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Wed, 18 Mar 2026 23:32:26 -0700 (PDT) Received: from hu-batta-hyd.qualcomm.com ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b06e603937sm48572485ad.57.2026.03.18.23.32.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2026 23:32:25 -0700 (PDT) From: Kishore Batta Date: Thu, 19 Mar 2026 12:01:49 +0530 Subject: [PATCH v4 9/9] Documentation: ABI: Add sysfs ABI documentation for DDR training data Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260319-sahara_protocol_new_v2-v4-9-47ad79308762@oss.qualcomm.com> References: <20260319-sahara_protocol_new_v2-v4-0-47ad79308762@oss.qualcomm.com> In-Reply-To: <20260319-sahara_protocol_new_v2-v4-0-47ad79308762@oss.qualcomm.com> To: Jonathan Corbet , Shuah Khan , Jeff Hugo , Carl Vanderlip , Oded Gabbay , Manivannan Sadhasivam , andersson@kernel.org Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, mhi@lists.linux.dev, Kishore Batta X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; 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The documented sysfs node provides read-only access to the DDR training data captured during sahara command mode and exposed via the MHI controller device. This allows userspace to read the training data and manage it as needed outside the kernel. Signed-off-by: Kishore Batta --- .../ABI/testing/sysfs-bus-mhi-ddr_training_data | 19 +++++++++++++++= ++++ 1 file changed, 19 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-mhi-ddr_training_data b/Do= cumentation/ABI/testing/sysfs-bus-mhi-ddr_training_data new file mode 100644 index 0000000000000000000000000000000000000000..810b487b5a5fdba133d81255f98= 79844e3938a10 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-mhi-ddr_training_data @@ -0,0 +1,19 @@ +What: /sys/bus/mhi/devices//ddr_training_data + +Date: March 2026 + +Contact: Kishore Batta + +Description: Contains the DDR training data for the Qualcomm de= vice + connected. MHI driver populates different controll= er + nodes for each device. The DDR training data is ex= posed + to userspace to read and save the training data fi= le to + the filesystem. In the subsequent boot up of the d= evice, + the training data is restored from host to device + optimizing the boot up time of the device. + +Usage: Example for reading DDR training data: + cat /sys/bus/mhi/devices/mhi0/ddr_training_data + +Permissions: The file permissions are set to 0444 allowing read + access. --=20 2.34.1