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[103.229.18.19]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d022a45f1esm21550055ad.20.2026.07.29.23.40.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 29 Jul 2026 23:40:25 -0700 (PDT) Message-ID: Date: Thu, 30 Jul 2026 12:10:20 +0530 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 6/8] platform: arm64: qcom-hamoa-ec: Retry I2C transfers on NACK To: Konrad Dybcio , Sibi Sankar , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Hans de Goede , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , Bryan O'Donoghue , Bjorn Andersson , Konrad Dybcio Cc: linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org References: <20260728-ec_add_more_commands-v1-0-771abd65ee1a@oss.qualcomm.com> <20260728-ec_add_more_commands-v1-6-771abd65ee1a@oss.qualcomm.com> Content-Language: en-US From: Anvesh Jain P In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMwMDA0NSBTYWx0ZWRfX9H2y/FXO00Dy 8722Iw3h3ofMWmba8iiFNKHD89SBhoOBCLSaxn2Zn9oAggRyFNXrUFiypx3Lfd6dmg+3x6+y08n zFUJ+U3w7k4UwJ0PUeqrJrWVqQbNLs3k8YgbTprlVdVxD84R0aSMArBoY78Bl+XA+zQNvsSYZzm ZE8Yy9uJWbPfnvxzG9r0HETcmZNdvlhGV3cNgmz4eTNBqOKJPmSdYVr0CfHO2D+3jJqTf8SDyYM 664eD0PZbArYLs7xwUDQrFY8o3mqPnfQJZ5NWDpmWhhFu/+S/3EQ9HgVuxegp43/JdBSyN+bTNa vG7Hvabgd+XKCAADRnZPyydFXETTHsFtAkH7mXTYckNMT6iQSMOWOiyA5TLS8SJEOKfxtVA9UiL w3Ijabu1asMP4Xfg51UW+PtG5Dpxj6Gvqdv1fxLXUkVLJb+3CazN9V4PNJzBg//bLre+WY1ScPR WWn88uYYwcFstbLx6Wg== X-Proofpoint-GUID: w6IMVZKYiJ60IGYRtUAzSe9ulprWgqQj X-Authority-Analysis: v=2.4 cv=M6x97Sws c=1 sm=1 tr=0 ts=6a6af1db cx=c_pps a=Oh5Dbbf/trHjhBongsHeRQ==:117 a=Ou0eQOY4+eZoSc0qltEV5Q==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=YMgV9FUhrdKAYTUUvYB2:22 a=EUspDBNiAAAA:8 a=It6PG1r-qJMbqxhxAG0A:9 a=QEXdDO2ut3YA:10 a=_Vgx9l1VpLgwpw_dHYaR:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzMwMDA0NSBTYWx0ZWRfX+3Ue48pa0Ess 1mRPdm5iywW1Qh/DdNtR9e2fkvM2+CTHJ4ZOWyLsICJ/fIlcjJrrmPAy0BcWGwSeaxlvffgINEm CcGvCe+zfSv+a+hfcuHU5LvExWXphWQ= X-Proofpoint-ORIG-GUID: w6IMVZKYiJ60IGYRtUAzSe9ulprWgqQj X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-30_02,2026-07-29_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 suspectscore=0 lowpriorityscore=0 malwarescore=0 priorityscore=1501 impostorscore=0 phishscore=0 clxscore=1015 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607300045 On 7/29/2026 4:41 PM, Konrad Dybcio wrote: > On 7/28/26 7:44 PM, Anvesh Jain P wrote: >> The EC firmware NACKs the bus instead of clock-stretching while it is >> busy servicing internal work (e.g. right after boot, when it is also >> emitting a burst of SCI events). A transfer issued in that window fails >> with -ENXIO even though the EC is otherwise healthy. >> >> This isn't visible with the smbus-only command set used previously; it >> surfaced while stress-testing the new fan LUT command on Hamoa, which >> issues raw i2c_transfer() calls more aggressively and is thus more >> likely to land in the NACK window right after boot or during an SCI >> event burst. >> >> Retry qcom_ec_write() and qcom_ec_read() a bounded number of times with >> a short delay when the EC NACKs the transfer, before giving up. >> >> Signed-off-by: Anvesh Jain P >> --- > [...] > >> enum qcom_ec_sci_events { >> EC_FAN1_STATUS_CHANGE_EVT = 0x30, >> EC_FAN2_STATUS_CHANGE_EVT, >> @@ -233,11 +245,20 @@ static int qcom_ec_write(struct qcom_ec *ec, u8 cmd, const u8 *data, size_t len) >> msg.buf[0] = cmd; >> memcpy(&msg.buf[1], data, len); >> >> - ret = i2c_transfer(ec->client->adapter, &msg, 1); >> + for (int i = 0; i < EC_I2C_NACK_MAX_ATTEMPTS; i++) { >> + ret = i2c_transfer(ec->client->adapter, &msg, 1); >> + ret = ret == 1 ? 0 : (ret < 0 ? ret : -EIO); > Please break this monster up. I know it already exists in-tree, but > since you're moving it around, we might as well. Agreed, will break that up into an explicit if/else instead of the nested ternary in both qcom_ec_write() and qcom_ec_read(). -- Best Regards, Anvesh