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[212.71.14.70]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4ba0233e5d7sm58289665e9.1.2026.11.10.08.48.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2026 08:48:04 -0800 (PST) From: Sander Speetjens Date: Tue, 10 Nov 2026 17:47:50 +0100 Subject: [PATCH v3 4/5] firmware: raspberrypi: Document memory barriers in property list path X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261110-fix-raspberrypi-firmware-v3-4-e001feb542dd@gmail.com> References: <20261110-fix-raspberrypi-firmware-v3-0-e001feb542dd@gmail.com> In-Reply-To: <20261110-fix-raspberrypi-firmware-v3-0-e001feb542dd@gmail.com> To: Florian Fainelli , Broadcom internal kernel review list , Eric Anholt , Stefan Wahren , Stephen Boyd , Nicolas Saenz Julienne Cc: linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, sander.speetjens@gmail.com, Manuel Ebner X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=1089; i=sander.speetjens@gmail.com; h=from:subject:message-id; bh=u/0CXjUNJhX1Rd5kE+A4P6p5kJKiKCpC4dI5cLjLhDQ=; b=owEBbQKS/ZANAwAKAXjNeEUMBchnAcsmYgBq80rA5oweI1D8pEFyiEAbgaJgSX6prZmEY9bqT Jj1+VYvTtCJAjMEAAEKAB0WIQRWUkqLABoRw+7JUQF4zXhFDAXIZwUCavNKwAAKCRB4zXhFDAXI Z5qFD/9snD3hL7PG1O7mpkf5M7Iw6hLyt6XYWllAf7G+6Yux6pLRVPnMwifq0GyoWl4JGCxI2Ra MatpWsIwzW64Kg2ZrtxDPQgUpmEz593N6XbUCZJyRdG8GKVWYHAdT5Xgb02zGJ/PAvyVxPuLZCm BeLi0SNzqH6/Rpg2FQBtR2VoPkSOx91ijpLngvFRMXDQKNxvwkGcgm9SqQaUHa9ozCaE10PWx9e 7/qiD3SVPLbMXOQt6xNbp97QoKZ8Q6Pr74JIG246pRFAUfOxKB7mqGZbhi8IdhLQbQT60SAZg7y uQDhWedQMeUhcZqrZfiIHtupekcsuv7+rGWylMO/D/F4mv1hHZgBHf2r1hYr4uSNQiQVUZCpKAX b/N1P1sGiGkxggws1qDV24srGjfT3/o344MTKIFx9hkm2wvwgerJQFG6miNinZFjPS4/GZupD3S YJBCpvLPzZ6JgnmItPAmuK1t6Q78B5rxfIvddhh62jCYRN+TJAWsPQsIt5v0GMYv4Ac6RGQ6o5V XS+2cuuKv8Sxwd6QZw6mejnAKwzaPaCXlovUIZgP3Hz6tMMZeFp3T3dLjNqR/JlSF/ertZvNu2M GSlHZZRajR0SFiMkPkrV80ZTRBp9Svaphle/A8gAIAbJZ88cLtJOCJtfYpoWSuKmiZQ9avAqClU djHiFh09WZgfmFA== X-Developer-Key: i=sander.speetjens@gmail.com; a=openpgp; fpr=56524A8B001A11C3EEC9510178CD78450C05C867 Add comments explaining the wmb() before the firmware transaction and the rmb() before reading the response, as required by coding style. Reviewed-by: Manuel Ebner Signed-off-by: Sander Speetjens --- drivers/firmware/raspberrypi.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c index 04163c3f385d..ef3326d5cf30 100644 --- a/drivers/firmware/raspberrypi.c +++ b/drivers/firmware/raspberrypi.c @@ -111,10 +111,12 @@ int rpi_firmware_property_list(struct rpi_firmware *fw, buf[1] = RPI_FIRMWARE_STATUS_REQUEST; memcpy(&buf[2], data, tag_size); buf[size / 4 - 1] = RPI_FIRMWARE_PROPERTY_END; + /* Make sure the writes to the buffer are visible to the firmware. */ wmb(); ret = rpi_firmware_transaction(fw, MBOX_CHAN_PROPERTY, bus_addr); + /* Make sure we see the firmware's response before reading it. */ rmb(); memcpy(data, &buf[2], tag_size); if (ret == 0 && buf[1] != RPI_FIRMWARE_STATUS_SUCCESS) { -- 2.56.0