may disable the clock
> for accessing the register and the following check for shared
> irq state would call the irq handler which accesses the register
> w/o the clk enabled. That will hang the system forever.

i think this extra irq call is to make sure it's safe to get a shared 
irq when we are freeing it, and we would not get this irq after freed it.

so maybe just call devm_free_irq before disable clks(and other required 
resources for the irq handler)? and also do it in the rockchip_pcie_remove.