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Subject: Re: [PATCH] phy: allwinner: sun4i-usb: poll vbus changes on A23/A33
 when driving VBUS
To:     Maxime Ripard <maxime.ripard@free-electrons.com>,
        Chen-Yu Tsai <wens@csie.org>
References: <20180119092541.7508-1-wens@csie.org>
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CC:     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>
From:   Kishon Vijay Abraham I <kishon@ti.com>
Message-ID: <a38e269f-abe9-0560-1542-c115c5a64605@ti.com>
Date:   Fri, 16 Feb 2018 16:50:42 +0530
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On Friday 19 January 2018 08:15 PM, Maxime Ripard wrote:
> 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.
>>
>> 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.
>>
>> 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.
>>
>> 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>
>> ---
>>
>> 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.
>>
>> Also, checkpatch.pl doesn't like the stable kernel prerequisite lines.
> 
> Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>

merged, thanks!

-Kishon