Hi, Krzysztof.

-----Original Message-----
From: Krzysztof Kozlowski <krzk@kernel.org>
Sent: Monday, September 1, 2025 7:44 PM
To: Nas Chung <nas.chung@chipsnmedia.com>; mchehab@kernel.org;
hverkuil@xs4all.nl; robh@kernel.org; krzk+dt@kernel.org;
conor+dt@kernel.org; shawnguo@kernel.org; s.hauer@pengutronix.de
Cc: linux-media@vger.kernel.org; devicetree@vger.kernel.org; linux-
kernel@vger.kernel.org; linux-imx@nxp.com; linux-arm-
kernel@lists.infradead.org; jackson.lee [off-list ref];
lafley.kim [off-list ref]; Ming Qian [off-list ref]
Subject: Re: [PATCH v3 8/9] media: chips-media: wave6: Add Wave6 control
driver

On 01/09/2025 10:13, Nas Chung wrote:

quoted

Hi, Krzysztof.

Thanks for the feedback.

quoted

-----Original Message-----
From: Krzysztof Kozlowski <krzk@kernel.org>
Sent: Friday, August 29, 2025 11:06 PM
To: Nas Chung <nas.chung@chipsnmedia.com>; mchehab@kernel.org;
hverkuil@xs4all.nl; robh@kernel.org; krzk+dt@kernel.org;
conor+dt@kernel.org; shawnguo@kernel.org; s.hauer@pengutronix.de
Cc: linux-media@vger.kernel.org; devicetree@vger.kernel.org; linux-
kernel@vger.kernel.org; linux-imx@nxp.com; linux-arm-
kernel@lists.infradead.org; jackson.lee [off-list ref];
lafley.kim [off-list ref]; Ming Qian

[off-list ref]

quoted

quoted

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

On 29/08/2025 10:46, Nas Chung wrote:

quoted

+
+static void wave6_vpu_load_firmware(const struct firmware *fw, void

*context)

quoted

+{
+	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().

quoted

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()?

The callback checks the fw_available flag and returns immediately if false.
This flag is cleared in the remove() path under the lock.

Thanks,
Nas.

Best regards,
Krzysztof