linux-kernel - Re: [PATCH v13 5/6] i2c: tegra: Add support for SW mutex register

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Message-ID: <aWZn6boSNd0Z4F1b@ninjato>
Date: Tue, 13 Jan 2026 16:42:33 +0100
From: Wolfram Sang <wsa+renesas@...g-engineering.com>
To: Akhil R <akhilrajeev@...dia.com>
Cc: andi.shyti@...nel.org, digetx@...il.com, jonathanh@...dia.com,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-tegra@...r.kernel.org, thierry.reding@...il.com,
	wsa@...nel.org, kkartik@...dia.com, ldewangan@...dia.com,
	smangipudi@...dia.com
Subject: Re: [PATCH v13 5/6] i2c: tegra: Add support for SW mutex register

On Tue, Nov 18, 2025 at 07:36:19PM +0530, Akhil R wrote:
> From: Kartik Rajput <kkartik@...dia.com>
> 
> Add support for SW mutex register introduced in Tegra264 to provide
> an option to share the interface between multiple firmwares and/or
> VMs. This involves following steps:
> 
>  - A firmware/OS writes its unique ID to the mutex REQUEST field.
>  - Ownership is established when reading the GRANT field returns the
>    same ID.
>  - If GRANT shows a different non-zero ID, the firmware/OS retries
>    until timeout.
>  - After completing access, it releases the mutex by writing 0.
> 
> However, the hardware does not ensure any protection based on the
> values. The driver/firmware should honor the peer who already holds
> the mutex.
> 
> Signed-off-by: Kartik Rajput <kkartik@...dia.com>
> Signed-off-by: Akhil R <akhilrajeev@...dia.com>
> Reviewed-by: Jon Hunter <jonathanh@...dia.com>
> Acked-by: Thierry Reding <treding@...dia.com>

Applied to for-next, thanks!


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