linux-kernel - Re: [PATCH v3 8/9] media: chips-media: wave6: Add Wave6 control driver

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Message-ID: <4c8041ae-3b20-4c17-b9c2-0816f087717e@kernel.org>
Date: Mon, 1 Sep 2025 12:44:11 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Nas Chung <nas.chung@...psnmedia.com>,
 "mchehab@...nel.org" <mchehab@...nel.org>,
 "hverkuil@...all.nl" <hverkuil@...all.nl>, "robh@...nel.org"
 <robh@...nel.org>, "krzk+dt@...nel.org" <krzk+dt@...nel.org>,
 "conor+dt@...nel.org" <conor+dt@...nel.org>,
 "shawnguo@...nel.org" <shawnguo@...nel.org>,
 "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>
Cc: "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
 "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-imx@....com" <linux-imx@....com>,
 "linux-arm-kernel@...ts.infradead.org"
 <linux-arm-kernel@...ts.infradead.org>,
 "jackson.lee" <jackson.lee@...psnmedia.com>,
 "lafley.kim" <lafley.kim@...psnmedia.com>, Ming Qian <ming.qian@....nxp.com>
Subject: Re: [PATCH v3 8/9] media: chips-media: wave6: Add Wave6 control
 driver

On 01/09/2025 10:13, Nas Chung wrote:
> Hi, Krzysztof.
> 
> Thanks for the feedback.
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzk@...nel.org>
>> Sent: Friday, August 29, 2025 11:06 PM
>> To: Nas Chung <nas.chung@...psnmedia.com>; mchehab@...nel.org;
>> hverkuil@...all.nl; robh@...nel.org; krzk+dt@...nel.org;
>> conor+dt@...nel.org; shawnguo@...nel.org; s.hauer@...gutronix.de
>> Cc: linux-media@...r.kernel.org; devicetree@...r.kernel.org; linux-
>> kernel@...r.kernel.org; linux-imx@....com; linux-arm-
>> kernel@...ts.infradead.org; jackson.lee <jackson.lee@...psnmedia.com>;
>> lafley.kim <lafley.kim@...psnmedia.com>; Ming Qian <ming.qian@....nxp.com>
>> Subject: Re: [PATCH v3 8/9] media: chips-media: wave6: Add Wave6 control
>> driver
>>
>> On 29/08/2025 10:46, Nas Chung wrote:
>>> +
>>> +static void wave6_vpu_load_firmware(const struct firmware *fw, void
>> *context)
>>> +{
>>> +	struct wave6_vpu_device *vpu = context;
>>> +
>>> +	guard(mutex)(&vpu->lock);
>>
>> Why? How could this be called in parallel, before the probe?
> 
> This callback is called asynchronously via firmware_request_nowait_nowarn().
> In practice, I observed a case where the callback was executing
> while the device's release() function was being called.

Indeed. Now I wonder how does it protect from concurrent remove()?

Best regards,
Krzysztof