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{ "id": 2229273, "url": "http://patchwork.ozlabs.org/api/1.1/covers/2229273/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-i2c/cover/20260427-i2c-xiic-v1-0-e6207f9aa5ad@nexthop.ai/", "project": { "id": 35, "url": "http://patchwork.ozlabs.org/api/1.1/projects/35/?format=api", "name": "Linux I2C development", "link_name": "linux-i2c", "list_id": "linux-i2c.vger.kernel.org", "list_email": "linux-i2c@vger.kernel.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20260427-i2c-xiic-v1-0-e6207f9aa5ad@nexthop.ai>", "date": "2026-04-28T00:18:05", "name": "[0/3] i2c: xiic: fix SMBus block read and PEC support", "submitter": { "id": 92480, "url": "http://patchwork.ozlabs.org/api/1.1/people/92480/?format=api", "name": "Abdurrahman Hussain via B4 Relay", "email": "devnull+abdurrahman.nexthop.ai@kernel.org" }, "mbox": "http://patchwork.ozlabs.org/project/linux-i2c/cover/20260427-i2c-xiic-v1-0-e6207f9aa5ad@nexthop.ai/mbox/", "series": [ { "id": 501748, "url": "http://patchwork.ozlabs.org/api/1.1/series/501748/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-i2c/list/?series=501748", "date": "2026-04-28T00:18:06", "name": "i2c: xiic: fix SMBus block read and PEC support", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/501748/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2229273/comments/", "headers": { "Return-Path": "\n <linux-i2c+bounces-17190-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-i2c@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=Ou9HWgAW;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; 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a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1777335490; cv=none;\n b=Q4CWJASBFjMrprK4N7xSKJ4TMhtekMt45vVdHGjvS6cq1Z7MafYBYH96C0DHpDEzzWlGM4MZASl/szyin0BOYdVnyNf1R3aiiaGPe59pTsUjG7H7ijAx8bQQDkKtzc0zbOh0IpzPKOZ7ESnCCAx4R0UzuXQ/HXt9UFmYhlzAlQs=", "ARC-Message-Signature": "i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1777335490; c=relaxed/simple;\n\tbh=CsiHZ5vb7Sf7aVyvtEGZ7+CNeUx8W/SFG7JbsXLjEQE=;\n\th=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc;\n b=BQ32AdrzY3WQfSHC3EvMvyJPF63o5M08ujPPIe2hJ20R3bEXlF7pjXfvbcfSVHndrUlIOSL8Y/0coAAp2maZuPw6hCL7oMibAtnz2j7Iq0XlJrYs4F/ffvVi2L2alWjMAk37lDx9UpZ/znU5XnDbGDd1ZD0cp5fHTkdkgzxxK8c=", "ARC-Authentication-Results": "i=1; smtp.subspace.kernel.org;\n dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=Ou9HWgAW; arc=none smtp.client-ip=10.30.226.201", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n\ts=k20201202; t=1777335490;\n\tbh=CsiHZ5vb7Sf7aVyvtEGZ7+CNeUx8W/SFG7JbsXLjEQE=;\n\th=From:Subject:Date:To:Cc:Reply-To:From;\n\tb=Ou9HWgAWpBeePErzoQtCce8S3PWmyMP2WhR/V0s0A9Bod3jf+PusGVYD18z0QfjlN\n\t 6UD5FuWmiylBa4vWydKoWnn/Xf0ZsJCjqsfDKPqLERYppyfBpPF2/r7m7bJ8kh5P2Y\n\t Ojligkc0ohRUwKmvLgVgW8SbJbNzeZ0NSqDsUSA+/avOqr8hovXDpglsOP+KJJTkIG\n\t B65esENZh7ozi9GZ+kOi4FMfmZqge7b4en7vO+qJgjBffKeo6joPP+zqwD9LgR1wcV\n\t Pqkg7kjjS2t3fkNncxrIk+cS8SGcljGuxfLyc46HYw9hCyn7mIw1e0wZA8AwBcOiRB\n\t hNOW+bqH/k6dQ==", "From": "Abdurrahman Hussain via B4 Relay\n <devnull+abdurrahman.nexthop.ai@kernel.org>", "Subject": "[PATCH 0/3] i2c: xiic: fix SMBus block read and PEC support", "Date": "Mon, 27 Apr 2026 17:18:05 -0700", "Message-Id": "<20260427-i2c-xiic-v1-0-e6207f9aa5ad@nexthop.ai>", "Precedence": "bulk", "X-Mailing-List": "linux-i2c@vger.kernel.org", "List-Id": "<linux-i2c.vger.kernel.org>", "List-Subscribe": "<mailto:linux-i2c+subscribe@vger.kernel.org>", "List-Unsubscribe": "<mailto:linux-i2c+unsubscribe@vger.kernel.org>", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=\"utf-8\"", "Content-Transfer-Encoding": "7bit", "X-B4-Tracking": "v=1; b=H4sIAL3872kC/yXMSwqAMAxF0a1IxhZq8ANuRRzUGDUOqrQqQuner\n To8cN8L4NkJe2izAI4v8bLZhCLPgBZjZ1YyJgNqrHWJjRIkdYuQQsNDpQsmjQZSvjue5P6uuv6\n 3P4eV6Xj3EOMD+w3U4mwAAAA=", "X-Change-ID": "20260427-i2c-xiic-2aeb501ec02a", "To": "Michal Simek <michal.simek@amd.com>, Andi Shyti <andi.shyti@kernel.org>", "Cc": "linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org,\n linux-kernel@vger.kernel.org, Abdurrahman Hussain <abdurrahman@nexthop.ai>", "X-Mailer": "b4 0.15.1", "X-Developer-Signature": "v=1; a=openpgp-sha256; l=2226;\n i=abdurrahman@nexthop.ai; h=from:subject:message-id;\n bh=CsiHZ5vb7Sf7aVyvtEGZ7+CNeUx8W/SFG7JbsXLjEQE=;\n b=owJ4nJvAy8zAJbYltPXv6rsCXxhPqyUxZL7/c1CCcemG8lNB+zimTlrSqKJ59d31H1dZVm4w5\n 98clSr9LMigo5SFQYyLQVZMkWXOI/83bR1tERtiDtnDzGFlAhnCwMUpABOZspaRYfvjn5c6/q7r\n K/zJrHWW7Wi07ZYaD+d7W91UKkJ+MvtfMWBkuPRz4joViehXlfpOOT+yFizSF1rYPEfR2m31H6k\n rynYrmQAl5VAE", "X-Developer-Key": "i=abdurrahman@nexthop.ai; a=openpgp;\n fpr=9CE24FEC86888658B05CC23FB45585FDABDD10F4", "X-Endpoint-Received": "by B4 Relay for abdurrahman@nexthop.ai/default with\n auth_id=756", "X-Original-From": "Abdurrahman Hussain <abdurrahman@nexthop.ai>", "Reply-To": "abdurrahman@nexthop.ai" }, "content": "This series fixes three independent bugs in the Xilinx AXI IIC driver\nthat together make SMBus block reads with PEC return -EBADMSG or -EIO\non otherwise clean transfers. They only surface when the client has\nI2C_CLIENT_PEC set; non-PEC block reads happen to mask each issue in\nturn.\n\nThe problems were uncovered driving an adm1266 PMBus device behind a\nXilinx AXI IIC FPGA block and reading its 64-byte blackbox record.\n\nPatch 1 stops xiic_smbus_block_read_setup() from truncating rx_msg->len.\nThe i2c core appends a byte to msg->len when PEC is enabled, so\noverwriting the length to \"block size + 1\" silently drops the PEC byte\nand i2c_smbus_check_pec() then reads the last payload byte as the PEC.\n\nPatch 2 raises the RX_FULL threshold so the interrupt only fires once\nevery remaining byte (payload plus optional PEC) is already buffered in\nthe FIFO. The previous threshold of rxmsg_len - 2 caused the\nbytes_rem == 1 path in xiic_read_rx() to NACK a byte still on the wire.\n\nPatch 3 stops the BNB handler from forcing tx_msg->len = 1 to signal\ncompletion. tx_msg and rx_msg alias the same i2c_msg during a receive,\nso this also clobbered rx_msg->len; and because tx_pos is already at 2\nin the PEC case, the unsigned subtraction in xiic_tx_space() underflowed\nand the STATE_DONE check fell through to STATE_ERROR. Advancing tx_pos\nup to msg->len drives tx_space to zero without touching the length.\n\nAll three patches are pure bug fixes; non-PEC behaviour is unchanged.\nTested on real hardware -- a Xilinx AXI IIC controller talking to an\nadm1266, where 64-byte PEC-checked block reads now complete cleanly.\n\nSigned-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>\n---\nAbdurrahman Hussain (3):\n i2c: xiic: preserve PEC byte length in SMBus block read setup\n i2c: xiic: defer RX_FULL until all trailing bytes are in FIFO\n i2c: xiic: don't clobber msg->len to signal block-read completion\n\n drivers/i2c/busses/i2c-xiic.c | 20 +++++++++++---------\n 1 file changed, 11 insertions(+), 9 deletions(-)\n---\nbase-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731\nchange-id: 20260427-i2c-xiic-2aeb501ec02a\n\nBest regards,\n-- \nAbdurrahman Hussain <abdurrahman@nexthop.ai>" }