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Message-ID: <2e17654d-e2f5-480f-aca1-5ece8bc028e7@linaro.org>
Date: Thu, 4 Jan 2024 17:11:38 +0100
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Subject: Re: [PATCH 2/4] reset: add GPIO-based reset controller
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To: Sean Anderson <sean.anderson@seco.com>,
 Bjorn Andersson <andersson@kernel.org>,
 Konrad Dybcio <konrad.dybcio@linaro.org>,
 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
 Banajit Goswami <bgoswami@quicinc.com>, Liam Girdwood <lgirdwood@gmail.com>,
 Mark Brown <broonie@kernel.org>, Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Philipp Zabel <p.zabel@pengutronix.de>,
 Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>,
 linux-arm-msm@vger.kernel.org, alsa-devel@alsa-project.org,
 linux-sound@vger.kernel.org, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org
Cc: Bartosz Golaszewski <brgl@bgdev.pl>
References: <20231222150133.732662-1-krzysztof.kozlowski@linaro.org>
 <20231222150133.732662-3-krzysztof.kozlowski@linaro.org>
 <530e3473-eb3b-477c-8599-e7aa12779640@seco.com>
 <88bd6668-7e67-42c7-97b6-d7029f371349@linaro.org>
 <075990bb-5fdb-4d30-9484-9df6b978e805@seco.com>
From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
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In-Reply-To: <075990bb-5fdb-4d30-9484-9df6b978e805@seco.com>
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On 04/01/2024 17:04, Sean Anderson wrote:
> 
>>> Maybe we take the max? But the driver below seems
>>> to only have access to one device. Which I suppose begs the question: how do
>>> we know when it's safe to deassert the reset (e.g. we've gotten to the point
>>> where all devices using this reset gpio have gotten far enough to detect that
>>> they use it)?
>>
>> The driver (reset consumer) knows when it is safe or not. You must
>> implement proper reset handling in your driver.
> 
> The driver has no idea whether it is safe or not. It just calls
> reset_assert/deassert at the appropriate time, and the reset
> framework/controller is supposed to coordinate things so e.g. the device
> doesn't get reset multiple times as multiple drivers all probe.

Hm, wait, now maybe I understand your concern. Did you read the
patchset? This is for the coordinated, shared, non-exclusive reset by
design.  And as stated during previous discussions: that's the driver's
job to be sure it is called like that.

Best regards,
Krzysztof