Re: [PATCH 0/3] PCI: designware: Fixing MSI handling flow

From: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
To: Marc Zyngier <marc.zyngier@arm.com>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Bjorn Helgaas <helgaas@google.com>
Cc: Trent Piepho <tpiepho@impinj.com>,
	Jingoo Han <jingoohan1@gmail.com>,
	Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
	"faiz_abbas@ti.com" <faiz_abbas@ti.com>,
	Joao Pinto <Joao.Pinto@synopsys.com>, Vignesh R <vigneshr@ti.com>
Subject: Re: [PATCH 0/3] PCI: designware: Fixing MSI handling flow
Date: Tue, 13 Nov 2018 23:16:33 +0000	[thread overview]
Message-ID: <e73891a5-d798-ee9c-607c-9648d07f6505@synopsys.com> (raw)
In-Reply-To: <20181113225734.8026-1-marc.zyngier@arm.com>

On 13/11/2018 22:57, Marc Zyngier wrote:
> It recently came to light that the Designware PCIe driver is rather
> broken in the way it handles MSI[1]:
> 
> - It masks interrupt by disabling them, meaning that MSIs generated
>   during the masked window are simply lost. Oops.
> 
> - Acking of the currently pending MSI is done outside of the interrupt
>   flow, getting moved around randomly and ultimately breaking the
>   driver. Not great.
> 
> This series attempts to address this by switching to using the MASK
> register for masking interrupts (!), and move the ack into the
> appropriate callback, giving it a fixed place in the MSI handling
> flow.
> 
> Note that this is only compile-tested on my arm64 laptop, as I'm
> travelling and do not have the required HW to test it anyway. I'd
> welcome both review and testing by the interested parties (dwc
> maintainer and users affected by existing bugs).

As we spoke on the conference, as soon as I get back and I've the necessary
conditions I'll test the discussed modifications on my HW.

> 
> Thanks,
> 
> 	M.
> 
> [1] https://urldefense.proofpoint.com/v2/url?u=https-3A__patchwork.kernel.org_patch_10657987_&d=DwIDAg&c=DPL6_X_6JkXFx7AXWqB0tg&r=bkWxpLoW-f-E3EdiDCCa0_h0PicsViasSlvIpzZvPxs&m=ksl4uVn2tYUOeqywcyeYHziG6ejYHFeq-Cm4p8q7amU&s=WILOPbhOsYjM3XNhZwxGb2T6069LtLL1aqf9hbS-ajg&e=
> 
> Marc Zyngier (3):
>   PCI: designware: Use interrupt masking instead of disabling
>   PCI: designware: Take lock when ACKing an interrupt
>   PCI: designware: Move interrupt acking into the proper callback
> 
>  .../pci/controller/dwc/pcie-designware-host.c | 22 ++++++++++++-------
>  1 file changed, 14 insertions(+), 8 deletions(-)
> 