From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1DDAA347517; Wed, 8 Apr 2026 18:10:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775671807; cv=none; b=HElQmPn35Ggd2X10WTObQYRCPzWr8Y4QdRh9nZH2j+TE9x7S9laDFuLLUR6TbVs72vAeJkzCz2Tnh+OP8SE4mYkJv9FkPsMMM6UYnsvE3YtxybShUzMc5K4l4U1H2j7fhxZZ+rqnmJNWs88r8etUYSFxgk8sD97KNpEVttWJKo8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775671807; c=relaxed/simple; bh=Pn+zGy9hJnqQ8OcCoEYaCaPYZonWqJKItHakQgw4F98=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LNKUTOM0gAByI+EgOXwX9tl3uPLv/+gzpbsR5LjyVkljqREkAe/3fr1e3JU9nGN4JX6IAD7oYaq2E3WYjviZKn57JQPQ4fddIwQM5u8fZ5d2Jme+S1dVsniyjHmh7AFOqC11vfUGAIFInY71y0nBEMqaYC9ypPWrN3z1elExPNU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rgbua57Z; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rgbua57Z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA00CC19421; Wed, 8 Apr 2026 18:10:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775671807; bh=Pn+zGy9hJnqQ8OcCoEYaCaPYZonWqJKItHakQgw4F98=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rgbua57ZOwCWe0FBmcc3CLM683QdIdSU5PDyZjm2bfbc5D2Dl+4wnWp5BD/TER3cc tyE3dOzJszx5xRCcyY/rgj5AsR8IvNzZD12UrwT4r/QhkzxtBfH1i0PIx1dNrNT9RG PsS8TVlvD10iyaWb/GXzULNqkvTWnTHsqjrQAzRM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Samasth Norway Ananda , Jani Nikula , Joonas Lahtinen , Sasha Levin Subject: [PATCH 6.1 075/312] drm/i915/gmbus: fix spurious timeout on 512-byte burst reads Date: Wed, 8 Apr 2026 19:59:52 +0200 Message-ID: <20260408175936.543977896@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408175933.715315542@linuxfoundation.org> References: <20260408175933.715315542@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Samasth Norway Ananda [ Upstream commit 08441f10f4dc09fdeb64529953ac308abc79dd38 ] When reading exactly 512 bytes with burst read enabled, the extra_byte_added path breaks out of the inner do-while without decrementing len. The outer while(len) then re-enters and gmbus_wait() times out since all data has been delivered. Decrement len before the break so the outer loop terminates correctly. Fixes: d5dc0f43f268 ("drm/i915/gmbus: Enable burst read") Signed-off-by: Samasth Norway Ananda Reviewed-by: Jani Nikula Link: https://patch.msgid.link/20260316231920.135438-2-samasth.norway.ananda@oracle.com Signed-off-by: Jani Nikula (cherry picked from commit 4ab0f09ee73fc853d00466682635f67c531f909c) Signed-off-by: Joonas Lahtinen Signed-off-by: Sasha Levin --- drivers/gpu/drm/i915/display/intel_gmbus.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/display/intel_gmbus.c b/drivers/gpu/drm/i915/display/intel_gmbus.c index 74443f57f62df..8595f7e7fc34c 100644 --- a/drivers/gpu/drm/i915/display/intel_gmbus.c +++ b/drivers/gpu/drm/i915/display/intel_gmbus.c @@ -470,8 +470,10 @@ gmbus_xfer_read_chunk(struct drm_i915_private *i915, val = intel_de_read_fw(i915, GMBUS3(i915)); do { - if (extra_byte_added && len == 1) + if (extra_byte_added && len == 1) { + len--; break; + } *buf++ = val & 0xff; val >>= 8; -- 2.53.0