Re: [PATCH v13 5/6] i2c: tegra: Add support for SW mutex register
From: Wolfram Sang
Date: Tue Jan 13 2026 - 10:42:36 EST
On Tue, Nov 18, 2025 at 07:36:19PM +0530, Akhil R wrote:
> From: Kartik Rajput <kkartik@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Signed-off-by: Akhil R <akhilrajeev@xxxxxxxxxx>
> Reviewed-by: Jon Hunter <jonathanh@xxxxxxxxxx>
> Acked-by: Thierry Reding <treding@xxxxxxxxxx>
Applied to for-next, thanks!
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