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Mon, 24 Mar 2025 08:29:53 +0000 (GMT) Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA04.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 52O8TrI4004033 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 24 Mar 2025 08:29:53 GMT Received: from [10.231.195.67] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Mon, 24 Mar 2025 01:29:51 -0700 Message-ID: Date: Mon, 24 Mar 2025 16:29:49 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] wifi: ath12k: extend dma mask to 36 bits To: Johan Hovold CC: Johan Hovold , Jeff Johnson , Stephan Gerhold , , References: <20250321162331.19507-1-johan+linaro@kernel.org> Content-Language: en-US From: Baochen Qiang In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Authority-Analysis: v=2.4 cv=BoydwZX5 c=1 sm=1 tr=0 ts=67e11801 cx=c_pps a=ouPCqIW2jiPt+lZRy3xVPw==:117 a=ouPCqIW2jiPt+lZRy3xVPw==:17 a=GEpy-HfZoHoA:10 a=IkcTkHD0fZMA:10 a=Vs1iUdzkB0EA:10 a=UeQ6FwR1gd7q9h-8i14A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: r0qJsfyVh6xZTopEqkXPRjRqzQzd8leJ X-Proofpoint-ORIG-GUID: r0qJsfyVh6xZTopEqkXPRjRqzQzd8leJ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1093,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-24_04,2025-03-21_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 mlxscore=0 spamscore=0 adultscore=0 bulkscore=0 clxscore=1015 malwarescore=0 impostorscore=0 priorityscore=1501 mlxlogscore=760 lowpriorityscore=0 suspectscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2503240061 On 3/24/2025 4:20 PM, Johan Hovold wrote: > On Mon, Mar 24, 2025 at 04:05:33PM +0800, Baochen Qiang wrote: >> On 3/24/2025 3:40 PM, Johan Hovold wrote: >>> On Mon, Mar 24, 2025 at 11:06:16AM +0800, Baochen Qiang wrote: >>>> On 3/22/2025 12:23 AM, Johan Hovold wrote: >>>>> Extend the DMA mask to 36 bits to avoid using bounce buffers on machines >>>>> without an iommu (under OS control) similar to what was done for ath11k >>>>> in commit dbd73acb22d8 ("wifi: ath11k: enable 36 bit mask for stream >>>>> DMA"). >>>>> >>>>> This specifically avoids using bounce buffers on Qualcomm Snapdragon X >>>>> Elite machines like the Lenovo ThinkPad T14s when running at EL1. > >>>>> Note that the mask could possibly be extended further but unresolved DMA >>>>> issues with 64 GiB X Elite machines currently prevents that from being >>>>> tested. >>>> >>>> could you help elaborate how it could be extended? >>> >>> The mask should reflect the capability of the device. That may be >>> 64 (or 40) bits, but I've only been able to test using 36 bits. >> >> are you talking about QCN9274? As far as I know, WCN7850 does not support 40 bits or more. > > Or really all devices handled by ath12k since they at least currently > use a common mask. > > The T14s has a: > > 0004:01:00.0 Network controller: Qualcomm Technologies, Inc WCN785x Wi-Fi 7(802.11be) 320MHz 2x2 [FastConnect 7800] (rev 01) > > ath12k_pci 0004:01:00.0: Hardware name: wcn7850 hw2.0 > ath12k_pci 0004:01:00.0: chip_id 0x2 chip_family 0x4 board_id 0xff soc_id 0x40170200 > > Sounds like 36 bits is the correct choice for now then. yes, let's keep it as 36 for now. > > Johan