linux-kernel - Re: [PATCH 0/2] i2c: i801: Force no IRQ for Dell Latitude E7450

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Message-ID: <20230523200350.62ab4788@endymion.delvare>
Date:   Tue, 23 May 2023 20:03:50 +0200
From:   Jean Delvare <jdelvare@...e.de>
To:     Marius Hoch <mail@...iushoch.de>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] i2c: i801: Force no IRQ for Dell Latitude E7450

Hi Marius,

On Sun, 14 May 2023 12:36:32 +0200, Marius Hoch wrote:
> The Dell Latitude E7450 uses IRQ 18 for the accelerometer,
> but also claims that the SMBus uses IRQ 18. This will
> result in:
> 
> i801_smbus 0000:00:1f.3: PCI INT C: failed to register GSI
> i801_smbus 0000:00:1f.3: Failed to enable SMBus PCI device (-16)
> i801_smbus: probe of 0000:00:1f.3 failed with error -16

The i2c-i801 driver supports shared IRQ. If this fails, this means that
the other driver is not passing IRQF_SHARED when registering the
interrupt. Which driver is this? I'd rather check whether sharing the
IRQ is possible, rather that falling back to polling, which has a
performance cost.

> Force the SMBus IRQ to IRQ_NOTCONNECTED in this case, so that
> we fall back to polling, which also seems to be what the (very
> dated) Windows 7 drivers on the Dell Latitude E7450 do.

What makes you think so?

-- 
Jean Delvare
SUSE L3 Support