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Tue, 11 Feb 2025 09:01:52 -0800 (PST) Received: from [10.67.48.245] ([192.19.223.252]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-2b82626f8b6sm3642741fac.38.2025.02.11.09.01.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 11 Feb 2025 09:01:51 -0800 (PST) Message-ID: Date: Tue, 11 Feb 2025 09:01:49 -0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 0/3] mmc: sdhci-brcmstb: Add rpmb sharing support To: Avri Altman , Ulf Hansson , Kamal Dasu , Jens Wiklander Cc: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "adrian.hunter@intel.com" , "linux-mmc@vger.kernel.org" , "robh@kernel.org" , "krzk+dt@kernel.org" , "conor+dt@kernel.org" , "wsa+renesas@sang-engineering.com" , "f.fainelli@gmail.com" , "bcm-kernel-feedback-list@broadcom.com" References: <20250206220940.10553-1-kamal.dasu@broadcom.com> <115a59e1-75b2-4d09-bbf9-50dfcd2b62dd@broadcom.com> Content-Language: en-US From: Florian Fainelli Autocrypt: addr=florian.fainelli@broadcom.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250211_090154_543364_D1A60BE2 X-CRM114-Status: GOOD ( 12.67 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2/11/25 00:13, Avri Altman wrote: >>>> This patch set adds support for Broadcom TZOS to read and write to >>>> RPMB partition using synchronized access to the controller hardware. > Practically it establishes a communication channel between the trust zone and the host controller regardless of the rpmb protocol. > Or did I get it wrong? Rather than communication channel, I would describe it as an arbitration scheme between N participants, with guaranteed forward progress and fairness between all participants. The interest here is for one of those participants to own the eMMC controller for a certain amount of time and indicate when it is done with it. This is not specific to eMMC as this could scale to virtually any piece of HW that is driven by transactions from a CPU, but the main application is for allowing the Trusted OS to own the eMMC controller for a short period of time in order to do its RPMB access, and then give it back in the same state it found it to the next participant. -- Florian