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Mon, 16 Feb 2026 10:11:21 -0800 (PST) Received: from dianders.sjc.corp.google.com ([2a00:79e0:2e7c:8:2953:dae1:1e39:73b3]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-12742c64282sm13724326c88.5.2026.02.16.10.11.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Feb 2026 10:11:20 -0800 (PST) From: Douglas Anderson To: jassisinghbrar@gmail.com Cc: Douglas Anderson , Frank.Li@nxp.com, Santosh Shilimkar , Sascha Hauer , andersson@kernel.org, arm-scmi@vger.kernel.org, cristian.marussi@arm.com, daniel.baluta@nxp.com, festevam@gmail.com, imx@lists.linux.dev, jay.buddhabhatti@amd.com, jonathanh@nvidia.com, kernel@pengutronix.de, konradybcio@kernel.org, krzk@kernel.org, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-tegra@vger.kernel.org, lucaswei@google.com, marco.crivellari@suse.com, mathieu.poirier@linaro.org, michal.simek@amd.com, nm@ti.com, rafael@kernel.org, robh@kernel.org, shawn.guo@linaro.org, sudeep.holla@kernel.org, tglx@kernel.org, thierry.reding@gmail.com Subject: [PATCH v3 00/15] mailbox: Stop sending NULL mailbox messages Date: Mon, 16 Feb 2026 10:09:37 -0800 Message-ID: <20260216181002.3475421-1-dianders@chromium.org> X-Mailer: git-send-email 2.53.0.273.g2a3d683680-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit As talked about in the first patch in this series, passing NULL as the 'mssg' argument to mbox_send_message() ends up causing confusion and quirky behavior inside the mailbox core. Despite this, there are a number of drivers that pass NULL. It is plausible that some of the drivers passing NULL may have been taking advantage of the quirks of the mailbox core. Specifically, they may have been taking advantage that calling "tx_done" wasn't truly necessary for NULL messages (it was a noop) or that NULL messages were passed onto the mailbox controller right away without queuing. This series introduces a new API call: mbox_ring_doorbell(). The new API call tries to mimic the specific quirks that were helpful in the old behavior and it's expected to be a nearly drop-in replacement. There are some subtle differences between the new call and the old behavior, but it's expected that all of these differences are only for cases where the old behavior made little sense. The description of the first patch details these differences. The series attempts to convert all in-tree users to stop passing NULL for mssg. As per above, there are some slight differences in behavior. If any of the patches are causing problems, they can safely be reverted while debugging the problems. Eventually, all code should be converted over to stop passing NULL mssg. Changes in v3: - Suggest mbox_ring_doorbell in the warning message - Updated patch description based on Cristian's response. Changes in v2: - Instead of just documenting NULL, introduce a new function Douglas Anderson (15): mailbox: Deprecate NULL mbox messages; Introduce mbox_ring_doorbell() ACPI: PCC: Use mbox_ring_doorbell() instead of NULL message firmware: arm_scmi: Use mbox_ring_doorbell() instead of NULL message firmware: imx-dsp: Use mbox_ring_doorbell() instead of NULL message firmware: tegra: bpmp: Use mbox_ring_doorbell() instead of NULL message irqchip/qcom-mpm: Use mbox_ring_doorbell() instead of NULL message remoteproc: xlnx: Use mbox_ring_doorbell() instead of NULL message rpmsg: qcom_glink_rpm: Use mbox_ring_doorbell() instead of NULL message rpmsg: glink: smem: Use mbox_ring_doorbell() instead of NULL message rpmsg: qcom_smd: Use mbox_ring_doorbell() instead of NULL message soc: qcom: aoss: Use mbox_ring_doorbell() instead of NULL message soc: qcom: smp2p: Use mbox_ring_doorbell() instead of NULL message soc: qcom: smsm: Use mbox_ring_doorbell() instead of NULL message soc: ti: wkup_m3_ipc: Use mbox_ring_doorbell() instead of NULL message drivers: firmware: xilinx: Use mbox_ring_doorbell() instead of NULL message drivers/acpi/acpi_pcc.c | 4 +- .../firmware/arm_scmi/transports/mailbox.c | 8 +- drivers/firmware/imx/imx-dsp.c | 2 +- drivers/firmware/tegra/bpmp-tegra186.c | 4 +- drivers/irqchip/irq-qcom-mpm.c | 2 +- drivers/mailbox/mailbox.c | 82 ++++++++++++++++++- drivers/remoteproc/xlnx_r5_remoteproc.c | 2 +- drivers/rpmsg/qcom_glink_rpm.c | 3 +- drivers/rpmsg/qcom_glink_smem.c | 3 +- drivers/rpmsg/qcom_smd.c | 13 +-- drivers/soc/qcom/qcom_aoss.c | 3 +- drivers/soc/qcom/smp2p.c | 8 +- drivers/soc/qcom/smsm.c | 8 +- drivers/soc/ti/wkup_m3_ipc.c | 10 +-- drivers/soc/xilinx/zynqmp_power.c | 2 +- include/linux/mailbox_client.h | 1 + include/linux/mailbox_controller.h | 4 +- 17 files changed, 108 insertions(+), 51 deletions(-) -- 2.53.0.273.g2a3d683680-goog