linux-kernel - Re: [PATCH v4 6/7] phy: exynos5-usbdrd: subscribe to orientation notifier if required

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Message-ID: <7c0dcf24-187c-4dc8-aa4a-4a8f814775b2@kernel.org>
Date: Sat, 15 Feb 2025 11:07:45 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Marek Szyprowski <m.szyprowski@...sung.com>,
 André Draszik <andre.draszik@...aro.org>,
 Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Sylwester Nawrocki <s.nawrocki@...sung.com>,
 Alim Akhtar <alim.akhtar@...sung.com>
Cc: Peter Griffin <peter.griffin@...aro.org>,
 Tudor Ambarus <tudor.ambarus@...aro.org>,
 Sam Protsenko <semen.protsenko@...aro.org>,
 Will McVicker <willmcvicker@...gle.com>, Roy Luo <royluo@...gle.com>,
 kernel-team@...roid.com, linux-phy@...ts.infradead.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v4 6/7] phy: exynos5-usbdrd: subscribe to orientation
 notifier if required

On 14/02/2025 20:30, Marek Szyprowski wrote:
> On 06.12.2024 17:31, André Draszik wrote:
>> gs101's SS phy needs to be configured differently based on the
>> connector orientation, as the SS link can only be established if the
>> mux is configured correctly.
>>
>> The code to handle programming of the mux is in place already, this commit
>> now adds the missing pieces to subscribe to the Type-C orientation
>> switch event.
>>
>> Note that for this all to work we rely on the USB controller
>> re-initialising us. It should invoke our .exit() upon cable unplug, and
>> during cable plug we'll receive the orientation event after which we
>> expect our .init() to be called.
>>
>> Above reinitialisation happens if the DWC3 controller can enter runtime
>> suspend automatically. For the DWC3 driver, this is an opt-in:
>>      echo auto > /sys/devices/.../11110000.usb/power/control
>> Once done, things work as long as the UDC is not bound as otherwise it
>> stays busy because it doesn't cancel / stop outstanding TRBs. For now
>> we have to manually unbind the UDC in that case:
>>       echo "" > sys/kernel/config/usb_gadget/.../UDC
>>
>> Note that if the orientation-switch property is missing from the DT,
>> the code will behave as before this commit (meaning for gs101 it will
>> work in SS mode in one orientation only). Other platforms are not
>> affected either way.
>>
>> Signed-off-by: André Draszik <andre.draszik@...aro.org>
>>
>> ---
>> v3:
>> * drop init to -1 of phy_drd->orientation (Vinod)
>> * avoid #ifdef and switch to normal conditional IS_ENABLED() for
>>    CONFIG_TYPEC
>>
>> v2:
>> * move #include typec_mux.h from parent patch into this one (Peter)
>> ---
>>   drivers/phy/samsung/Kconfig              |  1 +
>>   drivers/phy/samsung/phy-exynos5-usbdrd.c | 56 ++++++++++++++++++++++++++++++++
>>   2 files changed, 57 insertions(+)
>>
>> diff --git a/drivers/phy/samsung/Kconfig b/drivers/phy/samsung/Kconfig
>> index f10afa3d7ff5..fc7bd1088576 100644
>> --- a/drivers/phy/samsung/Kconfig
>> +++ b/drivers/phy/samsung/Kconfig
>> @@ -80,6 +80,7 @@ config PHY_EXYNOS5_USBDRD
>>   	tristate "Exynos5 SoC series USB DRD PHY driver"
>>   	depends on (ARCH_EXYNOS && OF) || COMPILE_TEST
>>   	depends on HAS_IOMEM
>> +	depends on TYPEC || (TYPEC=n && COMPILE_TEST)

BTW, this syntax never made any sense - it did not work. The optional
dependency is expressed as:
	depends on TYPEC || !TYPEC

but what it epxressed is that it is possible to build it without typec
only for compile test, which is odd if this was meant to be optional.
And further code:
	if (!IS_ENABLED(CONFIG_TYPEC))

clearly suggests this should be optional.


Best regards,
Krzysztof