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Date:   Fri, 19 Jan 2018 15:45:12 +0100
From:   Maxime Ripard <maxime.ripard@free-electrons.com>
To:     Chen-Yu Tsai <wens@csie.org>
Cc:     Kishon Vijay Abraham I <kishon@ti.com>,
        Hans de Goede <hdegoede@redhat.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-sunxi@googlegroups.com, stable@vger.kernel.org
Subject: Re: [PATCH] phy: allwinner: sun4i-usb: poll vbus changes on A23/A33
 when driving VBUS
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References: <20180119092541.7508-1-wens@csie.org>
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On Fri, Jan 19, 2018 at 05:25:41PM +0800, Chen-Yu Tsai wrote:
> The AXP223 PMIC, like the AXP221, does not generate VBUS change
> interrupts when N_VBUSEN is used to drive VBUS for the OTG port
> on the board.
>=20
> This was not noticed until recently, as most A23/A33 boards use
> a GPIO pin that does not support interrupts for OTG ID detection.
> This forces the driver to use polling. However the A33-OlinuXino
> uses a pin that does support interrupts, so the driver uses them.
> However the VBUS interrupt never fires, and the driver never gets
> to update the VBUS status. This results in musb timing out waiting
> for VBUS to rise.
>=20
> This was worked around for the AXP221 by resorting to polling
> changes in commit 91d96f06a760 ("phy-sun4i-usb: Add workaround for
> missing Vbus det interrupts on A31"). This patch adds the A23 and
> A33 to the list of SoCs that need the workaround.
>=20
> Fixes: fc1f45ed3043 ("phy-sun4i-usb: Add support for the usb-phys on the
> 		      sun8i-a33 SoC")
> Fixes: 123dfdbcfaf5 ("phy-sun4i-usb: Add support for the usb-phys on the
> 		      sun8i-a23 SoC")
> Cc: <stable@vger.kernel.org> # 4.3.x: 68dbc2ce77bb phy-sun4i-usb:
> 		Use of_match_node to get model specific config data
> Cc: <stable@vger.kernel.org> # 4.3.x: 5cf700ac9d50 phy: phy-sun4i-usb:
> 		Fix optional gpios failing probe
> Cc: <stable@vger.kernel.org> # 4.3.x: 04e59a0211ff phy-sun4i-usb:
> 		Fix irq free conditions to match request conditions
> Cc: <stable@vger.kernel.org> # 4.3.x: 91d96f06a760 phy-sun4i-usb:
> 		Add workaround for missing Vbus det interrupts on A31
> Cc: <stable@vger.kernel.org> # 4.3.x
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> ---
>=20
> This list might get longer if the newer AXP8xx PMICs also have this
> behavior. We could switch to a boolean in the per-compatible data,
> or just always use polling. The yet-merged R40 support will have this
> issue as well, as the R40 is paired with the AXP221. But for now,
> I'd like to have something that is easier to backport to stable, so
> we can at least fix this for the A23 and A33.
>=20
> Also, checkpatch.pl doesn't like the stable kernel prerequisite lines.

Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>

Maxime

--=20
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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