From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E2D36434E3A for ; Mon, 20 Jul 2026 15:06:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784560006; cv=none; b=bUTZkwXKgcAwQvzK9kxbrPGcuDtwh/NvJv8STi1wpNOwI4oFRTz2ZlW2z9M6iDrhitO0EcPav8b+nhn+3mcHw69OCFuRHVRxzinpUpE0vD49XR8la9Y6pEyoqSRebaMeM+JP1uOn3njiTQCQGwMwWg9itc4Lez9XOV9uhSmP2lw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784560006; c=relaxed/simple; bh=VOdtrrxtztPq+lgevxYDT5gmaP73dKb7nG80Nk/gZS4=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=q2rFE6e11RB8wfeWy7xse5DhJXjiovJ3Gqw6VAeenrzo5eP4rIODIpD1TNNn9jwG/HXRL6ihzp8Y847842US4jYdaxxrZ+O1GbM8wt1ENwTEcVm8U6gheyaTAc+/En/k1E774vYySs51jA5E/BsHh75eAA53E5ESyYlsgDVIsqs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=OqBqun0n; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="OqBqun0n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F19261F00A3A; Mon, 20 Jul 2026 15:06:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784560004; bh=v1Ua6jYxNsckwPXnHqMuUS8P8aZr8zy6Wf652YUna3o=; h=Subject:To:Cc:From:Date; b=OqBqun0n76xdhYxdNafWOthPiKVXTGquCD89KV2gQREJjjEtDRY8jvThZb/xqiQDq cTt8tkzciA1biH5IQ3mougnz6N/oeo4q/KRLyZR311TK1pOkkruYGe6XKLVqpR/H2F nbQaaTbYw/fGO960Edn1NNhY6BLUgAQi30hbxWYU= Subject: FAILED: patch "[PATCH] i2c: imx: fix locked bus on SMBus block-read of 0 (atomic)" failed to apply to 6.12-stable tree To: vjardin@free.fr,andi.shyti@kernel.org,carlos.song@nxp.com,eichest@gmail.com,o.rempel@pengutronix.de,stable@vger.kernel.org Cc: From: Date: Mon, 20 Jul 2026 17:06:35 +0200 Message-ID: <2026072035-flight-slacker-b884@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x cb2fc37857693b55909fb77dc2c87cfbc1cdc476 # git commit -s git send-email --to '' --in-reply-to '2026072035-flight-slacker-b884@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From cb2fc37857693b55909fb77dc2c87cfbc1cdc476 Mon Sep 17 00:00:00 2001 From: Vincent Jardin Date: Mon, 13 Jul 2026 20:11:59 +0200 Subject: [PATCH] i2c: imx: fix locked bus on SMBus block-read of 0 (atomic) SMBus 3.1 6.5.7 allows a Block Read byte count of 0, but the atomic (polling) path rejects it as -EPROTO. Worse, it returns without a NACK+STOP: the next receive cycle has already started, so the target keeps holding SDA and the bus stays stuck until a power cycle for this i2c controller. Reading I2DR to obtain the count likewise arms the next byte on the count > I2C_SMBUS_BLOCK_MAX path, which also returned -EPROTO directly and left the bus held. Handle both: NACK the in-flight dummy byte (TXAK) and extend msgs->len so the existing last-byte handling emits STOP; the dummy byte is discarded. A count of 0 is a valid empty block read; a count above I2C_SMBUS_BLOCK_MAX is still reported as -EPROTO, but only after the bus has been released. The interrupt-driven path has the same flaw from a later commit and is fixed separately, as it carries a different Fixes: tag and stable range. Fixes: 8e8782c71595 ("i2c: imx: add SMBus block read support") Signed-off-by: Vincent Jardin Cc: # v3.16+ Acked-by: Oleksij Rempel Acked-by: Carlos Song Reviewed-by: Stefan Eichenberger Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20260713-for-upstream-i2c-lx2160-fix-v1-v3-1-073ac9e103a5@free.fr diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 28313d0fad37..cfd1e63359e7 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -1415,6 +1415,7 @@ static int i2c_imx_atomic_read(struct imx_i2c_struct *i2c_imx, int i, result; unsigned int temp; int block_data = msgs->flags & I2C_M_RECV_LEN; + int block_err = 0; result = i2c_imx_prepare_read(i2c_imx, msgs, false); if (result) @@ -1436,8 +1437,20 @@ static int i2c_imx_atomic_read(struct imx_i2c_struct *i2c_imx, */ if ((!i) && block_data) { len = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); - if ((len == 0) || (len > I2C_SMBUS_BLOCK_MAX)) - return -EPROTO; + if ((len == 0) || (len > I2C_SMBUS_BLOCK_MAX)) { + /* + * SMBus 3.1 6.5.7: support count byte of 0. + * I2C_SMBUS_BLOCK_MAX case should not hold the SDA either. + */ + if (len > I2C_SMBUS_BLOCK_MAX) + block_err = -EPROTO; + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp |= I2CR_TXAK; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + msgs->buf[0] = 0; + msgs->len = 2; + continue; + } dev_dbg(&i2c_imx->adapter.dev, "<%s> read length: 0x%X\n", __func__, len); @@ -1485,7 +1498,7 @@ static int i2c_imx_atomic_read(struct imx_i2c_struct *i2c_imx, "<%s> read byte: B%d=0x%X\n", __func__, i, msgs->buf[i]); } - return 0; + return block_err; } static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs,