Re: [PATCH v3] HID: i2c-hid: Fix suspend/resume when already runtime suspended

From: Benson Leung
Date: Tue Mar 08 2016 - 18:13:14 EST

On Tue, Mar 8, 2016 at 3:03 PM, Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx> wrote:
> On ACPI-based systems ACPI power domain code runtime resumes device before
> calling suspend method, which ensures that i2c-hid suspend code starts with
> device not in low-power state and with interrupts enabled.
> On other systems, especially if device is not a part of any power domain,
> we may end up calling driver's system-level suspend routine while the
> device is runtime-suspended (with controller in presumably low power state
> and interrupts disabled). This will result in interrupts being essentially
> disabled twice, and we will only re-enable them after both system resume
> and runtime resume methods complete. Unfortunately i2c_hid_resume() calls
> i2c_hid_hwreset() and that only works properly if interrupts are enabled.
> Also if device is runtime-suspended driver's suspend code may fail if it
> tries to issue I/O requests.
> Let's fix it by runtime-resuming the device if we need to run HID driver's
> suspend code and also disabling interrupts only if device is not already
> runtime-suspended. Also on resume we mark the device as running at full
> power (since that is what resetting will do to it).
> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
> Signed-off-by: Dmitry Torokhov <dtor@xxxxxxxxxxxx>

Reviewed-by: Benson Leung <bleung@xxxxxxxxxxxx>

> ---
> This is an uprev of a patch that Doug sent a year ago (see
>, adjusted to the latest
> mainline. The change from v2 is that we runtime-resume the device before
> calling into HID driver's suspend callback.

Benson Leung
Senior Software Engineer, Chrom* OS