linux-kernel - Re: gm45 intel gfx can generate non-MSI irq# in MSI mode (was Re: [PATCH] drm/i915: stop using GMBUS IRQs on Gen4 chips (was Re: [3.9-rc1] irq 16: nobody cared (was [3.9-rc1] very poor interrupt responses

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Date:	Tue, 19 Mar 2013 12:14:39 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Daniel Vetter <daniel.vetter@...ll.ch>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	Chris Wilson <chris@...is-wilson.co.uk>,
	Jiri Kosina <jkosina@...e.cz>, Greg KH <greg@...ah.com>,
	Harald Arnesen <skogtun.linux@...il.com>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Peter Hurley <peter@...leysoftware.com>,
	Thomas Meyer <thomas@...3r.de>,
	Shawn Starr <shawn.starr@...ers.com>,
	USB list <linux-usb@...r.kernel.org>,
	linux-acpi@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-pci@...r.kernel.org, Imre Deak <imre.deak@...el.com>,
	Daniel Kurtz <djkurtz@...omium.org>,
	dri-devel@...ts.freedesktop.org,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Arkadiusz Miskiewicz <a.miskiewicz@...il.com>
Subject: Re: gm45 intel gfx can generate non-MSI irq# in MSI mode (was Re:
 [PATCH] drm/i915: stop using GMBUS IRQs on Gen4 chips (was Re: [3.9-rc1] irq
 16: nobody cared (was [3.9-rc1] very poor interrupt responses

On Tue, Mar 19, 2013 at 9:54 AM, Daniel Vetter <daniel.vetter@...ll.ch> wrote:

> I guess I should have phrased it more precisely, but that's exactly
> what I expect is happening on my machine: I don't have anything on
> irq16 (i.e. in non-msi mode the gfx interrupt isn't shared) and hence
> the irq is completely disabled. Which obviously makes it impossible
> for me to reproduce the issue. To test that theory, is there a quick
> way to force-enable a given interrupt, short of just hacking up a 2nd
> dummy irq handler in my driver?

You may try to add another request_irq()
after i915_load_modeset_init==>drm_irq_install.
That could install one dummy action for ioapic irq for i915.

Also you may need to add one quirk that does not disable intx during
msi enabling like:
DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,
                        0x2e22,
                        quirk_msi_intx_disable_bug);

Thanks

Yinghai
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