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Wed, 15 Jul 2026 00:31:10 -0700 (PDT) X-Received: by 2002:ac8:5d4e:0:b0:51c:1744:edf0 with SMTP id d75a77b69052e-51cbf289286mr135432081cf.9.1784100670440; Wed, 15 Jul 2026 00:31:10 -0700 (PDT) Received: from [192.168.120.193] ([178.235.128.140]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c15fc29937esm790840866b.22.2026.07.15.00.31.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Jul 2026 00:31:09 -0700 (PDT) Message-ID: Date: Wed, 15 Jul 2026 09:31:06 +0200 Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V4] i2c: qcom-geni: Add dynamic transfer timeout based on transfer length and frequency To: Mukesh Savaliya , Aniket Randive , viken.dadhaniya@oss.qualcomm.com, andi.shyti@kernel.org, sumit.semwal@linaro.org, christian.koenig@amd.com Cc: linux-i2c@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, naresh.maramaina@oss.qualcomm.com References: <20260710161056.1799019-1-aniket.randive@oss.qualcomm.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzE1MDA3MSBTYWx0ZWRfX3FTWA4/Jx6Xe WWASbf5dcUdsURC1l2bH8t2mLMS5JfjFZXXxRLT3qjHveISVr8hPBDYgFC/jfh67wCNfbdhZ5ec rZ5LBDrz1C8C1ZEeO5gg5G9dWJBk2GVuTLOo+jP/xSgBmFQHwY/XAyTQqr44hapbnVUTi8qRlMW Grcg3xQyhojncrDCvOGv0R6WYpIC99yefmGc44zt8ho6Kw5/IzLzIzZxwETN4+IlKVfGQ8N8DfR kUQkam2Q/hnyRwVcpKtTOkqIdIA7QbRdym922XnOpZ+cT0ik5zOO9W8kEYpo+FjOozNd1WVURi8 9f+TGcwVS6u0IRwh7OtbOy0YrYsvUC+p/x8owdV/O+d8yZcG74hGHbKSIovY+sWwUNtkEysVn1k oB1YUVgYxqBM7bdpwZFchMDnfzhhKcp8oBY787l8O1uDXL8PTolCG6KlnPq/gblm2Wd0KvTYixq Rvda1bruJZoiFLbUrHA== X-Proofpoint-Spam-Info: AW1haW4tMjYwNzE1MDA3MSBTYWx0ZWRfX9F7q1JhZ3vwx cPTgh9dksD1LnM6BCfwJ5joHJJo2j0LvEjX+F3XfXth1XT1qYMWqP6K5xNWWj/rTcTaVLppoy6g NAAFtNYC1WCGM8A64vWcLe9kc4CAzMY= X-Authority-Analysis: v=2.4 cv=U+Oiy+ru c=1 sm=1 tr=0 ts=6a57373f cx=c_pps a=HLyN3IcIa5EE8TELMZ618Q==:117 a=PRfkaYvzSr8QmIIGAkY2Sg==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_glEPmIy2e8OvE2BGh3C:22 a=EUspDBNiAAAA:8 a=lLXzRi4vikbFFa1iuNgA:9 a=QEXdDO2ut3YA:10 a=bTQJ7kPSJx9SKPbeHEYW:22 X-Proofpoint-GUID: apRYPvDz9SPQe-2g_7gXwMT4zfYkTAPd X-Proofpoint-ORIG-GUID: apRYPvDz9SPQe-2g_7gXwMT4zfYkTAPd 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=2026-07-15_02,2026-07-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 malwarescore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 adultscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607150071 On 7/15/26 6:06 AM, Mukesh Savaliya wrote: > Hi Aniket, Thanks for addressing previous comments. > > On 7/10/2026 9:40 PM, Aniket Randive wrote: >> The driver uses a static XFER_TIMEOUT of HZ (1 second) for all transfers >> regardless of message length or bus frequency, causing unnecessary >> delays on error paths. >> >> Compute the timeout dynamically from message length and bus frequency >> with a 10x safety margin over the theoretical wire time. Add a 300ms >> floor to budget for I2C clock stretching, where a slave may hold SCL >> low indefinitely during internal processing. This detects real hangs > not only internal processing but it may go bad holding SCL low indefinitely. >> 3x faster than the old 1s static timeout. > Meaning, in such case/scenario, don't need to wait till fixes timeout. > I guess, 3x faster is relative to the 1 sec, but for larger data and slower frequency it may not be 3x. Hence, correct it accordingly. >> >> For GPI multi-descriptor transfers, use the maximum message length across >> all queued messages as the per-completion timeout. >> >> Signed-off-by: Aniket Randive >> --- [...] >> +/* 300ms floor: budget for clock stretching; slave may hold SCL low indefinitely */ > Already explained in commit log, can remove second part. This is very much non-obvious, please keep it Konrad