Received-SPF: pass (google.com: domain of linux-kernel+bounces-185853-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
Message-ID: <92dcd555-69b1-4111-92dd-debe5107d526@kernel.org>
Date: Wed, 22 May 2024 09:26:00 +0200
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 5/7] dt-bindings: remoteproc: qcom,pas: Add hwlocks
To: Bjorn Andersson <quic_bjorande@quicinc.com>
Cc: Chris Lew <quic_clew@quicinc.com>, Bjorn Andersson
 <andersson@kernel.org>, Baolin Wang <baolin.wang@linux.alibaba.com>,
 Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
 Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
 Boqun Feng <boqun.feng@gmail.com>, Jonathan Corbet <corbet@lwn.net>,
 Mathieu Poirier <mathieu.poirier@linaro.org>, Rob Herring <robh@kernel.org>,
 Krzysztof Kozlowski <krzk+dt@kernel.org>, Conor Dooley
 <conor+dt@kernel.org>,
 Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
 Konrad Dybcio <konrad.dybcio@linaro.org>, linux-remoteproc@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
 linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org
References: <20240516-hwspinlock-bust-v1-0-47a90a859238@quicinc.com>
 <20240516-hwspinlock-bust-v1-5-47a90a859238@quicinc.com>
 <3521519f-34b8-472d-be37-f0e64bba24fc@kernel.org>
 <a944418a-1699-44fa-bdfc-2e57129adea1@quicinc.com>
 <c9882ba0-bbbf-44ec-9606-ebe68bcb8866@kernel.org>
 <ZkzzY311XiRigJPt@hu-bjorande-lv.qualcomm.com>
From: Krzysztof Kozlowski <krzk@kernel.org>
Content-Language: en-US
Autocrypt: addr=krzk@kernel.org; keydata=
 xsFNBFVDQq4BEAC6KeLOfFsAvFMBsrCrJ2bCalhPv5+KQF2PS2+iwZI8BpRZoV+Bd5kWvN79
 cFgcqTTuNHjAvxtUG8pQgGTHAObYs6xeYJtjUH0ZX6ndJ33FJYf5V3yXqqjcZ30FgHzJCFUu
 JMp7PSyMPzpUXfU12yfcRYVEMQrmplNZssmYhiTeVicuOOypWugZKVLGNm0IweVCaZ/DJDIH
 gNbpvVwjcKYrx85m9cBVEBUGaQP6AT7qlVCkrf50v8bofSIyVa2xmubbAwwFA1oxoOusjPIE
 J3iadrwpFvsZjF5uHAKS+7wHLoW9hVzOnLbX6ajk5Hf8Pb1m+VH/E8bPBNNYKkfTtypTDUCj
 NYcd27tjnXfG+SDs/EXNUAIRefCyvaRG7oRYF3Ec+2RgQDRnmmjCjoQNbFrJvJkFHlPeHaeS
 BosGY+XWKydnmsfY7SSnjAzLUGAFhLd/XDVpb1Een2XucPpKvt9ORF+48gy12FA5GduRLhQU
 vK4tU7ojoem/G23PcowM1CwPurC8sAVsQb9KmwTGh7rVz3ks3w/zfGBy3+WmLg++C2Wct6nM
 Pd8/6CBVjEWqD06/RjI2AnjIq5fSEH/BIfXXfC68nMp9BZoy3So4ZsbOlBmtAPvMYX6U8VwD
 TNeBxJu5Ex0Izf1NV9CzC3nNaFUYOY8KfN01X5SExAoVTr09ewARAQABzSVLcnp5c3p0b2Yg
 S296bG93c2tpIDxrcnprQGtlcm5lbC5vcmc+wsGVBBMBCgA/AhsDBgsJCAcDAgYVCAIJCgsE
 FgIDAQIeAQIXgBYhBJvQfg4MUfjVlne3VBuTQ307QWKbBQJgPO8PBQkUX63hAAoJEBuTQ307
 QWKbBn8P+QFxwl7pDsAKR1InemMAmuykCHl+XgC0LDqrsWhAH5TYeTVXGSyDsuZjHvj+FRP+
 gZaEIYSw2Yf0e91U9HXo3RYhEwSmxUQ4Fjhc9qAwGKVPQf6YuQ5yy6pzI8brcKmHHOGrB3tP
 /MODPt81M1zpograAC2WTDzkICfHKj8LpXp45PylD99J9q0Y+gb04CG5/wXs+1hJy/dz0tYy
 iua4nCuSRbxnSHKBS5vvjosWWjWQXsRKd+zzXp6kfRHHpzJkhRwF6ArXi4XnQ+REnoTfM5Fk
 VmVmSQ3yFKKePEzoIriT1b2sXO0g5QXOAvFqB65LZjXG9jGJoVG6ZJrUV1MVK8vamKoVbUEe
 0NlLl/tX96HLowHHoKhxEsbFzGzKiFLh7hyboTpy2whdonkDxpnv/H8wE9M3VW/fPgnL2nPe
 xaBLqyHxy9hA9JrZvxg3IQ61x7rtBWBUQPmEaK0azW+l3ysiNpBhISkZrsW3ZUdknWu87nh6
 eTB7mR7xBcVxnomxWwJI4B0wuMwCPdgbV6YDUKCuSgRMUEiVry10xd9KLypR9Vfyn1AhROrq
 AubRPVeJBf9zR5UW1trJNfwVt3XmbHX50HCcHdEdCKiT9O+FiEcahIaWh9lihvO0ci0TtVGZ
 MCEtaCE80Q3Ma9RdHYB3uVF930jwquplFLNF+IBCn5JRzsFNBFVDXDQBEADNkrQYSREUL4D3
 Gws46JEoZ9HEQOKtkrwjrzlw/tCmqVzERRPvz2Xg8n7+HRCrgqnodIYoUh5WsU84N03KlLue
 MNsWLJBvBaubYN4JuJIdRr4dS4oyF1/fQAQPHh8Thpiz0SAZFx6iWKB7Qrz3OrGCjTPcW6ei
 OMheesVS5hxietSmlin+SilmIAPZHx7n242u6kdHOh+/SyLImKn/dh9RzatVpUKbv34eP1wA
 GldWsRxbf3WP9pFNObSzI/Bo3kA89Xx2rO2roC+Gq4LeHvo7ptzcLcrqaHUAcZ3CgFG88CnA
 6z6lBZn0WyewEcPOPdcUB2Q7D/NiUY+HDiV99rAYPJztjeTrBSTnHeSBPb+qn5ZZGQwIdUW9
 YegxWKvXXHTwB5eMzo/RB6vffwqcnHDoe0q7VgzRRZJwpi6aMIXLfeWZ5Wrwaw2zldFuO4Dt
 91pFzBSOIpeMtfgb/Pfe/a1WJ/GgaIRIBE+NUqckM+3zJHGmVPqJP/h2Iwv6nw8U+7Yyl6gU
 BLHFTg2hYnLFJI4Xjg+AX1hHFVKmvl3VBHIsBv0oDcsQWXqY+NaFahT0lRPjYtrTa1v3tem/
 JoFzZ4B0p27K+qQCF2R96hVvuEyjzBmdq2esyE6zIqftdo4MOJho8uctOiWbwNNq2U9pPWmu
 4vXVFBYIGmpyNPYzRm0QPwARAQABwsF8BBgBCgAmAhsMFiEEm9B+DgxR+NWWd7dUG5NDfTtB
 YpsFAmA872oFCRRflLYACgkQG5NDfTtBYpvScw/9GrqBrVLuJoJ52qBBKUBDo4E+5fU1bjt0
 Gv0nh/hNJuecuRY6aemU6HOPNc2t8QHMSvwbSF+Vp9ZkOvrM36yUOufctoqON+wXrliEY0J4
 ksR89ZILRRAold9Mh0YDqEJc1HmuxYLJ7lnbLYH1oui8bLbMBM8S2Uo9RKqV2GROLi44enVt
 vdrDvo+CxKj2K+d4cleCNiz5qbTxPUW/cgkwG0lJc4I4sso7l4XMDKn95c7JtNsuzqKvhEVS
 oic5by3fbUnuI0cemeizF4QdtX2uQxrP7RwHFBd+YUia7zCcz0//rv6FZmAxWZGy5arNl6Vm
 lQqNo7/Poh8WWfRS+xegBxc6hBXahpyUKphAKYkah+m+I0QToCfnGKnPqyYIMDEHCS/RfqA5
 t8F+O56+oyLBAeWX7XcmyM6TGeVfb+OZVMJnZzK0s2VYAuI0Rl87FBFYgULdgqKV7R7WHzwD
 uZwJCLykjad45hsWcOGk3OcaAGQS6NDlfhM6O9aYNwGL6tGt/6BkRikNOs7VDEa4/HlbaSJo
 7FgndGw1kWmkeL6oQh7wBvYll2buKod4qYntmNKEicoHGU+x91Gcan8mCoqhJkbqrL7+nXG2
 5Q/GS5M9RFWS+nYyJh+c3OcfKqVcZQNANItt7+ULzdNJuhvTRRdC3g9hmCEuNSr+CLMdnRBY fv0=
In-Reply-To: <ZkzzY311XiRigJPt@hu-bjorande-lv.qualcomm.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit

On 21/05/2024 21:17, Bjorn Andersson wrote:
>>>
>>> Hi Krzysztof,
>>>
>>> Sorry for the confusion, I dont think I meant that the smem driver will 
>>> ever crash. The referred to crash in the cover letter is a crash in the 
>>> firmware running on the remoteproc. The remoteproc could crash for any 
>>> unexpected reason, related or unrelated to smem, while holding the tcsr 
>>> mutex. I want to ensure that all resources that a remoteproc might be 
>>> using are released as part of remoteproc stop.
>>>
>>> The SMEM driver manages the lock/unlock operations on the tcsr mutex 
>>> from the Linux CPU's perspective. This case is for cleaning up from the 
>>> remote side's perspective.
>>>
>>> In this case it's the hwspinlock used to synchronize SMEM, but it's 
>>> conceivable that firmware running on the remoteproc has additional locks 
>>> that need to be busted in order for the system to continue executing 
>>> until the firmware is reinitialized.
>>>
>>> We did consider tying this to the SMEM instance, but the entitiy 
>>> relating to firmware is the remoteproc instance.
>>
>> I still do not understand why you have to add hwlock to remoteproc, even
>> though it is not directly used. Your driver problem looks like lack of
>> proper driver architecture - you want to control the locks not from the
>> layer took the lock, but one layer up. Sorry, no, fix the driver
>> architecture.
>>
> 
> No, it is the firmware's reference to the lock that is represented in
> the remoteproc node, while SMEM deals with Linux's reference to the lock.
> 
> This reference would be used to release the lock - on behalf of the
> firmware - in the event that the firmware held it when it
> stopped/crashed.

I understood, but the remoteproc driver did not acquire the hardware
lock. It was taken by smem, if I got it correctly, so you should poke
smem to bust the spinlock.

The hwlock is not a property of remote proc, because remote proc does
not care, right? Other device cares... and now for every smem user you
will add new binding property?

No, you are adding a binding based on your driver solution.

Best regards,
Krzysztof