[PATCH v2 1/2] usb: ohci-at91: Forcibly suspend ports while USB suspend

Le 03/06/2016 11:22, Yang, Wenyou a ?crit :

quoted

-----Original Message-----
From: Rob Herring [mailto:robh at kernel.org]
Sent: 2016?6?3? 9:54
To: Yang, Wenyou <redacted>
Cc: Alan Stern <stern@rowland.harvard.edu>; Greg Kroah-Hartman
[off-list ref]; Ferre, Nicolas [off-list ref];
Pawel Moll [off-list ref]; Mark Brown [off-list ref]; Ian
Campbell [off-list ref]; Kumar Gala [off-list ref];
Alexandre Belloni [off-list ref]; linux-
kernel at vger.kernel.org; devicetree at vger.kernel.org; linux-arm-
kernel at lists.infradead.org; linux-usb at vger.kernel.org
Subject: Re: [PATCH v2 1/2] usb: ohci-at91: Forcibly suspend ports while USB
suspend

On Wed, Jun 01, 2016 at 12:29:59PM +0800, Wenyou Yang wrote:

quoted

In order to the save power consumption, as a workaround, suspend
forcibly the USB PORTA/B/C via set the SUSPEND_A/B/C bits of OHCI
Interrupt Configuration Register in the SFRs while OHCI USB suspend.

This suspend operation must be done before the USB clock is disabled,
resume after the USB clock is enabled.

Signed-off-by: Wenyou Yang <redacted>
---

Changes in v2:
 - Add compatible to support forcibly suspend the ports.
 - Add soc/at91/at91_sfr.h to accommodate the defines.
 - Add error checking for .sfr_regmap.
 - Remove unnecessary regmap_read() statement.

 .../devicetree/bindings/usb/atmel-usb.txt          |  5 +-
 drivers/usb/host/ohci-at91.c                       | 80 +++++++++++++++++++++-
 include/soc/at91/at91_sfr.h                        | 29 ++++++++
 3 files changed, 111 insertions(+), 3 deletions(-)  create mode
100644 include/soc/at91/at91_sfr.h

diff --git a/Documentation/devicetree/bindings/usb/atmel-usb.txt

b/Documentation/devicetree/bindings/usb/atmel-usb.txt
index 5883b73..3e3e58a 100644

--- a/Documentation/devicetree/bindings/usb/atmel-usb.txt
+++ b/Documentation/devicetree/bindings/usb/atmel-usb.txt

@@ -3,8 +3,9 @@ Atmel SOC USB controllers  OHCI

 Required properties:
- - compatible: Should be "atmel,at91rm9200-ohci" for USB controllers
-   used in host mode.
+ - compatible: Should be one of the following
+	       "atmel,at91rm9200-ohci" for USB controllers used in host mode.
+	       "atmel,sama5d2-ohci" for SAMA5D2 which can force to suspend.

That may be why you need this now, but that is irrelevant to having a chip specific
compatible string.

Maybe a property is better.

It seems that it's not an issue to the binding that Rob is talking about
but the description that you used: "for SAMA5D2 which can force
suspend". Don't modify it to use a property for this: a compatible sting
makes a lot of sense.

So just listing the new compatible string is enough. If the "force
suspend" is not needed anymore in next product, we will come back to the
"atmel,at91rm9200-ohci" compatible string or add a new one if needed...

bye,
-- 
Nicolas Ferre